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Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
Explore Nov 6, 2011 #178
An intimate look at a newly hatched Atala butterfly! I was a couple of inches away so I can show you details we rarely see. Butterfly wings are not perfect, especially not the Atala's with their blurry edges and random sky blue shapes. Yet let the sunlight catch them in flight, and nothing is more perfect!
Notice the deep orange pigment particles that have fallen from the Atala's body onto its dark blue wings. And the iridescent sky blue patches glistening in the heavy shiny air after this morning's rain.
Early Florida settlers learned from the Indians how to arrowroot flower from the roots of the Coontie plant, the host plant of the Atala. The only plant they lay their eggs on. Arrowroot became the prime money crop and the Coontie plants were destroyed. And the Atala as well, becoming nearly extinct until an upsurge of interest in the Atala led landscapers to begin using it. The Atala population is still small but there's hope for the recovery of both the Coontie and the Atala.
Atala Eumaeus, Chapman's Senna
These Atalas have just hatched! And they will hang till they dry and strengthen, then fly to a nearby nectar source to gain energy and vitality. So rare to see Atalas hatch, and even more rare to see so many hatching at the same time! A lot of us did a lot of work to get Coonties planted and Atala larvae introduced in open fields, along railroad tracks and in landscaping projects.
The Atala butterfly is strange to photograph. The colored areas are vague at the margins so the color looks like it has been dusted on a bit carelessly. But look at its marvelous tones below... deep velvety blue, bright sky blue and a brilliant red orange! It is very fast moving so getting a shot at all is always a thrill! Usually looks like a vibrant patch of astounding flying color and it's gone.
Interdependencies in nature once again. This marvelous creature owes its life to the Florida Coontie which was almost wiped out after being the money crop of the first Florida pioneers. Without the Coontie, this beauty will be gone. Coontie is the host plant and the only plant the Atala can lay its eggs on. The short, woody stem and rootstock of the Coontie grows almost completely underground and produces a terminal crown of stiff, evergreen, pinnate leaves up to 3 feet long. The brown, fleshy, erect, female or seed-bearing cones are pendent when mature. Coontie plants contain a natural toxin, which atala larvae accumulate in their bodies and use to repel birds. Without coontie, adult atalas have no place to lay eggs. No eggs means no new generations. .
Wild coonties’ demise began with starch: Long before Europeans arrived in Florida, Native Americans used coontie as a source of starch. Coontie, in fact, is a Seminole word that means “bread” or “white root” because the roots can be made into arrowroot flour. The Tequesta Indians thrived in the Arch Creek area. The oak hammock near the creek provided shade, edible plants, nuts and berries. Nearby Biscayne Bay provided shellfish, shark, manatee and turtle. North of the hammock were pine flatlands which sheltered the all-important coontie plant (Zamia integrifolia).
Around 1858 two ambitious pioneers used the creek and its natural bridge as a site for a coontie starch mill. These early entrepreneurs learned how to clean the poisonous roots and dammed up the waterway under the bridge diverting the flow through a sluice they carved out of a solid limestone bank. The water turned a wooden wheel attached to a nail-studded grinder which mashed the cootie roots into a paste-like pulp which was soaked and strained to remove any remaining poison. Laid out in wooden racks, the starch dried quickly and the sun bleached it white. In the early 1900s, several commercial factories in South Florida processed coontie roots for the manufacture of arrowroot biscuits. Unfortunately the coontie was overused and the Atala had no place to lay its eggs. In recent years, there is a great effort to reestablish coontie and as a result the Atala is coming back! And coming back abundantlyl!
Atala Eumaeus
Miami, FL
This photo featured in Butterfly Gardening: The North American Butterfly Association Guide. Pg 24 www.amazon.com/Butterfly-Gardening-North-American-Associa...
For more images of this rare, nearly extinct beauty, see my set Florida Butterflies.
Fairchild Tropical Botanic Garden, Miami, FL
For more images of this rare, nearly extinct beauty, see my set Florida Butterflies.
El Voleibol, desde el punto de vista técnico-metodológico, se incluye en los deportes colectivos con pelota. Se caracteriza por realizar sus acciones en condiciones de interrelación e interdependencia. Las acciones se caracterizan por su variabilidad y se hace necesario el dominio de todo un sistema de hábitos motores.
El que logre ganar tres de cinco sets es el vencedor, o también el equipo que gane dos de tres sets. En caso de empate en sets, el último se juega a 15 puntos
"We all live in a globalised, interdependent world. The desire to disengage, to be less constrained by one's partners, to be free to do things entirely as one chooses, is entirely understandable. And yet in reality for many countries, disengaging and turning inwards will likely lead to less security, less prosperity, and a dimmer future."
Lee Hsien Loong, Prime Minister of Singapore
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
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Ecosystem?
We live in ecosystems - Cultural, Financial and Environmental…they’re all related and interdependent. Actually, everything is dependent on our Environmental Ecosystem, because without food, water and air there is no human culture or opportunity to do business and support the human world we’ve created. Caring Currency will fill the gaps and connect the dots, making our lives meaningful.
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Lamellae, Singapore
Ahtehha, 2019
A shelf and display case for research (printed/3d pritned) in the Digital Manufacturing and Design lab.
A multi-agent approach to fabrication. Adapting a lamella system assembly to freeform geometry, every element has a reciprocal relationship with the neighboring pieces creating a complex, interdependent geometry. This is heightened by using 5-axis CNC swarf cutting to maintain surface continuity at joints and integrating all mortise and tenon connections. Each element is modelled as an instance of an agent that determines positioning, relationships with adjacent members, and geometric requirements. The precision of the geometry and CNC fabrication allows for direct assembly that holds by friction-fit alone.
Jennifer Campbell’s work describes instinctual aspects of humanity correlating to, and differing from, societal structuring. A recent B.F.A. graduate of Watkins College of Art, Design & Film, she currently works and resides in Nashville. Her photographic series, “System of Interdependent Terms,” has recently been exhibited in the Sylvia White Gallery in Ventura, California, as well as the Chromatics Gallery, and the Brownlee O. Currey Jr. gallery in Nashville, Tennessee.
See: www.jrac-art.com/gallery/index.html
[Oil on canvas, 91.5 X 152.5 cm]
gandalfsgalleymodern.blogspot.com/2011/10/jennifer-campbe...
Kālī, also known as Kālikā (Sanskrit: कालिका), is the Hindu goddess associated with empowerment, shakti. She is the fierce aspect of the goddess Durga (Parvati). The name Kali comes from kāla, which means black, time, death, lord of death: Shiva. Since Shiva is called Kāla— the eternal time — the name of Kālī, his consort, also means "Time" or "Death" (as in "time has come"). Hence, Kāli is the Goddess of Time and Change. Although sometimes presented as dark and violent, her earliest incarnation as a figure of annihilation of evil forces still has some influence. Various Shakta Hindu cosmologies, as well as Shākta Tantric beliefs, worship her as the ultimate reality or Brahman. Comparatively recent devotional movements largely conceive Kāli as a benevolent mother goddess. Kālī is represented as the consort of Lord Shiva, on whose body she is often seen standing. Shiva lies in the path of Kali, whose foot on Shiva subdues her anger.
ETYMOLOGY
Kālī is the feminine form of kālam ("black, dark coloured"). Kāla primarily means "time" but also means "black" in honor of being the first creation before light itself. Kālī means "the black one" and refers to her being the entity of "time" or "beyond time." Kāli is strongly associated with Shiva, and Shaivas derive the masculine Kāla (an epithet of Shiva) to come from her feminine name. A nineteenth-century Sanskrit dictionary, the Shabdakalpadrum, states: कालः शिवः। तस्य पत्नीति - काली। kālaḥ śivaḥ। tasya patnīti kālī - "Shiva is Kāla, thus, his consort is Kāli" referring to Devi Parvathi being a manifestation of Devi MahaKali.
Other names include Kālarātri ("black night"), as described above, and Kālikā ("relating to time"). Coburn notes that the name Kālī can be used as a proper name, or as a description of color.
Kāli's association with darkness stands in contrast to her consort, Shiva, who manifested after her in creation, and who symbolises the rest of creation after Time is created. In his supreme awareness of Maya, his body is covered by the white ashes of the cremation ground (Sanskrit: śmaśāna) where he meditates, and with which Kāli is also associated, as śmaśāna-kālī.
ORIGINS
Hugh Urban notes that although the word Kālī appears as early as the Atharva Veda, the first use of it as a proper name is in the Kathaka Grhya Sutra (19.7). Kali is the name of one of the seven tongues of Agni, the [Rigvedic] God of Fire, in the Mundaka Upanishad (2:4), but it is unlikely that this refers to the goddess. The first appearance of Kāli in her present form is in the Sauptika Parvan of the Mahabharata (10.8.64). She is called Kālarātri (literally, "black night") and appears to the Pandava soldiers in dreams, until finally she appears amidst the fighting during an attack by Drona's son Ashwatthama. She most famously appears in the sixth century Devi Mahatmyam as one of the shaktis of Mahadevi, and defeats the demon Raktabija ("Bloodseed"). The tenth-century Kalika Purana venerates Kāli as the ultimate reality.
According to David Kinsley, Kāli is first mentioned in Hinduism as a distinct goddess around 600 CE, and these texts "usually place her on the periphery of Hindu society or on the battlefield." She is often regarded as the Shakti of Shiva, and is closely associated with him in various Puranas. The Kalika Purana depicts her as the "Adi Shakti" (Fundamental Power) and "Para Prakriti" or beyond nature.
WORSHIP & MANTRA
Kali could be considered a general concept, like Durga, and is mostly worshiped in the Kali Kula sect of worship. The closest way of direct worship is Maha Kali or Bhadra Kali (Bhadra in Sanskrit means 'gentle'). Kali is worshiped as one of the 10 Mahavidya forms of Adi Parashakti (Goddess Durga) or Bhagavathy according to the region. The mantra for worship is called Devi Argala Stotram.
Sanskrit: सर्वमङ्गलमाङ्गल्ये शिवे सर्वार्थसाधिके । शरण्ये त्र्यम्बके गौरि नारायणि नमोऽस्तु ते ॥
ॐ जयंती मंगल काली भद्रकाली कपालिनी । दुर्गा क्षमा शिवा धात्री स्वाहा स्वधा नमोऽस्तुते ॥
(Sarvamaṅgalamāṅgalyē śivē sarvārthasādhikē . śaraṇyē tryambakē gauri nārāyaṇi namō'stu tē.
Oṃ jayantī mangala kālī bhadrakālī kapālinī . durgā kṣamā śivā dhātrī svāhā svadhā namō'stutē.)
TANTRA
Goddesses play an important role in the study and practice of Tantra Yoga, and are affirmed to be as central to discerning the nature of reality as are the male deities. Although Parvati is often said to be the recipient and student of Shiva's wisdom in the form of Tantras, it is Kāli who seems to dominate much of the Tantric iconography, texts, and rituals. In many sources Kāli is praised as the highest reality or greatest of all deities. The Nirvana-tantra says the gods Brahma, Vishnu, and Shiva all arise from her like bubbles in the sea, ceaselessly arising and passing away, leaving their original source unchanged. The Niruttara-tantra and the Picchila-tantra declare all of Kāli's mantras to be the greatest and the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra all proclaim Kāli vidyas (manifestations of Mahadevi, or "divinity itself"). They declare her to be an essence of her own form (svarupa) of the Mahadevi.
In the Mahanirvana-tantra, Kāli is one of the epithets for the primordial sakti, and in one passage Shiva praises her:
At the dissolution of things, it is Kāla [Time] Who will devour all, and by reason of this He is called Mahākāla [an epithet of Lord Shiva], and since Thou devourest Mahākāla Himself, it is Thou who art the Supreme Primordial Kālika. Because Thou devourest Kāla, Thou art Kāli, the original form of all things, and because Thou art the Origin of and devourest all things Thou art called the Adya [the Primordial One]. Re-assuming after Dissolution Thine own form, dark and formless, Thou alone remainest as One ineffable and inconceivable. Though having a form, yet art Thou formless; though Thyself without beginning, multiform by the power of Maya, Thou art the Beginning of all, Creatrix, Protectress, and Destructress that Thou art.
The figure of Kāli conveys death, destruction, and the consuming aspects of reality. As such, she is also a "forbidden thing", or even death itself. In the Pancatattva ritual, the sadhaka boldly seeks to confront Kali, and thereby assimilates and transforms her into a vehicle of salvation. This is clear in the work of the Karpuradi-stotra, a short praise of Kāli describing the Pancatattva ritual unto her, performed on cremation grounds. (Samahana-sadhana)
He, O Mahākāli who in the cremation-ground, naked, and with dishevelled hair, intently meditates upon Thee and recites Thy mantra, and with each recitation makes offering to Thee of a thousand Akanda flowers with seed, becomes without any effort a Lord of the earth. Oh Kāli, whoever on Tuesday at midnight, having uttered Thy mantra, makes offering even but once with devotion to Thee of a hair of his Shakti [his energy/female companion] in the cremation-ground, becomes a great poet, a Lord of the earth, and ever goes mounted upon an elephant.
The Karpuradi-stotra clearly indicates that Kāli is more than a terrible, vicious, slayer of demons who serves Durga or Shiva. Here, she is identified as the supreme mistress of the universe, associated with the five elements. In union with Lord Shiva, she creates and destroys worlds. Her appearance also takes a different turn, befitting her role as ruler of the world and object of meditation. In contrast to her terrible aspects, she takes on hints of a more benign dimension. She is described as young and beautiful, has a gentle smile, and makes gestures with her two right hands to dispel any fear and offer boons. The more positive features exposed offer the distillation of divine wrath into a goddess of salvation, who rids the sadhaka of fear. Here, Kali appears as a symbol of triumph over death.
BENGALI TRADITION
Kali is also a central figure in late medieval Bengali devotional literature, with such devotees as Ramprasad Sen (1718–75). With the exception of being associated with Parvati as Shiva's consort, Kāli is rarely pictured in Hindu legends and iconography as a motherly figure until Bengali devotions beginning in the early eighteenth century. Even in Bengāli tradition her appearance and habits change little, if at all.
The Tantric approach to Kāli is to display courage by confronting her on cremation grounds in the dead of night, despite her terrible appearance. In contrast, the Bengali devotee appropriates Kāli's teachings adopting the attitude of a child, coming to love her unreservedly. In both cases, the goal of the devotee is to become reconciled with death and to learn acceptance of the way that things are. These themes are well addressed in Rāmprasād's work. Rāmprasād comments in many of his other songs that Kāli is indifferent to his wellbeing, causes him to suffer, brings his worldly desires to nothing and his worldly goods to ruin. He also states that she does not behave like a mother should and that she ignores his pleas:
Can mercy be found in the heart of her who was born of the stone? [a reference to Kali as the daughter of Himalaya]
Were she not merciless, would she kick the breast of her lord?
Men call you merciful, but there is no trace of mercy in you, Mother.
You have cut off the heads of the children of others, and these you wear as a garland around your neck.
It matters not how much I call you "Mother, Mother." You hear me, but you will not listen.
To be a child of Kāli, Rāmprasād asserts, is to be denied of earthly delights and pleasures. Kāli is said to refrain from giving that which is expected. To the devotee, it is perhaps her very refusal to do so that enables her devotees to reflect on dimensions of themselves and of reality that go beyond the material world.
A significant portion of Bengali devotional music features Kāli as its central theme and is known as Shyama Sangeet ("Music of the Night"). Mostly sung by male vocalists, today even women have taken to this form of music. One of the finest singers of Shyāma Sāngeet is Pannalal Bhattacharya.
In Bengal, Kāli is venerated in the festival Kali Puja, the new moon day of Ashwin month which coincides with Diwali festival.
In a unique form of Kāli worship, Shantipur worships Kāli in the form of a hand painted image of the deity known as Poteshwari (meaning the deity drawn on a piece of cloth).
LEGENDS
SLAYER OF RAKTABIJA
In Kāli's most famous legend, Devi Durga (Adi Parashakti) and her assistants, the Matrikas, wound the demon Raktabija, in various ways and with a variety of weapons in an attempt to destroy him. They soon find that they have worsened the situation for with every drop of blood that is dripped from Raktabija he reproduces a clone of himself. The battlefield becomes increasingly filled with his duplicates. Durga, in need of help, summons Kāli to combat the demons. It is said, in some versions, that Goddess Durga actually assumes the form of Goddess Kāli at this time. The Devi Mahatmyam describes:
Out of the surface of her (Durga's) forehead, fierce with frown, issued suddenly Kali of terrible countenance, armed with a sword and noose. Bearing the strange khatvanga (skull-topped staff ), decorated with a garland of skulls, clad in a tiger's skin, very appalling owing to her emaciated flesh, with gaping mouth, fearful with her tongue lolling out, having deep reddish eyes, filling the regions of the sky with her roars, falling upon impetuously and slaughtering the great asuras in that army, she devoured those hordes of the foes of the devas.
Kali destroys Raktabija by sucking the blood from his body and putting the many Raktabija duplicates in her gaping mouth. Pleased with her victory, Kali then dances on the field of battle, stepping on the corpses of the slain. In the Devi Mahatmya version of this story, Kali is also described as a Matrika and as a Shakti or power of Devi. She is given the epithet Cāṃuṇḍā (Chamunda), i.e. the slayer of the demons Chanda and Munda. Chamunda is very often identified with Kali and is very much like her in appearance and habit.
DAKSHINA KALI
In her most famous pose as Daksinakali, popular legends say that Kali, becoming drunk on the blood of her victims on the battlefield, dances with destructive frenzy. She is about to destroy the whole universe when, urged by all the gods, Shiva lies in her way to stop her. In her fury, she fails to see the body of Shiva lying amongst the corpses on the battlefield and steps upon his chest. Realizing Shiva lies beneath her feet, her anger is pacified and she calms her fury. Though not included in any of the puranas, popular legends state that Kali was ashamed at the prospect of keeping her husband beneath her feet and thus stuck her tongue out in shame. The Devi-Bhagavata Purana, which goes into great depths about the goddess Kali, reveals the tongue's actual symbolism.
The characteristic icons that depict Kali are the following; unbridled matted hair, open blood shot eyes, open mouth and a drooping tongue; in her hands, she holds a Khadga (bent sword or scimitar) and a human head; she has a girdle of human hands across her waist and an enchanted Shiva lies beneath her feet. Each of these icons represent a deep philosophical epithet. The drooping out-stuck tongue represents her blood-thirst. Lord Shiva beneath her feet represents matter, as Kali is undoubtedly the primeval energy. The depiction of Kali on Shiva shows that without energy, matter lies "dead". This concept has been simplified to a folk-tale depicting a wife placing her foot on her husband and sticking her tongue out in shame. In tantric contexts, the tongue is seen to denote the element (guna) of rajas (energy and action) controlled by sattva.
If Kali steps on Shiva with her right foot and holds the sword in her left hand, she is considered to be Dakshina Kali. The Dakshina Kali Temple has important religious associations with the Jagannath Temple and it is believed that Daksinakali is the guardian of the kitchen of the Lord Jagannath Temple. Puranic tradition says that in Puri, Lord Jagannath is regarded as Daksinakalika. Goddess Dakshinakali plays an important role in the 'Niti' of Saptapuri Amavasya.
One South Indian tradition tells of a dance contest between Shiva and Kali. After defeating the two demons Sumbha and Nisumbha, Kali takes up residence in the forest of Thiruvalankadu or Thiruvalangadu. She terrorizes the surrounding area with her fierce, disruptive nature. One of Shiva's devotees becomes distracted while performing austerities, and asks Shiva to rid the forest of the destructive goddess. When Shiva arrives, Kali threatens him, claiming the territory as her own. Shiva challenges Kali to a dance contest; both of them dance and Kali matches Shiva in every step that he takes until Shiva takes the "Urdhvatandava" step, by vertically raising his right leg. Kali refuses to perform this step, which would not befit her as a woman, and became pacified.
SMASHAN KALI
If the Kali steps out with the left foot and holds the sword in her right hand, she is the terrible form of Mother, the Smashan Kali of the cremation ground. She is worshiped by tantrics, the followers of Tantra, who believe that one's spiritual discipline practiced in a smashan (cremation ground) brings success quickly. Sarda Devi, the consort of Ramakrishna Paramhansa, worshipped Smashan Kali at Dakshineshwar.
MATERNAL KALI
Another legend depicts the infant Shiva calming Kali. In this similar story, Kali has defeated her enemies on the battlefield and begun to dance out of control, drunk on the blood of the slain. To calm her down and to protect the stability of the world, Shiva is sent to the battlefield, as an infant, crying aloud. Seeing the child's distress, Kali ceases dancing to care for the helpless infant. She picks him up, kisses his head, and proceeds to breast feed the infant Shiva. This legend is notable because it shows Kali in her benevolent, maternal aspect, with which she is not usually identified.
MAHAKALI
Mahakali (Sanskrit: Mahākālī, Devanagari: महाकाली), literally translated as Great Kali, is sometimes considered as a greater form of Kali, identified with the Ultimate reality of Brahman. It can also be used as an honorific of the Goddess Kali, signifying her greatness by the prefix "Mahā-". Mahakali, in Sanskrit, is etymologically the feminized variant of Mahakala or Great Time (which is interpreted also as Death), an epithet of the God Shiva in Hinduism. Mahakali is the presiding Goddess of the first episode of the Devi Mahatmya. Here she is depicted as Devi in her universal form as Shakti. Here Devi serves as the agent who allows the cosmic order to be restored.
Kali is depicted in the Mahakali form as having ten heads, ten arms, and ten legs. Each of her ten hands is carrying a various implement which vary in different accounts, but each of these represent the power of one of the Devas or Hindu Gods and are often the identifying weapon or ritual item of a given Deva. The implication is that Mahakali subsumes and is responsible for the powers that these deities possess and this is in line with the interpretation that Mahakali is identical with Brahman. While not displaying ten heads, an "ekamukhi" or one headed image may be displayed with ten arms, signifying the same concept: the powers of the various Gods come only through Her grace.
ICONOGRAPHY
Kali is portrayed mostly in two forms: the popular four-armed form and the ten-armed Mahakali form. In both of her forms, she is described as being black in color but is most often depicted as blue in popular Indian art. Her eyes are described as red with intoxication, and in absolute rage, her hair is shown disheveled, small fangs sometimes protrude out of her mouth, and her tongue is lolling. She is often shown naked or just wearing a skirt made of human arms and a garland of human heads. She is also accompanied by serpents and a jackal while standing on a seemingly dead Shiva, usually right foot forward to symbolize the more popular Dakshinamarga or right-handed path, as opposed to the more infamous and transgressive Vamamarga or left-handed path.
In the ten-armed form of Mahakali she is depicted as shining like a blue stone. She has ten faces and ten feet and three eyes. She has ornaments decked on all her limbs. There is no association with Shiva.
The Kalika Purana describes Kali as possessing a soothing dark complexion, as perfectly beautiful, riding a lion, four-armed, holding a sword and blue lotuses, her hair unrestrained, body firm and youthful.
In spite of her seemingly terrible form, Kali Ma is often considered the kindest and most loving of all the Hindu goddesses, as she is regarded by her devotees as the Mother of the whole Universe. And because of her terrible form, she is also often seen as a great protector. When the Bengali saint Ramakrishna once asked a devotee why one would prefer to worship Mother over him, this devotee rhetorically replied, "Maharaj, when they are in trouble your devotees come running to you. But, where do you run when you are in trouble?"
According to Ramakrishna, darkness is the Ultimate Mother, or Kali:
My Mother is the principle of consciousness. She is Akhanda Satchidananda; indivisible Reality, Awareness, and Bliss. The night sky between the stars is perfectly black. The waters of the ocean depths are the same; The infinite is always mysteriously dark. This inebriating darkness is my beloved Kali.
SRI RAMAKRISHNA
This is clear in the works of such contemporary artists as Charles Wish, and Tyeb Mehta, who sometimes take great liberties with the traditional, accepted symbolism, but still demonstrate a true reverence for the Shakta sect.
POPULAR FORM
Classic depictions of Kali share several features, as follows:
Kali's most common four armed iconographic image shows each hand carrying variously a sword, a trishul (trident), a severed head and a bowl or skull-cup (kapala) catching the blood of the severed head.
Two of these hands (usually the left) are holding a sword and a severed head. The Sword signifies Divine Knowledge and the Human Head signifies human Ego which must be slain by Divine Knowledge in order to attain Moksha. The other two hands (usually the right) are in the abhaya (fearlessness) and varada (blessing) mudras, which means her initiated devotees (or anyone worshipping her with a true heart) will be saved as she will guide them here and in the hereafter.
She has a garland consisting of human heads, variously enumerated at 108 (an auspicious number in Hinduism and the number of countable beads on a Japa Mala or rosary for repetition of Mantras) or 51, which represents Varnamala or the Garland of letters of the Sanskrit alphabet, Devanagari. Hindus believe Sanskrit is a language of dynamism, and each of these letters represents a form of energy, or a form of Kali. Therefore she is generally seen as the mother of language, and all mantras.
She is often depicted naked which symbolizes her being beyond the covering of Maya since she is pure (nirguna) being-consciousness-bliss and far above prakriti. She is shown as very dark as she is brahman in its supreme unmanifest state. She has no permanent qualities - she will continue to exist even when the universe ends. It is therefore believed that the concepts of color, light, good, bad do not apply to her - she is the pure, un-manifested energy, the Adi-shakti.
SHIVA IN KALI ICONOGRAPHY
In both these images she is shown standing on the prone, inert or dead body of Shiva. There is a legend for the reason behind her standing on what appears to be Shiva's corpse, which translates as follows:
Once Kali had destroyed all the demons in battle, she began a terrific dance out of the sheer joy of victory. All the worlds or lokas began to tremble and sway under the impact of her dance. So, at the request of all the Gods, Shiva himself asked her to desist from this behavior. However, she was too intoxicated to listen. Hence, Shiva lay like a corpse among the slain demons in order to absorb the shock of the dance into himself. When Kali eventually stepped upon Shiva, she realized she was trampling and hurting her husband and bit her tongue in shame.
The story described here is a popular folk tale and not described or hinted in any of the puranas. The puranic interpretation is as follows:
Once, Parvati asks Shiva to chose the one form among her 10 forms which he likes most. To her surprise, Shiva reveals that he is most comfortable with her Kali form, in which she is bereft of her jewellery, her human-form, her clothes, her emotions and where she is only raw, chaotic energy, where she is as terrible as time itself and even greater than time. As Parvati takes the form of Kali, Shiva lies at her feet and requests her to place her foot on his chest, upon his heart. Once in this form, Shiva requests her to have this place, below her feet in her iconic image which would be worshiped throughout.
This idea has been explored in the Devi-Bhagavata Purana and is most popular in the Shyama Sangeet, devotional songs to Kali from the 12th to 15th centuries.
The Tantric interpretation of Kali standing on top of her husband is as follows:
The Shiv tattava (Divine Consciousness as Shiva) is inactive, while the Shakti tattava (Divine Energy as Kali) is active. Shiva and Kali represent Brahman, the Absolute pure consciousness which is beyond all names, forms and activities. Kali, on the other hand, represents the potential (and manifested) energy responsible for all names, forms and activities. She is his Shakti, or creative power, and is seen as the substance behind the entire content of all consciousness. She can never exist apart from Shiva or act independently of him, just as Shiva remains a mere corpse without Kali i.e., Shakti, all the matter/energy of the universe, is not distinct from Shiva, or Brahman, but is rather the dynamic power of Brahman. Hence, Kali is Para Brahman in the feminine and dynamic aspect while Shiva is the male aspect and static. She stands as the absolute basis for all life, energy and beneath her feet lies, Shiva, a metaphor for mass, which cannot retain its form without energy.
While this is an advanced concept in monistic Shaktism, it also agrees with the Nondual Trika philosophy of Kashmir, popularly known as Kashmir Shaivism and associated most famously with Abhinavagupta. There is a colloquial saying that "Shiva without Shakti is Shava" which means that without the power of action (Shakti) that is Mahakali (represented as the short "i" in Devanagari) Shiva (or consciousness itself) is inactive; Shava means corpse in Sanskrit and the play on words is that all Sanskrit consonants are assumed to be followed by a short letter "a" unless otherwise noted. The short letter "i" represents the female power or Shakti that activates Creation. This is often the explanation for why She is standing on Shiva, who is either Her husband and complement in Shaktism or the Supreme Godhead in Shaivism.
To properly understand this complex Tantric symbolism it is important to remember that the meaning behind Shiva and Kali does not stray from the non-dualistic parlance of Shankara or the Upanisads. According to both the Mahanirvana and Kularnava Tantras, there are two distinct ways of perceiving the same absolute reality. The first is a transcendental plane which is often described as static, yet infinite. It is here that there is no matter, there is no universe and only consciousness exists. This form of reality is known as Shiva, the absolute Sat-Chit-Ananda - existence, knowledge and bliss. The second is an active plane, an immanent plane, the plane of matter, of Maya, i.e., where the illusion of space-time and the appearance of an actual universe does exist. This form of reality is known as Kali or Shakti, and (in its entirety) is still specified as the same Absolute Sat-Chit-Ananda. It is here in this second plane that the universe (as we commonly know it) is experienced and is described by the Tantric seer as the play of Shakti, or God as Mother Kali.
From a Tantric perspective, when one meditates on reality at rest, as absolute pure consciousness (without the activities of creation, preservation or dissolution) one refers to this as Shiva or Brahman. When one meditates on reality as dynamic and creative, as the Absolute content of pure consciousness (with all the activities of creation, preservation or dissolution) one refers to it as Kali or Shakti. However, in either case the yogini or yogi is interested in one and the same reality - the only difference being in name and fluctuating aspects of appearance. It is this which is generally accepted as the meaning of Kali standing on the chest of Shiva.
Although there is often controversy surrounding the images of divine copulation, the general consensus is benign and free from any carnal impurities in its substance. In Tantra the human body is a symbol for the microcosm of the universe; therefore sexual process is responsible for the creation of the world. Although theoretically Shiva and Kali (or Shakti) are inseparable, like fire and its power to burn, in the case of creation they are often seen as having separate roles. With Shiva as male and Kali as female it is only by their union that creation may transpire. This reminds us of the prakrti and purusa doctrine of Samkhya wherein prakāśa- vimarśa has no practical value, just as without prakrti, purusa is quite inactive. This (once again) stresses the interdependencies of Shiva and Shakti and the vitality of their union.
Gopi Krishna proposed that Kali standing on the dead Shiva or Shava (Sanskrit for dead body) symbolised the helplessness of a person undergoing the changing process (psychologically and physiologically) in the body conducted by the Kundalini Shakti.
DEVELOPMENT
In the later traditions, Kali has become inextricably linked with Shiva. The unleashed form of Kali often becomes wild and uncontrollable, and only Shiva is able to tame her just as only Kali can tame Shiva. This is both because she is often a transformed version of one of his consorts and because he is able to match her wildness.
The ancient text of Kali Kautuvam describes her competition with Shiva in dance, from which the sacred 108 Karanas appeared. Shiva won the competition by acting the urdva tandava, one of the Karanas, by raising his feet to his head. Other texts describe Shiva appearing as a crying infant and appealing to her maternal instincts. While Shiva is said to be able to tame her, the iconography often presents her dancing on his fallen body, and there are accounts of the two of them dancing together, and driving each other to such wildness that the world comes close to unravelling.
Shiva's involvement with Tantra and Kali's dark nature have led to her becoming an important Tantric figure. To the Tantric worshippers, it was essential to face her Curse, the terror of death, as willingly as they accepted Blessings from her beautiful, nurturing, maternal aspect. For them, wisdom meant learning that no coin has only one side: as death cannot exist without life, so life cannot exist without death. Kali's role sometimes grew beyond that of a chaos - which could be confronted - to that of one who could bring wisdom, and she is given great metaphysical significance by some Tantric texts. The Nirvāna-tantra clearly presents her uncontrolled nature as the Ultimate Reality, claiming that the trimurti of Brahma, Vishnu and Rudra arise and disappear from her like bubbles from the sea. Although this is an extreme case, the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra declare her the svarupa (own-being) of the Mahadevi (the great Goddess, who is in this case seen as the combination of all devis).
The final stage of development is the worshipping of Kali as the Great Mother, devoid of her usual violence. This practice is a break from the more traditional depictions. The pioneers of this tradition are the 18th century Shakta poets such as Ramprasad Sen, who show an awareness of Kali's ambivalent nature. Ramakrishna, the 19th century Bengali saint, was also a great devotee of Kali; the western popularity of whom may have contributed to the more modern, equivocal interpretations of this Goddess. Rachel McDermott's work, however, suggests that for the common, modern worshipper, Kali is not seen as fearful, and only those educated in old traditions see her as having a wrathful component. Some credit to the development of Devi must also be given to Samkhya. Commonly referred to as the Devi of delusion, Mahamaya or Durga, acting in the confines of (but not being bound by) the nature of the three gunas, takes three forms: Maha-Kali, Maha-Lakshmi and Maha-Saraswati, being her tamas-ika, rajas-ika and sattva-ika forms. In this sense, Kali is simply part of a larger whole.
Like Sir John Woodroffe and Georg Feuerstein, many Tantric scholars (as well as sincere practitioners) agree that, no matter how propitious or appalling you describe them, Shiva and Devi are simply recognizable symbols for everyday, abstract (yet tangible) concepts such as perception, knowledge, space-time, causation and the process of liberating oneself from the confines of such things. Shiva, symbolizing pure, absolute consciousness, and Devi, symbolizing the entire content of that consciousness, are ultimately one and the same - totality incarnate, a micro-macro-cosmic amalgamation of all subjects, all objects and all phenomenal relations between the "two." Like man and woman who both share many common, human traits yet at the same time they are still different and, therefore, may also be seen as complementary.
Worshippers prescribe various benign and horrific qualities to Devi simply out of practicality. They do this so they may have a variety of symbols to choose from, symbols which they can identify and relate with from the perspective of their own, ever-changing time, place and personal level of unfolding. Just like modern chemists or physicists use a variety of molecular and atomic models to describe what is unperceivable through rudimentary, sensory input, the scientists of ontology and epistemology must do the same. One of the underlying distinctions of Tantra, in comparison to other religions, is that it allows the devotee the liberty to choose from a vast array of complementary symbols and rhetoric which suit one's evolving needs and tastes. From an aesthetic standpoint, nothing is interdict and nothing is orthodox. In this sense, the projection of some of Devi's more gentle qualities onto Kali is not sacrilege and the development of Kali really lies in the practitioner, not the murthi.
A TIME magazine article of October 27, 1947, used Kali as a symbol and metaphor for the human suffering in British India during its partition that year.
Swami Vivekananda wrote his favorite poem Kali the Mother in 1898.
IN NEW AGE & NEOPAGANISM
An academic study of Western Kali enthusiasts noted that, "as shown in the histories of all cross-cultural religious transplants, Kali devotionalism in the West must take on its own indigenous forms if it is to adapt to its new environment." The adoption of Kali by the West has raised accusations of cultural appropriation:
A variety of writers and thinkers have found Kali an exciting figure for reflection and exploration, notably feminists and participants in New Age spirituality who are attracted to goddess worship. Kali is a symbol of wholeness and healing, associated especially with repressed female power and sexuality. [However, such interpretations often exhibit] confusion and misrepresentation, stemming from a lack of knowledge of Hindu history among these authors, draw upon materials written by scholars of the Hindu religious tradition. The majority instead rely chiefly on other popular feminist sources, almost none of which base their interpretations on a close reading of Kali's Indian background. The most important issue arising from this discussion - even more important than the question of 'correct' interpretation - concerns the adoption of other people's religious symbols. It is hard to import the worship of a goddess from another culture: religious associations and connotations have to be learned, imagined or intuited when the deep symbolic meanings embedded in the native culture are not available.
WIKIPEDIA
Random thoughts:
The breeze knows better
How to teach a child
The skills of breathing and expanding
Become a child through love and air
And forgive the force of the uknown
Всеки човек е различен и не може всички да сме еднакви: The snail is slow and steady and appreciates the path that he is on...not solely focused on where he is going.
***
This implies that the art of life is more like navigation than warfare, for what is important is to understand the winds, the tides, the currents, the seasons, and the principles of growth and decay, so that one’s actions may use them and not fight them:
creativesystemsthinking.wordpress.com/2015/07/31/the-taoi...
***
Because they are mutually arising, figure and ground exist interdependently, in dynamic relation to each other: “We are not aware of any figure — be it an image, sound, or tactile impression — except in relation to a background. . . . What we perceive is never a figure alone but a figure/ground relationship” (Watts, 1974, p. 19). Thus the nature of perception is to apprehend not just the figure, but the entire field or the figure-ground relationship. The relationship between the figure and the ground is the meaning. When we fight this natural process of perceiving the figure-ground relationships, we lose the creative tension that builds meaning in our lives. As Jung has said, “Meaninglessness inhibits fullness of life and is therefore equivalent to illness. Meaning makes a great many things endurable-perhaps everything” (1963, p. 340).In Gestalt therapy, this interplay between the figure and ground is critical to the health and viability of the self, on maintaining the elasticity of the figure/ground relationship, and it is, in the Gestalt view, the process of growth and maturation.
www.yourheroicjourney.com/hsiang-sheng-polarity-in-the-he...
My Art
My Art is no art
Without my mind's simplicity.
My Art does not want
To subscribe to the view
That unhappiness
Commands the world.
When I paint or draw,
I keep my mind's thought-garden
Completely free of self-doubt-weeds.
My Art is the hide-and-seek
Between my soul's illumining smiles
And my heart's streaming tears.
The Artist in me has three
Faithful, sleepless
And self-giving friends:
A newness-eye, a oneness-heart
And a fulness-life.
The heart of my Art
And the heart of a child
Are extremely fond of each other.
They love each other deeply;
They need each other constantly;
They are interdependent, sleeplessly.
My mind says that anything I do
Is too insignificant
Because I am wanting
In qualification.
Needless to say,
This includes my Artwork.
My heart says that anything I do
Is too significant
Because the God-Touch
Is always there.
Needless to say,
This includes my Artwork.
The moment I start painting,
I clearly see my soul-meditation
Is blessingfully clasping
My heart-aspiration-flames.
First things first:
The Artist in me,
Before embarking on his Artwork,
Invariably catches
His heart's aspiration-express.
True, in my Art I want to see
The face of earth's beauty.
But I want to see
The heart of Heaven's Divinity
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The Dakshinkali Temple is located 22 kilometers from Kathmandu next to the village of Pharping. It's one of the main temples in Nepal. Twice every week thousands of people come here to worship the goddess Kali by sacrificing life animals, particularly cockerels and uncastrated male goats.
GODDESS KALI
Kālī (/ˈkɑːli/; Sanskrit: काली & Bengali: কালী; IPA: [kɑːliː]), also known as Kālikā (Sanskrit: कालिका), is the Hindu goddess associated with empowerment, or shakti. She is the fierce aspect of the goddess Durga. The name of Kali means black one and force of time; she is therefore called the Goddess of Time, Change, Power, Creation, Preservation, and Destruction. Her earliest appearance is that of a destroyer principally of evil forces. Various Shakta Hindu cosmologies, as well as Shākta Tantric beliefs, worship her as the ultimate reality or Brahman; and recent devotional movements re-imagine Kāli as a benevolent mother goddess. She is often portrayed standing or dancing on her husband, the god Shiva, who lies calm and prostrate beneath her. Worshipped throughout India but particularly South India, Bengal, and Assam, Kali is both geographically and culturally marginal.
ETYMOLOGY
Kālī is the feminine form of kālam ("black, dark coloured"). Kāla primarily means "time", but also means "black"; hence, Kālī means "the black one" or "beyond time". Kāli is strongly associated with Shiva, and Shaivas derive the masculine Kāla (an epithet of Shiva) from her feminine name. A nineteenth-century Sanskrit dictionary, the Shabdakalpadrum, states: कालः शिवः। तस्य पत्नीति - काली। kālaḥ śivaḥ। tasya patnīti kālī - "Shiva is Kāla, thus, his consort is Kāli".
Other names include Kālarātri ("black night"), as described above, and Kālikā ("relating to time"), and Kallie ("black alchemist"). Coburn notes that the name Kālī can be used as a proper name, or as a description of color.
Kāli's association with darkness stands in contrast to her consort, Shiva, whose body is covered by the white ashes of the cremation ground (Sanskrit: śmaśāna) where he meditates, and with which Kāli is also associated, as śmaśāna-kālī.
ORIGINS
Hugh Urban notes that although the word Kālī appears as early as the Atharva Veda, the first use of it as a proper name is in the Kathaka Grhya Sutra (19.7). Kali is the name of one of the seven tongues of Agni, the [Rigvedic] God of Fire, in the Mundaka Upanishad (2:4), but it is unlikely that this refers to the goddess. The first appearance of Kāli in her present form is in the Sauptika Parvan of the Mahabharata (10.8.64). She is called Kālarātri (literally, "black night") and appears to the Pandava soldiers in dreams, until finally she appears amidst the fighting during an attack by Drona's son Ashwatthama. She most famously appears in the sixth century Devi Mahatmyam as one of the shaktis of Mahadevi, and defeats the demon Raktabija ("Bloodseed"). The tenth-century Kalika Purana venerates Kāli as the ultimate reality.
According to David Kinsley, Kāli is first mentioned in Hinduism as a distinct goddess around 600 CE, and these texts "usually place her on the periphery of Hindu society or on the battlefield." She is often regarded as the Shakti of Shiva, and is closely associated with him in various Puranas. The Kalika Purana depicts her as the "Adi Shakti" (Fundamental Power) and "Para Prakriti" or beyond nature.
WORSHIP AND MANTRA
Kali could be considered a general concept, like Durga, and is mostly worshiped in the Kali Kula sect of worship. The closest way of direct worship is Maha Kali or Bhadra Kali (Bhadra in Sanskrit means 'gentle'). Kali is worshiped as one of the 10 Mahavidya forms of Adi Parashakti (Goddess Durga) or Bhagavathy according to the region. The mantra for worship is
Sanskrit: सर्वमङ्गलमाङ्गल्ये शिवे सर्वार्थसाधिके । शरण्ये त्र्यम्बके गौरि नारायणि नमोऽस्तु ते ॥
ॐ जयंती मंगल काली भद्रकाली कपालिनी । दुर्गा शिवा क्षमा धात्री स्वाहा स्वधा नमोऽस्तुते ॥
(Sarvamaṅgalamāṅgalyē śivē sarvārthasādhikē . śaraṇyē tryambakē gauri nārāyaṇi namō'stu tē.
Oṃ jayantī mangala kālī bhadrakālī kapālinī . durgā śivā ksamā dhātrī svāhā svadhā namō'stutē.)
YANTRA
Goddesses play an important role in the study and practice of Tantra Yoga, and are affirmed to be as central to discerning the nature of reality as are the male deities. Although Parvati is often said to be the recipient and student of Shiva's wisdom in the form of Tantras, it is Kali who seems to dominate much of the Tantric iconography, texts, and rituals. In many sources Kāli is praised as the highest reality or greatest of all deities. The Nirvana-tantra says the gods Brahma, Vishnu, and Shiva all arise from her like bubbles in the sea, ceaselessly arising and passing away, leaving their original source unchanged. The Niruttara-tantra and the Picchila-tantra declare all of Kāli's mantras to be the greatest and the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra all proclaim Kāli vidyas (manifestations of Mahadevi, or "divinity itself"). They declare her to be an essence of her own form (svarupa) of the Mahadevi.In the Mahanirvana-tantra, Kāli is one of the epithets for the primordial sakti, and in one passage Shiva praises her:At the dissolution of things, it is Kāla [Time]. Who will devour all, and by reason of this He is called Mahākāla [an epithet of Lord Shiva], and since Thou devourest Mahākāla Himself, it is Thou who art the Supreme Primordial Kālika. Because Thou devourest Kāla, Thou art Kāli, the original form of all things, and because Thou art the Origin of and devourest all things Thou art called the Adya [the Primordial One]. Re-assuming after Dissolution Thine own form, dark and formless, Thou alone remainest as One ineffable and inconceivable. Though having a form, yet art Thou formless; though Thyself without beginning, multiform by the power of Maya, Thou art the Beginning of all, Creatrix, Protectress, and Destructress that Thou art. The figure of Kāli conveys death, destruction, and the consuming aspects of reality. As such, she is also a "forbidden thing", or even death itself. In the Pancatattva ritual, the sadhaka boldly seeks to confront Kali, and thereby assimilates and transforms her into a vehicle of salvation. This is clear in the work of the Karpuradi-stotra, a short praise of Kāli describing the Pancatattva ritual unto her, performed on cremation grounds. (Samahana-sadhana)He, O Mahākāli who in the cremation-ground, naked, and with dishevelled hair, intently meditates upon Thee and recites Thy mantra, and with each recitation makes offering to Thee of a thousand Akanda flowers with seed, becomes without any effort a Lord of the earth. Oh Kāli, whoever on Tuesday at midnight, having uttered Thy mantra, makes offering even but once with devotion to Thee of a hair of his Shakti [his energy/female companion] in the cremation-ground, becomes a great poet, a Lord of the earth, and ever goes mounted upon an elephant.The Karpuradi-stotra clearly indicates that Kāli is more than a terrible, vicious, slayer of demons who serves Durga or Shiva. Here, she is identified as the supreme mistress of the universe, associated with the five elements. In union with Lord Shiva, she creates and destroys worlds. Her appearance also takes a different turn, befitting her role as ruler of the world and object of meditation. In contrast to her terrible aspects, she takes on hints of a more benign dimension. She is described as young and beautiful, has a gentle smile, and makes gestures with her two right hands to dispel any fear and offer boons. The more positive features exposed offer the distillation of divine wrath into a goddess of salvation, who rids the sadhaka of fear. Here, Kali appears as a symbol of triumph over death.
BENGALI TRADITION
Kali is also a central figure in late medieval Bengali devotional literature, with such devotees as Ramprasad Sen (1718–75). With the exception of being associated with Parvati as Shiva's consort, Kāli is rarely pictured in Hindu legends and iconography as a motherly figure until Bengali devotions beginning in the early eighteenth century. Even in Bengāli tradition her appearance and habits change little, if at all.
The Tantric approach to Kāli is to display courage by confronting her on cremation grounds in the dead of night, despite her terrible appearance. In contrast, the Bengali devotee appropriates Kāli's teachings adopting the attitude of a child, coming to love her unreservedly. In both cases, the goal of the devotee is to become reconciled with death and to learn acceptance of the way that things are. These themes are well addressed in Rāmprasād's work. Rāmprasād comments in many of his other songs that Kāli is indifferent to his wellbeing, causes him to suffer, brings his worldly desires to nothing and his worldly goods to ruin. He also states that she does not behave like a mother should and that she ignores his pleas:
Can mercy be found in the heart of her who was born of the stone? [a reference to Kali as the daughter of Himalaya]
Were she not merciless, would she kick the breast of her lord?
Men call you merciful, but there is no trace of mercy in you, Mother.
You have cut off the heads of the children of others, and these you wear as a garland around your neck.
It matters not how much I call you "Mother, Mother." You hear me, but you will not listen.
To be a child of Kāli, Rāmprasād asserts, is to be denied of earthly delights and pleasures. Kāli is said to refrain from giving that which is expected. To the devotee, it is perhaps her very refusal to do so that enables her devotees to reflect on dimensions of themselves and of reality that go beyond the material world.
A significant portion of Bengali devotional music features Kāli as its central theme and is known as Shyama Sangeet ("Music of the Night"). Mostly sung by male vocalists, today even women have taken to this form of music. One of the finest singers of Shyāma Sāngeet is Pannalal Bhattacharya.
In Bengal, Kāli is venerated in the festival Kali Puja, the new moon day of Ashwin month which coincides with Diwali festival.
In a unique form of Kāli worship, Shantipur worships Kāli in the form of a hand painted image of the deity known as Poteshwari (meaning the deity drawn on a piece of cloth).
LEGENDS
SLAYER AND RAKTABIJA
In Kāli's most famous legend, Devi Durga (Adi Parashakti) and her assistants, the Matrikas, wound the demon Raktabija, in various ways and with a variety of weapons in an attempt to destroy him. They soon find that they have worsened the situation for with every drop of blood that is dripped from Raktabija he reproduces a clone of himself. The battlefield becomes increasingly filled with his duplicates. Durga, in need of help, summons Kāli to combat the demons. It is said, in some versions, that Goddess Durga actually assumes the form of Goddess Kāli at this time. The Devi Mahatmyam describes:
Out of the surface of her (Durga's) forehead, fierce with frown, issued suddenly Kali of terrible countenance, armed with a sword and noose. Bearing the strange khatvanga (skull-topped staff ), decorated with a garland of skulls, clad in a tiger's skin, very appalling owing to her emaciated flesh, with gaping mouth, fearful with her tongue lolling out, having deep reddish eyes, filling the regions of the sky with her roars, falling upon impetuously and slaughtering the great asuras in that army, she devoured those hordes of the foes of the devas.
Kali consumes Raktabija and his duplicates, and dances on the corpses of the slain. In the Devi Mahatmya version of this story, Kali is also described as a Matrika and as a Shakti or power of Devi. She is given the epithet Cāṃuṇḍā (Chamunda), i.e. the slayer of the demons Chanda and Munda. Chamunda is very often identified with Kali and is very much like her in appearance and habit.
DAKSHINA KALI
In her most famous pose as Daksinakali, popular legends say that Kali, drunk on the blood of her victims, is about to destroy the whole universe when, urged by all the gods, Shiva lies in her way to stop her, and she steps upon his chest. Recognizing Shiva beneath her feet, she calms herself. Though not included in any of the puranas, popular legends state that Kali was ashamed at the prospect of keeping her husband beneath her feet and thus stuck her tongue out in shame. The Devi-Bhagavata Purana, which goes into great depths about the goddess Kali, reveals the tongue's actual symbolism.
The characteristic icons that depict Kali are the following; unbridled matted hair, open blood shot eyes, open mouth and a drooping tongue; in her hands, she holds a Khadga (bent sword or scimitar) and a human head; she has a girdle of human hands across her waist, and Shiva lies beneath her feet. The drooping out-stuck tongue represents her blood-thirst. Lord Shiva beneath her feet represents matter, as Kali energy. The depiction of Kali on Shiva shows that without energy, matter lies "dead". This concept has been simplified to a folk-tale depicting a wife placing her foot
on her husband and sticking her tongue out in shame. In tantric contexts, the tongue is seen to denote the element (guna) of rajas (energy and action) controlled by sattva.
If Kali steps on Shiva with her right foot and holds the sword in her left hand, she is considered to be Dakshina Kali. The Dakshina Kali Temple has important religious associations with the Jagannath Temple and it is believed that Daksinakali is the guardian of the kitchen of the Lord Jagannath Temple. Puranic tradition says that in Puri, Lord Jagannath is regarded as Daksinakalika. Goddess Dakshinakali plays an important role in the 'Niti' of Saptapuri Amavasya.
One South Indian tradition tells of a dance contest between Shiva and Kali. After defeating the two demons Sumbha and Nisumbha, Kali takes up residence in the forest of Thiruvalankadu or Thiruvalangadu. She terrorizes the surrounding area with her fierce, disruptive nature. One of Shiva's devotees becomes distracted while performing austerities, and asks Shiva to rid the forest of the destructive goddess. When Shiva arrives, Kali threatens him, and Shiva challenges Kali to a dance contest, wherein Kali matches Shiva until Shiva takes the "Urdhvatandava" step, vertically raising his right leg. Kali refuses to perform this step, which would not befit her as a woman, and becomes pacified.
SMASHAN KALI
If the Kali steps out with the left foot and holds the sword in her right hand, she is the terrible form of Mother, the Smashan Kali of the cremation ground. She is worshiped by tantrics, the followers of Tantra, who believe that one's spiritual discipline practiced in a smashan (cremation ground) brings success quickly. Sarda Devi, the consort of Ramakrishna Paramhansa, worshipped Smashan Kali at Dakshineshwar.
MATERNAL KALI
At the time of samundra manthan when amrit came out, along with that came out poison which was going to destroy the world hence on the request of all the gods, Lord Shiva drank it to save the world but as he is beyond death he didn't die but was very much in pain due to the poison effect hence he became a child so that Kali can feed him with her milk which will sooth out the poison effect.
MAHAKALI
Mahakali (Sanskrit: Mahākālī, Devanagari: महाकाली), literally translated as Great Kali, is sometimes considered as a greater form of Kali, identified with the Ultimate reality of Brahman. It can also be used as an honorific of the Goddess Kali, signifying her greatness by the prefix "Mahā-". Mahakali, in Sanskrit, is etymologically the feminized variant of Mahakala or Great Time (which is interpreted also as Death), an epithet of the God Shiva in Hinduism. Mahakali is the presiding Goddess of the first episode of the Devi Mahatmya. Here she is depicted as Devi in her universal form as Shakti. Here Devi serves as the agent who allows the cosmic order to be restored.
Kali is depicted in the Mahakali form as having ten heads, ten arms, and ten legs. Each of her ten hands is carrying a various implement which vary in different accounts, but each of these represent the power of one of the Devas or Hindu Gods and are often the identifying weapon or ritual item of a given Deva. The implication is that Mahakali subsumes and is responsible for the powers that these deities possess and this is in line with the interpretation that Mahakali is identical with Brahman. While not displaying ten heads, an "ekamukhi" or one headed image may be displayed with ten arms, signifying the same concept: the powers of the various Gods come only through Her grace.
ICONOGRAPHY
Kali is portrayed mostly in two forms: the popular four-armed form and the ten-armed Mahakali form. In both of her forms, she is described as being black in color but is most often depicted as blue in popular Indian art. Her eyes are described as red with intoxication, and in absolute rage, her hair is shown disheveled, small fangs sometimes protrude out of her mouth, and her tongue is lolling. She is often shown naked or just wearing a skirt made of human arms and a garland of human heads. She is also accompanied by serpents and a jackal while standing on a seemingly dead Shiva, usually right foot forward to symbolize the more popular Dakshinamarga or right-handed path, as opposed to the more infamous and transgressive Vamamarga or left-handed path.
In the ten-armed form of Mahakali she is depicted as shining like a blue stone. She has ten faces, ten feet, and three eyes for each head. She has ornaments decked on all her limbs. There is no association with Shiva.
The Kalika Purana describes Kali as possessing a soothing dark complexion, as perfectly beautiful, riding a lion, four-armed, holding a sword and blue lotuses, her hair unrestrained, body firm and youthful.
In spite of her seemingly terrible form, Kali Ma is often considered the kindest and most loving of all the Hindu goddesses, as she is regarded by her devotees as the Mother of the whole Universe. And because of her terrible form, she is also often seen as a great protector. When the Bengali saint Ramakrishna once asked a devotee why one would prefer to worship Mother over him, this devotee rhetorically replied, "Maharaj", when they are in trouble your devotees come running to you. But, where do you run when you are in trouble?"
According to Ramakrishna, darkness is the Ultimate Mother, or Kali:
My Mother is the principle of consciousness. She is Akhanda Satchidananda;
indivisible Reality, Awareness, and Bliss. The night sky between the stars is perfectly black.
The waters of the ocean depths are the same; The infinite is always mysteriously dark.
This inebriating darkness is my beloved Kali.
—Sri Ramakrishna
This is clear in the works of such contemporary artists as Charles Wish, and Tyeb Mehta, who sometimes take great liberties with the traditional, accepted symbolism, but still demonstrate a true reverence for the Shakta sect.
POPULAR FORM
Classic depictions of Kali share several features, as follows:
Kali's most common four armed iconographic image shows each hand carrying variously a sword, a trishul (trident), a severed head, and a bowl or skull-cup (kapala) catching the blood of the severed head.
Two of these hands (usually the left) are holding a sword and a severed head. The Sword signifies Divine Knowledge and the Human Head signifies human Ego which must be slain by Divine Knowledge in order to attain Moksha. The other two hands (usually the right) are in the abhaya (fearlessness) and varada (blessing) mudras, which means her initiated devotees (or anyone worshipping her with a true heart) will be saved as she will guide them here and in the hereafter.
She has a garland consisting of human heads, variously enumerated at 108 (an auspicious number in Hinduism and the number of countable beads on a Japa Mala or rosary for repetition of Mantras) or 51, which represents Varnamala or the Garland of letters of the Sanskrit alphabet, Devanagari. Hindus believe Sanskrit is a language of dynamism, and each of these letters represents a form of energy, or a form of Kali. Therefore, she is generally seen as the mother of language, and all mantras.
She is often depicted naked which symbolizes her being beyond the covering of Maya since she is pure (nirguna) being-consciousness-bliss and far above prakriti. She is shown as very dark as she is brahman in its supreme unmanifest state. She has no permanent qualities - she will continue to exist even when the universe ends. It is therefore believed that the concepts of color, light, good, bad do not apply to her - she is the pure, un-manifested energy, the Adi-shakti.
Kali as the Symbol of Creation , Freedom , Preservation and Destruction
The head that hangs in Kali's hand is a symbol of Ego and the scimitar which she is holding represents power and energy.It is believed that Kali is protecting the human race by that scimitar and also destroying the negativity and ego within human being. The body lying under Kali symbolizes ruination, is actually a form of Shiva. Kali steps her leg on the chest of the body and suppress ruination . Since she is standing on the pure white chest of Lord Shiva who, as pure primal awareness, lays in a passive reclining position, peacefully lies with his eyes half open in a state of bliss. Her hair is long, black and flowing freely depicting Her freedom from convention and the confines of conceptualization. The white teeth which Kali has stands for conscience and her red tongue represents greed. By pressing her white teeth on her tongue Kali refers to control greed.The goddess may appear terrible from outside but every symbol in Kali signifies truth of life. Since the earth was created out of darkness, the dark black color of Kali symbolizes the color from which everything was born. Her right hand side arms she shows the Abhaya mudra(gesture of fearlessness) and Vara mudra (gesture of welcome and charity) respectively . But on the other arm in left side she holds a bloody scimitar and a severed head depicting destruction and end of ego.
Kali as the Symbol of Mother Nature
The name Kali means Kala or force of time. When there were neither the creation, nor the sun, the moon, the planets, and the earth, there was only darkness and everything was created from the darkness. The Dark appearance of kali represents the darkness from which everything was born. Her complexion is deep blue, like the sky and ocean water as blue. As she is also the goddess of Preservation Kali is worshiped as mother to preserve the nature.Kali is standing calm on Shiva, her appearance represents the preservation of mother nature. Her free, long and black hair represents nature's freedom from civilization. Under the third eye of kali, the signs of both sun, moon and fire are visible which represent the driving forces of nature.
SHIVA IN KALI ICONOGRAPHY
In both these images she is shown standing on the prone, inert or dead body of Shiva. There is a legend for the reason behind her standing on what appears to be Shiva's corpse, which translates as follows:
Once Kali had destroyed all the demons in battle, she began a terrific dance out of the sheer joy of victory. All the worlds or lokas began to tremble and sway under the impact of her dance. So, at the request of all the Gods, Shiva himself asked her to desist from this behavior. However, she was too intoxicated to listen. Hence, Shiva lay like a corpse among the slain demons in order to absorb the shock of the dance into himself. When Kali eventually stepped upon Shiva, she realized she was trampling and hurting her husband and bit her tongue in shame.
The story described here is a popular folk tale and not described or hinted in any of the puranas. The puranic interpretation is as follows:
Once, Parvati asks Shiva to chose the one form among her 10 forms which he likes most. To her surprise, Shiva reveals that he is most comfortable with her Kali form, in which she is bereft of her jewellery, her human-form, her clothes, her emotions and where she is only raw, chaotic energy, where she is as terrible as time itself and even greater than time. As Parvati takes the form of Kali, Shiva lies at her feet and requests her to place her foot on his chest, upon his heart. Once in this form, Shiva requests her to have this place, below her feet in her iconic image which would be worshiped throughout.
This idea has been explored in the Devi-Bhagavata Purana [28] and is most popular in the Shyama Sangeet, devotional songs to Kali from the 12th to 15th centuries.
The Tantric interpretation of Kali standing on top of her husband is as follows:
The Shiv tattava (Divine Consciousness as Shiva) is inactive, while the Shakti tattava (Divine Energy as Kali) is active. Shiva and Kali represent Brahman, the Absolute pure consciousness which is beyond all names, forms and activities. Kali, on the other hand, represents the potential (and manifested) energy responsible for all names, forms and activities. She is his Shakti, or creative power, and is seen as the substance behind the entire content of all consciousness. She can never exist apart from Shiva or act independently of him, just as Shiva remains a mere corpse without Kali i.e., Shakti, all the matter/energy of the universe, is not distinct from Shiva, or Brahman, but is rather the dynamic power of Brahman. Hence, Kali is Para Brahman in the feminine and dynamic aspect while Shiva is the male aspect and static. She stands as the absolute basis for all life, energy and beneath her feet lies, Shiva, a metaphor for mass, which cannot retain its form without energy.
While this is an advanced concept in monistic Shaktism, it also agrees with the Nondual Trika philosophy of Kashmir, popularly known as Kashmir Shaivism and associated most famously with Abhinavagupta. There is a colloquial saying that "Shiva without Shakti is Shava" which means that without the power of action (Shakti) that is Mahakali (represented as the short "i" in Devanagari) Shiva (or consciousness itself) is inactive; Shava means corpse in Sanskrit and the play on words is that all Sanskrit consonants are assumed to be followed by a short letter "a" unless otherwise noted. The short letter "i" represents the female power or Shakti that activates Creation. This is often the explanation for why She is standing on Shiva, who is either Her husband and complement in Shaktism or the Supreme Godhead in Shaivism.
To properly understand this complex Tantric symbolism it is important to remember that the meaning behind Shiva and Kali does not stray from the non-dualistic parlance of Shankara or the Upanisads. According to both the Mahanirvana and Kularnava Tantras, there are two distinct ways of perceiving the same absolute reality. The first is a transcendental plane which is often described as static, yet infinite. It is here that there is no matter, there is no universe and only consciousness exists. This form of reality is known as Shiva, the absolute Sat-Chit-Ananda - existence, knowledge and bliss. The second is an active plane, an immanent plane, the plane of matter, of Maya, i.e., where the illusion of space-time and the appearance of an actual universe does exist. This form of reality is known as Kali or Shakti, and (in its entirety) is still specified as the same Absolute Sat-Chit-Ananda. It is here in this second plane that the universe (as we commonly know it) is experienced and is described by the Tantric seer as the play of Shakti, or God as Mother Kali.
From a Tantric perspective, when one meditates on reality at rest, as absolute pure consciousness (without the activities of creation, preservation or dissolution) one refers to this as Shiva or Brahman. When one meditates on reality as dynamic and creative, as the Absolute content of pure consciousness (with all the activities of creation, preservation or dissolution) one refers to it as Kali or Shakti. However, in either case the yogini or yogi is interested in one and the same reality - the only difference being in name and fluctuating aspects of appearance. It is this which is generally accepted as the meaning of Kali standing on the chest of Shiva.
Although there is often controversy surrounding the images of divine copulation, the general consensus is benign and free from any carnal impurities in its substance. In Tantra the human body is a symbol for the microcosm of the universe; therefore sexual process is responsible for the creation of the world. Although theoretically Shiva and Kali (or Shakti) are inseparable, like fire and its power to burn, in the case of creation they are often seen as having separate roles. With Shiva as male and Kali as female it is only by their union that creation may transpire. This reminds us of the prakrti and purusa doctrine of Samkhya wherein prakāśa- vimarśa has no practical value, just as without prakrti, purusa is quite inactive. This (once again) stresses the interdependencies of Shiva and Shakti and the vitality of their union.
Gopi Krishna proposed that Kali standing on the dead Shiva or Shava (Sanskrit for dead body) symbolised the helplessness of a person undergoing the changing process (psychologically and physiologically) in the body conducted by the Kundalini Shakti.
DEVELOPMENT
In the later traditions, Kali has become inextricably linked with Shiva. The unleashed form of Kali often becomes wild and uncontrollable, and only Shiva is able to tame her just as only Kali can tame Shiva. This is both because she is often a transformed version of one of his consorts and because he is able to match her wildness.
The ancient text of Kali Kautuvam describes her competition with Shiva in dance, from which the sacred 108 Karanas appeared. Shiva won the competition by acting the urdva tandava, one of the Karanas, by raising his feet to his head. Other texts describe Shiva appearing as a crying infant and appealing to her maternal instincts. While Shiva is said to be able to tame her, the iconography often presents her dancing on his fallen body, and there are accounts of the two of them dancing together, and driving each other to such wildness that the world comes close to unravelling.
Shiva's involvement with Tantra and Kali's dark nature have led to her becoming an important Tantric figure. To the Tantric worshippers, it was essential to face her Curse, the terror of death, as willingly as they accepted Blessings from her beautiful, nurturing, maternal aspect. For them, wisdom meant learning that no coin has only one side: as death cannot exist without life, so life cannot exist without death. Kali's role sometimes grew beyond that of a chaos - which could be confronted - to that of one who could bring wisdom, and she is given great metaphysical significance by some Tantric texts. The Nirvāna-tantra clearly presents her uncontrolled nature as the Ultimate Reality, claiming that the trimurti of Brahma, Vishnu and Rudra arise and disappear from her like bubbles from the sea. Although this is an extreme case, the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra declare her the svarupa (own-being) of the Mahadevi (the great Goddess, who is in this case seen as the combination of all devis).The final stage of development is the worshipping of Kali as the Great Mother, devoid of her usual violence. This practice is a break from the more traditional depictions. The pioneers of this tradition are the 18th century Shakta poets such as Ramprasad Sen, who show an awareness of Kali's ambivalent nature. Ramakrishna, the 19th century Bengali saint, was also a great devotee of Kali; the western popularity of whom may have contributed to the more modern, equivocal interpretations of this Goddess. Rachel McDermott's work, however, suggests that for the common, modern worshipper, Kali is not seen as fearful, and only those educated in old traditions see her as having a wrathful component. Some credit to the development of Devi must also be given to Samkhya. Commonly referred to as the Devi of delusion, Mahamaya or Durga, acting in the confines of (but not being bound by) the nature of the three gunas, takes three forms: Maha-Kali, Maha-Lakshmi and Maha-Saraswati, being her tamas-ika, rajas-ika and sattva-ika forms. In this sense, Kali is simply part of a larger whole.
Like Sir John Woodroffe and Georg Feuerstein, many Tantric scholars (as well as sincere practitioners) agree that, no matter how propitious or appalling you describe them, Shiva and Devi are simply recognizable symbols for everyday, abstract (yet tangible) concepts such as perception, knowledge, space-time, causation and the process of liberating oneself from the confines of such things. Shiva, symbolizing pure, absolute consciousness, and Devi, symbolizing the entire content of that consciousness, are ultimately one and the same - totality incarnate, a micro-macro-cosmic amalgamation of all subjects, all objects and all phenomenal relations between the "two." Like man and woman who both share many common, human traits yet at the same time they are still different and, therefore, may also be seen as complementary.
Worshippers prescribe various benign and horrific qualities to Devi simply out of practicality. They do this so they may have a variety of symbols to choose from, symbols which they can identify and relate with from the perspective of their own, ever-changing time, place and personal level of unfolding. Just like modern chemists or physicists use a variety of molecular and atomic models to describe what is unperceivable through rudimentary, sensory input, the scientists of ontology and epistemology must do the same. One of the underlying distinctions of Tantra, in comparison to other religions, is that it allows the devotee the liberty to choose from a vast array of complementary symbols and rhetoric which suit one's evolving needs and tastes. From an aesthetic standpoint, nothing is interdict and nothing is orthodox. In this sense, the projection of some of Devi's more gentle qualities onto Kali is not sacrilege and the development of Kali really lies in the practitioner, not the murthi.
A TIME magazine article of October 27, 1947, used Kali as a symbol and metaphor for the human suffering in British India during its partition that year. In 1971, Ms. Magazine used an image of Kali, her multiple arms juggling modern tasks, as a symbol of modern womanhood on its inaugural issue.
Swami Vivekananda wrote his favorite poem Kali the Mother in 1898.
KALI IN NEOPAGAN AND NEW AGE PRACTICE
An academic study of Western Kali enthusiasts noted that, "as shown in the histories of all cross-cultural religious transplants, Kali devotionalism in the West must take on its own indigenous forms if it is to adapt to its new environment."[60] The adoption of Kali by the West has raised accusations of cultural appropriation:
A variety of writers and thinkers have found Kali an exciting figure for reflection and exploration, notably feminists and participants in New Age spirituality who are attracted to goddess worship. [For them], Kali is a symbol of wholeness and healing, associated especially with repressed female power and sexuality. [However, such interpretations often exhibit] confusion and misrepresentation, stemming from a lack of knowledge of Hindu history among these authors, [who only rarely] draw upon materials written by scholars of the Hindu religious tradition. The majority instead rely chiefly on other popular feminist sources, almost none of which base their interpretations on a close reading of Kali's Indian background. The most important issue arising from this discussion - even more important than the question of 'correct' interpretation - concerns the adoption of other people's religious symbols. It is hard to import the worship of a goddess from another culture: religious associations and connotations have to be learned, imagined or intuited when the deep symbolic meanings embedded in the native culture are not available.
INCARNATIONS OF KALI
Draupadi, Wife of Pandavas, was an avatar of Kali, who born to assist Lord Krishna to destroy arrogant kings of India. There is a temple dedicated to this incarnation at Banni Mata Temple at Himachal Pradesh. The vedic deity Nirriti or the Puranic deity Alakshmi is often considered as incarnations of Kali.
WIKIPEDIA
Hres triptych published in
. Y Sin Embargo Magazine 22 - cap it all/off
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Outlining a Theory of General Creativity . .
. . on a 'Pataphysical projectory
Entropy ≥ Memory ● Creativity ²
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La mecanosfera extrae y actualiza configuraciones que existen entre una infinidad de ellas en los campos de la virtualidad. Las máquinas existenciales están al mismo nivel que el ser en su multiplicidad intrínseca. (...) Son para sí mismas su propio material de expresión semiótica. La existencia, como proceso de desterritorialización, es una operación inter-maquínica específica que se superpone a la promoción de intensidades existenciales singularizadas. (...) La existencia no es dialéctica, no es representable. ¡Apenas es vivible!
(...) Las máquinas del deseo, las máquinas de la creación estética, en tanto máquinas científicas modifican constantemente nuestras fronteras cósmicas. Como tales, ocupan un lugar eminente dentro de los ensamblajes de subjetivación, ellas mismas llamadas a relevar a nuestras antiguas máquinas sociales que son incapaces de seguir la floración de revoluciones maquinarias que sacuden nuestra época desde todas partes. Más que adoptar una actitud reticente con respecto a la inmensa revolución maquinaria que arrasa el planeta (a riesgo de destruirlo) o agarrarse a sistemas de valores tradicionales, fingiendo reestablecer la trascendencia, el movimiento del progreso, o si se prefiere, el movimiento del proceso, se esforzará por reconciliar los valores con las máquinas.
(...) Los sistemas maquínicos se posicionan a sí mismos en un rizoma de interdependencia, situando cada estasis maquínica real en la conjunción de una filiación pasada y un Phylum de futuras mutaciones. Todos los sistemas de valores - religiosos, estéticos, científicos, ecosóficos...- se instalan en esta interfaz maquínica entre lo actual necesario y lo virtual posibilista. (...) De ahí un doble enunciado: finito, territorializado e incorpóreo, infinito.
(...) A la estéril oposición entre valor de uso y valor de intercambio es preciso oponer una complexión axiológica que incluya todas las modalidades maquínicas de valoración: los valores del deseo, los valores estéticos, los valores ecológicos, los valores económicos, etc. (...) La ley económica, como la ley jurídica, debe ser deducida del conjunto de Universos del valor, por cuyo colapso lucha constantemente. Su reconstrucción, sobre los escombros desperdigados de las economías planificadas y el neoliberalismo y según nuevas finalidades etico-políticas (ecosofía), requiere, en contraste, una inagotable renovación de la consistencia de los ensamblajes maquínicos de valoración.
( Félix Guattari - Caosmosis - 1992 )
( traducción por Alicia Pallas )
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rectO-persO | E ≥ m.C² | co~errAnce | TiLt
The Dakshinkali Temple is located 22 kilometers from Kathmandu next to the village of Pharping. It's one of the main temples in Nepal. Twice every week thousands of people come here to worship the goddess Kali by sacrificing life animals, particularly cockerels and uncastrated male goats.
GODDESS KALI
Kālī (/ˈkɑːli/; Sanskrit: काली & Bengali: কালী; IPA: [kɑːliː]), also known as Kālikā (Sanskrit: कालिका), is the Hindu goddess associated with empowerment, or shakti. She is the fierce aspect of the goddess Durga. The name of Kali means black one and force of time; she is therefore called the Goddess of Time, Change, Power, Creation, Preservation, and Destruction. Her earliest appearance is that of a destroyer principally of evil forces. Various Shakta Hindu cosmologies, as well as Shākta Tantric beliefs, worship her as the ultimate reality or Brahman; and recent devotional movements re-imagine Kāli as a benevolent mother goddess. She is often portrayed standing or dancing on her husband, the god Shiva, who lies calm and prostrate beneath her. Worshipped throughout India but particularly South India, Bengal, and Assam, Kali is both geographically and culturally marginal.
ETYMOLOGY
Kālī is the feminine form of kālam ("black, dark coloured"). Kāla primarily means "time", but also means "black"; hence, Kālī means "the black one" or "beyond time". Kāli is strongly associated with Shiva, and Shaivas derive the masculine Kāla (an epithet of Shiva) from her feminine name. A nineteenth-century Sanskrit dictionary, the Shabdakalpadrum, states: कालः शिवः। तस्य पत्नीति - काली। kālaḥ śivaḥ। tasya patnīti kālī - "Shiva is Kāla, thus, his consort is Kāli".
Other names include Kālarātri ("black night"), as described above, and Kālikā ("relating to time"), and Kallie ("black alchemist"). Coburn notes that the name Kālī can be used as a proper name, or as a description of color.
Kāli's association with darkness stands in contrast to her consort, Shiva, whose body is covered by the white ashes of the cremation ground (Sanskrit: śmaśāna) where he meditates, and with which Kāli is also associated, as śmaśāna-kālī.
ORIGINS
Hugh Urban notes that although the word Kālī appears as early as the Atharva Veda, the first use of it as a proper name is in the Kathaka Grhya Sutra (19.7). Kali is the name of one of the seven tongues of Agni, the [Rigvedic] God of Fire, in the Mundaka Upanishad (2:4), but it is unlikely that this refers to the goddess. The first appearance of Kāli in her present form is in the Sauptika Parvan of the Mahabharata (10.8.64). She is called Kālarātri (literally, "black night") and appears to the Pandava soldiers in dreams, until finally she appears amidst the fighting during an attack by Drona's son Ashwatthama. She most famously appears in the sixth century Devi Mahatmyam as one of the shaktis of Mahadevi, and defeats the demon Raktabija ("Bloodseed"). The tenth-century Kalika Purana venerates Kāli as the ultimate reality.
According to David Kinsley, Kāli is first mentioned in Hinduism as a distinct goddess around 600 CE, and these texts "usually place her on the periphery of Hindu society or on the battlefield." She is often regarded as the Shakti of Shiva, and is closely associated with him in various Puranas. The Kalika Purana depicts her as the "Adi Shakti" (Fundamental Power) and "Para Prakriti" or beyond nature.
WORSHIP AND MANTRA
Kali could be considered a general concept, like Durga, and is mostly worshiped in the Kali Kula sect of worship. The closest way of direct worship is Maha Kali or Bhadra Kali (Bhadra in Sanskrit means 'gentle'). Kali is worshiped as one of the 10 Mahavidya forms of Adi Parashakti (Goddess Durga) or Bhagavathy according to the region. The mantra for worship is
Sanskrit: सर्वमङ्गलमाङ्गल्ये शिवे सर्वार्थसाधिके । शरण्ये त्र्यम्बके गौरि नारायणि नमोऽस्तु ते ॥
ॐ जयंती मंगल काली भद्रकाली कपालिनी । दुर्गा शिवा क्षमा धात्री स्वाहा स्वधा नमोऽस्तुते ॥
(Sarvamaṅgalamāṅgalyē śivē sarvārthasādhikē . śaraṇyē tryambakē gauri nārāyaṇi namō'stu tē.
Oṃ jayantī mangala kālī bhadrakālī kapālinī . durgā śivā ksamā dhātrī svāhā svadhā namō'stutē.)
YANTRA
Goddesses play an important role in the study and practice of Tantra Yoga, and are affirmed to be as central to discerning the nature of reality as are the male deities. Although Parvati is often said to be the recipient and student of Shiva's wisdom in the form of Tantras, it is Kali who seems to dominate much of the Tantric iconography, texts, and rituals. In many sources Kāli is praised as the highest reality or greatest of all deities. The Nirvana-tantra says the gods Brahma, Vishnu, and Shiva all arise from her like bubbles in the sea, ceaselessly arising and passing away, leaving their original source unchanged. The Niruttara-tantra and the Picchila-tantra declare all of Kāli's mantras to be the greatest and the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra all proclaim Kāli vidyas (manifestations of Mahadevi, or "divinity itself"). They declare her to be an essence of her own form (svarupa) of the Mahadevi.In the Mahanirvana-tantra, Kāli is one of the epithets for the primordial sakti, and in one passage Shiva praises her:At the dissolution of things, it is Kāla [Time]. Who will devour all, and by reason of this He is called Mahākāla [an epithet of Lord Shiva], and since Thou devourest Mahākāla Himself, it is Thou who art the Supreme Primordial Kālika. Because Thou devourest Kāla, Thou art Kāli, the original form of all things, and because Thou art the Origin of and devourest all things Thou art called the Adya [the Primordial One]. Re-assuming after Dissolution Thine own form, dark and formless, Thou alone remainest as One ineffable and inconceivable. Though having a form, yet art Thou formless; though Thyself without beginning, multiform by the power of Maya, Thou art the Beginning of all, Creatrix, Protectress, and Destructress that Thou art. The figure of Kāli conveys death, destruction, and the consuming aspects of reality. As such, she is also a "forbidden thing", or even death itself. In the Pancatattva ritual, the sadhaka boldly seeks to confront Kali, and thereby assimilates and transforms her into a vehicle of salvation. This is clear in the work of the Karpuradi-stotra, a short praise of Kāli describing the Pancatattva ritual unto her, performed on cremation grounds. (Samahana-sadhana)He, O Mahākāli who in the cremation-ground, naked, and with dishevelled hair, intently meditates upon Thee and recites Thy mantra, and with each recitation makes offering to Thee of a thousand Akanda flowers with seed, becomes without any effort a Lord of the earth. Oh Kāli, whoever on Tuesday at midnight, having uttered Thy mantra, makes offering even but once with devotion to Thee of a hair of his Shakti [his energy/female companion] in the cremation-ground, becomes a great poet, a Lord of the earth, and ever goes mounted upon an elephant.The Karpuradi-stotra clearly indicates that Kāli is more than a terrible, vicious, slayer of demons who serves Durga or Shiva. Here, she is identified as the supreme mistress of the universe, associated with the five elements. In union with Lord Shiva, she creates and destroys worlds. Her appearance also takes a different turn, befitting her role as ruler of the world and object of meditation. In contrast to her terrible aspects, she takes on hints of a more benign dimension. She is described as young and beautiful, has a gentle smile, and makes gestures with her two right hands to dispel any fear and offer boons. The more positive features exposed offer the distillation of divine wrath into a goddess of salvation, who rids the sadhaka of fear. Here, Kali appears as a symbol of triumph over death.
BENGALI TRADITION
Kali is also a central figure in late medieval Bengali devotional literature, with such devotees as Ramprasad Sen (1718–75). With the exception of being associated with Parvati as Shiva's consort, Kāli is rarely pictured in Hindu legends and iconography as a motherly figure until Bengali devotions beginning in the early eighteenth century. Even in Bengāli tradition her appearance and habits change little, if at all.
The Tantric approach to Kāli is to display courage by confronting her on cremation grounds in the dead of night, despite her terrible appearance. In contrast, the Bengali devotee appropriates Kāli's teachings adopting the attitude of a child, coming to love her unreservedly. In both cases, the goal of the devotee is to become reconciled with death and to learn acceptance of the way that things are. These themes are well addressed in Rāmprasād's work. Rāmprasād comments in many of his other songs that Kāli is indifferent to his wellbeing, causes him to suffer, brings his worldly desires to nothing and his worldly goods to ruin. He also states that she does not behave like a mother should and that she ignores his pleas:
Can mercy be found in the heart of her who was born of the stone? [a reference to Kali as the daughter of Himalaya]
Were she not merciless, would she kick the breast of her lord?
Men call you merciful, but there is no trace of mercy in you, Mother.
You have cut off the heads of the children of others, and these you wear as a garland around your neck.
It matters not how much I call you "Mother, Mother." You hear me, but you will not listen.
To be a child of Kāli, Rāmprasād asserts, is to be denied of earthly delights and pleasures. Kāli is said to refrain from giving that which is expected. To the devotee, it is perhaps her very refusal to do so that enables her devotees to reflect on dimensions of themselves and of reality that go beyond the material world.
A significant portion of Bengali devotional music features Kāli as its central theme and is known as Shyama Sangeet ("Music of the Night"). Mostly sung by male vocalists, today even women have taken to this form of music. One of the finest singers of Shyāma Sāngeet is Pannalal Bhattacharya.
In Bengal, Kāli is venerated in the festival Kali Puja, the new moon day of Ashwin month which coincides with Diwali festival.
In a unique form of Kāli worship, Shantipur worships Kāli in the form of a hand painted image of the deity known as Poteshwari (meaning the deity drawn on a piece of cloth).
LEGENDS
SLAYER AND RAKTABIJA
In Kāli's most famous legend, Devi Durga (Adi Parashakti) and her assistants, the Matrikas, wound the demon Raktabija, in various ways and with a variety of weapons in an attempt to destroy him. They soon find that they have worsened the situation for with every drop of blood that is dripped from Raktabija he reproduces a clone of himself. The battlefield becomes increasingly filled with his duplicates. Durga, in need of help, summons Kāli to combat the demons. It is said, in some versions, that Goddess Durga actually assumes the form of Goddess Kāli at this time. The Devi Mahatmyam describes:
Out of the surface of her (Durga's) forehead, fierce with frown, issued suddenly Kali of terrible countenance, armed with a sword and noose. Bearing the strange khatvanga (skull-topped staff ), decorated with a garland of skulls, clad in a tiger's skin, very appalling owing to her emaciated flesh, with gaping mouth, fearful with her tongue lolling out, having deep reddish eyes, filling the regions of the sky with her roars, falling upon impetuously and slaughtering the great asuras in that army, she devoured those hordes of the foes of the devas.
Kali consumes Raktabija and his duplicates, and dances on the corpses of the slain. In the Devi Mahatmya version of this story, Kali is also described as a Matrika and as a Shakti or power of Devi. She is given the epithet Cāṃuṇḍā (Chamunda), i.e. the slayer of the demons Chanda and Munda. Chamunda is very often identified with Kali and is very much like her in appearance and habit.
DAKSHINA KALI
In her most famous pose as Daksinakali, popular legends say that Kali, drunk on the blood of her victims, is about to destroy the whole universe when, urged by all the gods, Shiva lies in her way to stop her, and she steps upon his chest. Recognizing Shiva beneath her feet, she calms herself. Though not included in any of the puranas, popular legends state that Kali was ashamed at the prospect of keeping her husband beneath her feet and thus stuck her tongue out in shame. The Devi-Bhagavata Purana, which goes into great depths about the goddess Kali, reveals the tongue's actual symbolism.
The characteristic icons that depict Kali are the following; unbridled matted hair, open blood shot eyes, open mouth and a drooping tongue; in her hands, she holds a Khadga (bent sword or scimitar) and a human head; she has a girdle of human hands across her waist, and Shiva lies beneath her feet. The drooping out-stuck tongue represents her blood-thirst. Lord Shiva beneath her feet represents matter, as Kali energy. The depiction of Kali on Shiva shows that without energy, matter lies "dead". This concept has been simplified to a folk-tale depicting a wife placing her foot
on her husband and sticking her tongue out in shame. In tantric contexts, the tongue is seen to denote the element (guna) of rajas (energy and action) controlled by sattva.
If Kali steps on Shiva with her right foot and holds the sword in her left hand, she is considered to be Dakshina Kali. The Dakshina Kali Temple has important religious associations with the Jagannath Temple and it is believed that Daksinakali is the guardian of the kitchen of the Lord Jagannath Temple. Puranic tradition says that in Puri, Lord Jagannath is regarded as Daksinakalika. Goddess Dakshinakali plays an important role in the 'Niti' of Saptapuri Amavasya.
One South Indian tradition tells of a dance contest between Shiva and Kali. After defeating the two demons Sumbha and Nisumbha, Kali takes up residence in the forest of Thiruvalankadu or Thiruvalangadu. She terrorizes the surrounding area with her fierce, disruptive nature. One of Shiva's devotees becomes distracted while performing austerities, and asks Shiva to rid the forest of the destructive goddess. When Shiva arrives, Kali threatens him, and Shiva challenges Kali to a dance contest, wherein Kali matches Shiva until Shiva takes the "Urdhvatandava" step, vertically raising his right leg. Kali refuses to perform this step, which would not befit her as a woman, and becomes pacified.
SMASHAN KALI
If the Kali steps out with the left foot and holds the sword in her right hand, she is the terrible form of Mother, the Smashan Kali of the cremation ground. She is worshiped by tantrics, the followers of Tantra, who believe that one's spiritual discipline practiced in a smashan (cremation ground) brings success quickly. Sarda Devi, the consort of Ramakrishna Paramhansa, worshipped Smashan Kali at Dakshineshwar.
MATERNAL KALI
At the time of samundra manthan when amrit came out, along with that came out poison which was going to destroy the world hence on the request of all the gods, Lord Shiva drank it to save the world but as he is beyond death he didn't die but was very much in pain due to the poison effect hence he became a child so that Kali can feed him with her milk which will sooth out the poison effect.
MAHAKALI
Mahakali (Sanskrit: Mahākālī, Devanagari: महाकाली), literally translated as Great Kali, is sometimes considered as a greater form of Kali, identified with the Ultimate reality of Brahman. It can also be used as an honorific of the Goddess Kali, signifying her greatness by the prefix "Mahā-". Mahakali, in Sanskrit, is etymologically the feminized variant of Mahakala or Great Time (which is interpreted also as Death), an epithet of the God Shiva in Hinduism. Mahakali is the presiding Goddess of the first episode of the Devi Mahatmya. Here she is depicted as Devi in her universal form as Shakti. Here Devi serves as the agent who allows the cosmic order to be restored.
Kali is depicted in the Mahakali form as having ten heads, ten arms, and ten legs. Each of her ten hands is carrying a various implement which vary in different accounts, but each of these represent the power of one of the Devas or Hindu Gods and are often the identifying weapon or ritual item of a given Deva. The implication is that Mahakali subsumes and is responsible for the powers that these deities possess and this is in line with the interpretation that Mahakali is identical with Brahman. While not displaying ten heads, an "ekamukhi" or one headed image may be displayed with ten arms, signifying the same concept: the powers of the various Gods come only through Her grace.
ICONOGRAPHY
Kali is portrayed mostly in two forms: the popular four-armed form and the ten-armed Mahakali form. In both of her forms, she is described as being black in color but is most often depicted as blue in popular Indian art. Her eyes are described as red with intoxication, and in absolute rage, her hair is shown disheveled, small fangs sometimes protrude out of her mouth, and her tongue is lolling. She is often shown naked or just wearing a skirt made of human arms and a garland of human heads. She is also accompanied by serpents and a jackal while standing on a seemingly dead Shiva, usually right foot forward to symbolize the more popular Dakshinamarga or right-handed path, as opposed to the more infamous and transgressive Vamamarga or left-handed path.
In the ten-armed form of Mahakali she is depicted as shining like a blue stone. She has ten faces, ten feet, and three eyes for each head. She has ornaments decked on all her limbs. There is no association with Shiva.
The Kalika Purana describes Kali as possessing a soothing dark complexion, as perfectly beautiful, riding a lion, four-armed, holding a sword and blue lotuses, her hair unrestrained, body firm and youthful.
In spite of her seemingly terrible form, Kali Ma is often considered the kindest and most loving of all the Hindu goddesses, as she is regarded by her devotees as the Mother of the whole Universe. And because of her terrible form, she is also often seen as a great protector. When the Bengali saint Ramakrishna once asked a devotee why one would prefer to worship Mother over him, this devotee rhetorically replied, "Maharaj", when they are in trouble your devotees come running to you. But, where do you run when you are in trouble?"
According to Ramakrishna, darkness is the Ultimate Mother, or Kali:
My Mother is the principle of consciousness. She is Akhanda Satchidananda;
indivisible Reality, Awareness, and Bliss. The night sky between the stars is perfectly black.
The waters of the ocean depths are the same; The infinite is always mysteriously dark.
This inebriating darkness is my beloved Kali.
—Sri Ramakrishna
This is clear in the works of such contemporary artists as Charles Wish, and Tyeb Mehta, who sometimes take great liberties with the traditional, accepted symbolism, but still demonstrate a true reverence for the Shakta sect.
POPULAR FORM
Classic depictions of Kali share several features, as follows:
Kali's most common four armed iconographic image shows each hand carrying variously a sword, a trishul (trident), a severed head, and a bowl or skull-cup (kapala) catching the blood of the severed head.
Two of these hands (usually the left) are holding a sword and a severed head. The Sword signifies Divine Knowledge and the Human Head signifies human Ego which must be slain by Divine Knowledge in order to attain Moksha. The other two hands (usually the right) are in the abhaya (fearlessness) and varada (blessing) mudras, which means her initiated devotees (or anyone worshipping her with a true heart) will be saved as she will guide them here and in the hereafter.
She has a garland consisting of human heads, variously enumerated at 108 (an auspicious number in Hinduism and the number of countable beads on a Japa Mala or rosary for repetition of Mantras) or 51, which represents Varnamala or the Garland of letters of the Sanskrit alphabet, Devanagari. Hindus believe Sanskrit is a language of dynamism, and each of these letters represents a form of energy, or a form of Kali. Therefore, she is generally seen as the mother of language, and all mantras.
She is often depicted naked which symbolizes her being beyond the covering of Maya since she is pure (nirguna) being-consciousness-bliss and far above prakriti. She is shown as very dark as she is brahman in its supreme unmanifest state. She has no permanent qualities - she will continue to exist even when the universe ends. It is therefore believed that the concepts of color, light, good, bad do not apply to her - she is the pure, un-manifested energy, the Adi-shakti.
Kali as the Symbol of Creation , Freedom , Preservation and Destruction
The head that hangs in Kali's hand is a symbol of Ego and the scimitar which she is holding represents power and energy.It is believed that Kali is protecting the human race by that scimitar and also destroying the negativity and ego within human being. The body lying under Kali symbolizes ruination, is actually a form of Shiva. Kali steps her leg on the chest of the body and suppress ruination . Since she is standing on the pure white chest of Lord Shiva who, as pure primal awareness, lays in a passive reclining position, peacefully lies with his eyes half open in a state of bliss. Her hair is long, black and flowing freely depicting Her freedom from convention and the confines of conceptualization. The white teeth which Kali has stands for conscience and her red tongue represents greed. By pressing her white teeth on her tongue Kali refers to control greed.The goddess may appear terrible from outside but every symbol in Kali signifies truth of life. Since the earth was created out of darkness, the dark black color of Kali symbolizes the color from which everything was born. Her right hand side arms she shows the Abhaya mudra(gesture of fearlessness) and Vara mudra (gesture of welcome and charity) respectively . But on the other arm in left side she holds a bloody scimitar and a severed head depicting destruction and end of ego.
Kali as the Symbol of Mother Nature
The name Kali means Kala or force of time. When there were neither the creation, nor the sun, the moon, the planets, and the earth, there was only darkness and everything was created from the darkness. The Dark appearance of kali represents the darkness from which everything was born. Her complexion is deep blue, like the sky and ocean water as blue. As she is also the goddess of Preservation Kali is worshiped as mother to preserve the nature.Kali is standing calm on Shiva, her appearance represents the preservation of mother nature. Her free, long and black hair represents nature's freedom from civilization. Under the third eye of kali, the signs of both sun, moon and fire are visible which represent the driving forces of nature.
SHIVA IN KALI ICONOGRAPHY
In both these images she is shown standing on the prone, inert or dead body of Shiva. There is a legend for the reason behind her standing on what appears to be Shiva's corpse, which translates as follows:
Once Kali had destroyed all the demons in battle, she began a terrific dance out of the sheer joy of victory. All the worlds or lokas began to tremble and sway under the impact of her dance. So, at the request of all the Gods, Shiva himself asked her to desist from this behavior. However, she was too intoxicated to listen. Hence, Shiva lay like a corpse among the slain demons in order to absorb the shock of the dance into himself. When Kali eventually stepped upon Shiva, she realized she was trampling and hurting her husband and bit her tongue in shame.
The story described here is a popular folk tale and not described or hinted in any of the puranas. The puranic interpretation is as follows:
Once, Parvati asks Shiva to chose the one form among her 10 forms which he likes most. To her surprise, Shiva reveals that he is most comfortable with her Kali form, in which she is bereft of her jewellery, her human-form, her clothes, her emotions and where she is only raw, chaotic energy, where she is as terrible as time itself and even greater than time. As Parvati takes the form of Kali, Shiva lies at her feet and requests her to place her foot on his chest, upon his heart. Once in this form, Shiva requests her to have this place, below her feet in her iconic image which would be worshiped throughout.
This idea has been explored in the Devi-Bhagavata Purana [28] and is most popular in the Shyama Sangeet, devotional songs to Kali from the 12th to 15th centuries.
The Tantric interpretation of Kali standing on top of her husband is as follows:
The Shiv tattava (Divine Consciousness as Shiva) is inactive, while the Shakti tattava (Divine Energy as Kali) is active. Shiva and Kali represent Brahman, the Absolute pure consciousness which is beyond all names, forms and activities. Kali, on the other hand, represents the potential (and manifested) energy responsible for all names, forms and activities. She is his Shakti, or creative power, and is seen as the substance behind the entire content of all consciousness. She can never exist apart from Shiva or act independently of him, just as Shiva remains a mere corpse without Kali i.e., Shakti, all the matter/energy of the universe, is not distinct from Shiva, or Brahman, but is rather the dynamic power of Brahman. Hence, Kali is Para Brahman in the feminine and dynamic aspect while Shiva is the male aspect and static. She stands as the absolute basis for all life, energy and beneath her feet lies, Shiva, a metaphor for mass, which cannot retain its form without energy.
While this is an advanced concept in monistic Shaktism, it also agrees with the Nondual Trika philosophy of Kashmir, popularly known as Kashmir Shaivism and associated most famously with Abhinavagupta. There is a colloquial saying that "Shiva without Shakti is Shava" which means that without the power of action (Shakti) that is Mahakali (represented as the short "i" in Devanagari) Shiva (or consciousness itself) is inactive; Shava means corpse in Sanskrit and the play on words is that all Sanskrit consonants are assumed to be followed by a short letter "a" unless otherwise noted. The short letter "i" represents the female power or Shakti that activates Creation. This is often the explanation for why She is standing on Shiva, who is either Her husband and complement in Shaktism or the Supreme Godhead in Shaivism.
To properly understand this complex Tantric symbolism it is important to remember that the meaning behind Shiva and Kali does not stray from the non-dualistic parlance of Shankara or the Upanisads. According to both the Mahanirvana and Kularnava Tantras, there are two distinct ways of perceiving the same absolute reality. The first is a transcendental plane which is often described as static, yet infinite. It is here that there is no matter, there is no universe and only consciousness exists. This form of reality is known as Shiva, the absolute Sat-Chit-Ananda - existence, knowledge and bliss. The second is an active plane, an immanent plane, the plane of matter, of Maya, i.e., where the illusion of space-time and the appearance of an actual universe does exist. This form of reality is known as Kali or Shakti, and (in its entirety) is still specified as the same Absolute Sat-Chit-Ananda. It is here in this second plane that the universe (as we commonly know it) is experienced and is described by the Tantric seer as the play of Shakti, or God as Mother Kali.
From a Tantric perspective, when one meditates on reality at rest, as absolute pure consciousness (without the activities of creation, preservation or dissolution) one refers to this as Shiva or Brahman. When one meditates on reality as dynamic and creative, as the Absolute content of pure consciousness (with all the activities of creation, preservation or dissolution) one refers to it as Kali or Shakti. However, in either case the yogini or yogi is interested in one and the same reality - the only difference being in name and fluctuating aspects of appearance. It is this which is generally accepted as the meaning of Kali standing on the chest of Shiva.
Although there is often controversy surrounding the images of divine copulation, the general consensus is benign and free from any carnal impurities in its substance. In Tantra the human body is a symbol for the microcosm of the universe; therefore sexual process is responsible for the creation of the world. Although theoretically Shiva and Kali (or Shakti) are inseparable, like fire and its power to burn, in the case of creation they are often seen as having separate roles. With Shiva as male and Kali as female it is only by their union that creation may transpire. This reminds us of the prakrti and purusa doctrine of Samkhya wherein prakāśa- vimarśa has no practical value, just as without prakrti, purusa is quite inactive. This (once again) stresses the interdependencies of Shiva and Shakti and the vitality of their union.
Gopi Krishna proposed that Kali standing on the dead Shiva or Shava (Sanskrit for dead body) symbolised the helplessness of a person undergoing the changing process (psychologically and physiologically) in the body conducted by the Kundalini Shakti.
DEVELOPMENT
In the later traditions, Kali has become inextricably linked with Shiva. The unleashed form of Kali often becomes wild and uncontrollable, and only Shiva is able to tame her just as only Kali can tame Shiva. This is both because she is often a transformed version of one of his consorts and because he is able to match her wildness.
The ancient text of Kali Kautuvam describes her competition with Shiva in dance, from which the sacred 108 Karanas appeared. Shiva won the competition by acting the urdva tandava, one of the Karanas, by raising his feet to his head. Other texts describe Shiva appearing as a crying infant and appealing to her maternal instincts. While Shiva is said to be able to tame her, the iconography often presents her dancing on his fallen body, and there are accounts of the two of them dancing together, and driving each other to such wildness that the world comes close to unravelling.
Shiva's involvement with Tantra and Kali's dark nature have led to her becoming an important Tantric figure. To the Tantric worshippers, it was essential to face her Curse, the terror of death, as willingly as they accepted Blessings from her beautiful, nurturing, maternal aspect. For them, wisdom meant learning that no coin has only one side: as death cannot exist without life, so life cannot exist without death. Kali's role sometimes grew beyond that of a chaos - which could be confronted - to that of one who could bring wisdom, and she is given great metaphysical significance by some Tantric texts. The Nirvāna-tantra clearly presents her uncontrolled nature as the Ultimate Reality, claiming that the trimurti of Brahma, Vishnu and Rudra arise and disappear from her like bubbles from the sea. Although this is an extreme case, the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra declare her the svarupa (own-being) of the Mahadevi (the great Goddess, who is in this case seen as the combination of all devis).The final stage of development is the worshipping of Kali as the Great Mother, devoid of her usual violence. This practice is a break from the more traditional depictions. The pioneers of this tradition are the 18th century Shakta poets such as Ramprasad Sen, who show an awareness of Kali's ambivalent nature. Ramakrishna, the 19th century Bengali saint, was also a great devotee of Kali; the western popularity of whom may have contributed to the more modern, equivocal interpretations of this Goddess. Rachel McDermott's work, however, suggests that for the common, modern worshipper, Kali is not seen as fearful, and only those educated in old traditions see her as having a wrathful component. Some credit to the development of Devi must also be given to Samkhya. Commonly referred to as the Devi of delusion, Mahamaya or Durga, acting in the confines of (but not being bound by) the nature of the three gunas, takes three forms: Maha-Kali, Maha-Lakshmi and Maha-Saraswati, being her tamas-ika, rajas-ika and sattva-ika forms. In this sense, Kali is simply part of a larger whole.
Like Sir John Woodroffe and Georg Feuerstein, many Tantric scholars (as well as sincere practitioners) agree that, no matter how propitious or appalling you describe them, Shiva and Devi are simply recognizable symbols for everyday, abstract (yet tangible) concepts such as perception, knowledge, space-time, causation and the process of liberating oneself from the confines of such things. Shiva, symbolizing pure, absolute consciousness, and Devi, symbolizing the entire content of that consciousness, are ultimately one and the same - totality incarnate, a micro-macro-cosmic amalgamation of all subjects, all objects and all phenomenal relations between the "two." Like man and woman who both share many common, human traits yet at the same time they are still different and, therefore, may also be seen as complementary.
Worshippers prescribe various benign and horrific qualities to Devi simply out of practicality. They do this so they may have a variety of symbols to choose from, symbols which they can identify and relate with from the perspective of their own, ever-changing time, place and personal level of unfolding. Just like modern chemists or physicists use a variety of molecular and atomic models to describe what is unperceivable through rudimentary, sensory input, the scientists of ontology and epistemology must do the same. One of the underlying distinctions of Tantra, in comparison to other religions, is that it allows the devotee the liberty to choose from a vast array of complementary symbols and rhetoric which suit one's evolving needs and tastes. From an aesthetic standpoint, nothing is interdict and nothing is orthodox. In this sense, the projection of some of Devi's more gentle qualities onto Kali is not sacrilege and the development of Kali really lies in the practitioner, not the murthi.
A TIME magazine article of October 27, 1947, used Kali as a symbol and metaphor for the human suffering in British India during its partition that year. In 1971, Ms. Magazine used an image of Kali, her multiple arms juggling modern tasks, as a symbol of modern womanhood on its inaugural issue.
Swami Vivekananda wrote his favorite poem Kali the Mother in 1898.
KALI IN NEOPAGAN AND NEW AGE PRACTICE
An academic study of Western Kali enthusiasts noted that, "as shown in the histories of all cross-cultural religious transplants, Kali devotionalism in the West must take on its own indigenous forms if it is to adapt to its new environment."[60] The adoption of Kali by the West has raised accusations of cultural appropriation:
A variety of writers and thinkers have found Kali an exciting figure for reflection and exploration, notably feminists and participants in New Age spirituality who are attracted to goddess worship. [For them], Kali is a symbol of wholeness and healing, associated especially with repressed female power and sexuality. [However, such interpretations often exhibit] confusion and misrepresentation, stemming from a lack of knowledge of Hindu history among these authors, [who only rarely] draw upon materials written by scholars of the Hindu religious tradition. The majority instead rely chiefly on other popular feminist sources, almost none of which base their interpretations on a close reading of Kali's Indian background. The most important issue arising from this discussion - even more important than the question of 'correct' interpretation - concerns the adoption of other people's religious symbols. It is hard to import the worship of a goddess from another culture: religious associations and connotations have to be learned, imagined or intuited when the deep symbolic meanings embedded in the native culture are not available.
INCARNATIONS OF KALI
Draupadi, Wife of Pandavas, was an avatar of Kali, who born to assist Lord Krishna to destroy arrogant kings of India. There is a temple dedicated to this incarnation at Banni Mata Temple at Himachal Pradesh. The vedic deity Nirriti or the Puranic deity Alakshmi is often considered as incarnations of Kali.
WIKIPEDIA
The bhavacakra (Sanskrit; Pāli: bhavacakka; Tibetan: srid pa'i 'khor lo) is a symbolic representation of saṃsāra (or cyclic existence) found on the outside walls of Tibetan Buddhist temples and monasteries in the Indo-Tibetan region. In the Mahayana Buddhism, it is believed that the drawing was designed by the Buddha himself in order to help ordinary people understand Buddhist teachings.
The bhavacakra is popularly referred to as the wheel of life, and may also be glossed as wheel of cyclic existence or wheel of becoming.
ORIGIN
Legend has it that the historical Buddha himself created the first depiction of the bhavacakra, and the story of how he gave the illustration to King Rudrāyaṇa appears in the anthology of Buddhist narratives called the Divyāvadāna.
The bhavacakra is painted on the outside walls of nearly every Tibetan Buddhist temple in Tibet and India. Dzongsar Jamyang Khyentse Rinpoche states:
One of the reasons why the Wheel of Life was painted outside the monasteries and on the walls (and was really encouraged even by the Buddha himself) was to teach this very profound Buddhist philosophy of life and perception to more simple-minded farmers or cowherds. So these images on the Wheel of Life are just to communicate to the general audience.
EXPLANATION OF THE DIAGRAM
OVERVIEW
The meanings of the main parts of the diagram are:
The images in the hub of the wheel represent the three poisons of ignorance, attachment and aversion.
The second layer represents karma.
The third layer represents the six realms of samsara.
The fourth layer represents the twelve links of dependent origination.
The fierce figure holding the wheel represents impermanence.
The moon above the wheel represents liberation from samsara or cyclic existence.
The Buddha pointing to the moon indicates that liberation is possible.
Symbolically, the three inner circles, moving from the center outward, show that the three poisons of ignorance, attachment, and aversion give rise to positive and negative actions; these actions and their results are called karma. Karma in turn gives rise to the six realms, which represent the different types of suffering within samsara.
The fourth and outer layer of the wheel symbolizes the twelve links of dependent origination; these links indicate how the sources of suffering - the three poisons and karma - produce lives within cyclic existence.
The fierce being holding the wheel represents impermanence; this symbolizes that the entire process of samsara or cyclic existence is impermanent, transient, constantly changing. The moon above the wheel indicates liberation. The Buddha is pointing to the moon, indicating that liberation from samsara is possible.
HUB: THE THREE POISONS
In the hub of the wheel are three animals: a pig, a snake, and a bird. They represent the three poisons of ignorance, aversion, and attachment, respectively. The pig stands for ignorance; this comparison is based on the Indian concept of a pig being the most foolish of animals, since it sleeps in the dirtiest places and eats whatever comes to its mouth. The snake represents aversion or anger; this is because it will be aroused and strike at the slightest touch. The bird represents attachment (also translated as desire or clinging). The particular bird used in this diagram represents an Indian bird that is very attached to its partner. These three animals represent the three poisons, which are the core of the bhavacakra. From these three poisons, the whole cycle of existence evolves.
In many drawings of the wheel, the snake and bird are shown as coming out of the mouth of the pig, indicating that aversion and attachment arise from ignorance. The snake and bird are also shown grasping the tail of the pig, indicating that they in turn promote greater ignorance.
Under the influence of the three poisons, beings create karma, as shown in the next layer of the circle.
SECOND LAYER: KARMA
The second layer of the wheel shows two-half circles:
One half-circle (usually light) shows contented people moving upwards to higher states, possibly to the higher realms.
The other half-circle (usually dark) shows people in a miserable state being led downwards to lower states, possibly to the lower realms.
These images represent karma, the law of cause and effect. The light half-circle indicates people experiencing the results of positive actions. The dark half-circle indicates people experiencing the results of negative actions.
Ringu Tulku states:
We create karma in three different ways, through actions that are positive, negative, or neutral. When we feel kindness and love and with this attitude do good things, which are beneficial to both ourselves and others, this is positive action. When we commit harmful deeds out of equally harmful intentions, this is negative action. Finally, when our motivation is indifferent and our deeds are neither harmful or beneficial, this is neutral action. The results we experience will accord with the quality of our actions.
Propelled by their karma, beings take rebirth in the six realms of samsara, as shown in the next layer of the circle.
THIRD LAYER: THE SIX REALMS OF SAMSARA
OVERVIEW
The third layer of the wheel is divided into six sections that represent the six realms of samsara. These six realms are divided into three higher realms and three lower realms.
The three higher realms are shown in the top half of the circle; the higher realms consist of the god realm, the demi-god realm and the human realm. The god realm is shown in the top middle and the human realm and demi-god realms are on either side of the god realm.
The three lower realms are shown in the bottom half of the circle; the lower realms consist of the hell realm, the animal realm and the hungry ghost realm. The hell realm is shown in the bottom middle of the circle, with the animal realm and hungry ghost realm on either side of the hell realm.
WHAT IS SAMSARA?
The six realms are six different types of rebirth that beings can enter into, each representing different types of suffering. Samsara, or cyclic existence, refers to the process of cycling through one rebirth after another.
Patrul Rinpoche states:
The term samsara, the wheel or round of existence, is used here to mean going round and round from one place to another in a circle, like a potter's wheel, or the wheel of a water mill. When a fly is trapped in a closed jar, no matter where it flies, it can not get out. Likewise, whether we are born in the higher or lower realms, we are never outside samsara. The upper part of the jar is like the higher realms of gods and men, and the lower part like the three unfortunate realms. It is said that samsara is a circle because we turn round and round, taking rebirth in one after another of the six realms as a result of our own actions, which, whether positive or negative, are tainted by clinging.
A BRIEF DESCRIPTION OF THE SIX REALMS
Six realms of existence are identified in the Buddhist teachings: gods, demi-gods, humans, animals, hungry ghosts and hells. These realms can be understood on a psychological level, or as aspects of Buddhist cosmology.
These six realms can be divided into three higher realms and three lower realms. The three higher realms are:
GOD REALM: the gods lead long and enjoyable lives full of pleasure and abundance, but they spend their lives pursuing meaningless distractions and never think to practice the dharma. When death comes to them, they are completely unprepared; without realizing it, they have completely exhausted their good karma (which was the cause for being reborn in the god realm) and they suffer through being reborn in the lower realms.
DEMI-GODS REALM: the demi-gods have pleasure and abundance almost as much as the gods, but they spend their time fighting among themselves or making war on the gods. When they make war on the gods, they always lose, since the gods are much more powerful. The demi-gods suffer from constant fighting and jealousy, and from being killed and wounded in their wars with each other and with the gods.
HUMAN REALM: humans suffer from hunger, thirst, heat, cold, separation from friends, being attacked by enemies, not getting what they want, and getting what they don't want. They also suffer from the general sufferings of birth, old age, sickness and death. Yet the human realm is considered to be the most suitable realm for practicing the dharma, because humans are not completely distracted by pleasure (like the gods or demi-gods) or by pain and suffering (like the beings in the lower realms).
The three lower realms are:
ANIMAL REALM: wild animals suffer from being attacked and eaten by other animals; they generally lead lives of constant fear. Domestic animals suffer from being exploited by humans; for example, they are slaughtered for food, overworked, and so on.
HUNGRY GHOST REALM: hungry ghosts suffer from extreme hunger and thirst. They wander constantly in search of food and drink, only to be miserably frustrated any time they come close to actually getting what they want. For example, they see a stream of pure, clear water in the distance, but by the time they get there the stream has dried up. Hungry ghosts have huge bellies and long, thin necks. On the rare occasions that they do manage to find something to eat or drink, the food or water burns their neck as it goes down to their belly, causing them intense agony.
HELL REALM: hell beings endure unimaginable suffering for eons of time. There are actually eighteen different types of hells, each inflicting a different kind of torment. In the hot hells, beings suffer from unbearable heat and continual torments of various kinds. In the cold hells, beings suffer from unbearable cold and other torments.
Generally speaking, each realm is said to be the result of one of the six main negative emotions: pride, jealousy, desire, ignorance, greed, and anger. Dzongsar Khyentse states:
So we have six realms. Loosely, you can say when the perception comes more from aggression, you experience things in a hellish way. When your perception is filtered through attachment, grasping or miserliness, you experience the hungry ghost realm. When your perception is filtered through ignorance, then you experience the animal realm. When you have a lot of pride, you are reborn in the god realm. When you have jealousy, you are reborn in the asura (demi-god) realm. When you have a lot of passion, you are reborn in the human realm.
Among the six realms, the human realm is considered to offer the best opportunity to practice the dharma. Dzongsar Khyentse states:
If we need to judge the value of these six realms, the Buddhists would say the best realm is the human realm. Why is this the best realm? Because you have a choice ... The gods don't have a choice. Why? They're too happy. When you are too happy you have no choice. You become arrogant. The hell realm: no choice, too painful. The human realm: not too happy and also not too painful. When you are not so happy and not in so much pain, what does that mean? A step closer to the normality of mind, remember? When you are really, really excited and in ecstasy, there is no normality of mind. And when you are totally in pain, you don't experience normality of mind either. So someone in the human realm has the best chance of acquiring that normality of mind. And this is why in Buddhist prayers you will always read: ideally may we get out of this place, but if we can't do it within this life, may we be reborn in the human realm, not the others.
Sometimes, the wheel is represented as only having five realms because the God realm and the Demi-god realm are combined into a single realm.
In some representations of the wheel, there is a buddha or bodhisattva depicted within each realm, trying to help sentient beings find their way to nirvana.
SANSKRIT TERMS FOR THE SIX REALMS
The Sanskrit terms for the six realms are:
Deva realm: God realm
Asura realm: Demi-god realm
Manuṣya realm: Human realm
Tiryagyoni realm: Animal realm
Preta realm: Hungry Ghost realm
Naraka realm: Hell realm
OUTER RIM: THE TWELVE LINKS
The outer rim of the wheel is divided into twelve sections that represent the Twelve Nidānas. As previously stated, the three inner layers of the wheel show that the three poisons lead to karma, which leads to the suffering of the six realms. The twelve links of the outer rim show how this happens - by presenting the process of cause and effect in detail.
These twelve links can be understood to operate on an outer or inner level.
On the outer level, the twelve links can be seen to operate over several lifetimes; in this case, these links show how our past lives influence our current lifetime, and how our actions in this lifetime influence our future lifetimes.
On the inner level, the twelve links can be understood to operate in every moment of existence in an interdependent manner. On this level, the twelve links can be applied to show the effects of one particular action.
By contemplating on the twelve links, one gains greater insight into the workings of karma; this insight enables us to begin to unravel our habitual way of thinking and reacting.
The twelve causal links, paired with their corresponding symbols, are:
Avidyā lack of knowledge – a blind person, often walking, or a person peering out
Saṃskāra constructive volitional activity – a potter shaping a vessel or vessels
Vijñāna consciousness – a man or a monkey grasping a fruit
Nāmarūpa name and form (constituent elements of mental and physical existence) – two men afloat in a boat
Ṣaḍāyatana six senses (eye, ear, nose, tongue, body, and mind) – a dwelling with six windows
Sparśa contact – lovers consorting, kissing, or entwined
Vedanā pain – an arrow to the eye
Tṛṣṇa thirst – a drinker receiving drink
Upādāna grasping – a man or a monkey picking fruit
Bhava coming to be – a couple engaged in intercourse, a standing, leaping, or reflective person
Jāti being born – woman giving birth
Jarāmaraṇa old age and death – corpse being carried
THE FIGURE HOLDING THE WHEEL: IMPERMANENCE
The wheel is being held by a fearsome figure who represents impermanence. The 14th Dalai Lama states:The fierce being holding the wheel symbolizes impermanence, which is why the being is a wrathful monster, though there is no need for it to be drawn with ornaments and so forth ... Once I had such a painting drawn with a skeleton rather than a monster, in order to symbolize impermanence more clearly.
This figure is most commonly depicted as Yama, the lord of death. Regardless of the figure depicted, the inner meaning remains the same–that the entire process of cyclic existence (samsara) is transient; everything within this wheel is constantly changing.
Yama has the following attributes:
He wears a crown of five skulls that symbolize the impermanence of the five aggregates. (The skulls are also said to symbolize the five poisons.)
He has a third eye that symbolizes the wisdom of understanding impermanence.
He is sometimes shown adorned with a tiger skin, which symbolizes fearfulness. (The tiger skin is typically seen hanging beneath the wheel.)
His four limbs (that are clutching the wheel) symbolize the sufferings of birth, old age, sickness, and death.
THE MOON: LIBERATION
Above the wheel is an image of the moon; the moon represents liberation from the sufferings of samsara.
Thubten Chodron states:
The moon is nirvana [i.e. liberation]. Nirvana is the cessation of all the unsatisfactory experiences and their causes in such a way that they can no longer occur again. It's the removal, the final absence, the cessation of those things, their non-arising. The Buddha is pointing us to that.
Chögyam Trungpa states:
The truth of cessation is a personal discovery. It is not mystical and does not have any connotations of religion or psychology. It is simply your experience ... Likewise, cessation is not just a theoretical discovery, but an experience that is very real to you–a sudden gain. It is like experiencing instantaneous good health: you have no cold, no flu, no aches, and no pains in your body. You feel perfectly well, absolutely refreshed and wakeful! Such an experience is possible.
Some drawings may show an image of a "pure land" to indicate liberation, rather than a moon.
THE BUDDHA POINTING TO THE MOON: THE PATH TO LIBERATION
The upper part of the drawing also shows an image of the Buddha pointing toward the moon; this represents the path to liberation.
Thubten Chodron states:
So the Buddha's gesture is like the path to enlightenment. It's not that the Buddha is the cause of nirvana. The Buddha is a cooperative condition of our nirvana. He indicates the path to us, he points out to us what to practice and what to abandon in order to be liberated. When we follow the path, we get the result, which is nirvana.
Chögyam Trungpa states:
The nature of the path is more like an exploration or an expedition than following a path that has already been built. When people hear that they should follow the path, they might think that a ready-make system exists, and that individual expressions are not required. They may think that one does not have to surrender or give or open. But when you actually begin to tread on the path, you realize that you have to clear out the jungle and all the trees, underbrush, and obstacles growing in front of you. You have to bypass tigers and elephants and poisonous snakes.
Mark Epstein states:
The entire Wheel of Life is but a representation of the possibility of transforming suffering by changing the way we relate to it. As the Buddha taught in his final exhortation to his faithful attendant Ananda, it is only through becoming a "lamp unto yourself" that enlightenment can be won. Liberation from the Wheel of Life does not mean escape, the Buddha implied. It means clear perception of oneself, of the entire range of the human experience ...
According to the Buddhist tradition, the Buddha told his followers:
I have shown you the path that leads to liberation
But you should know that liberation depends upon yourself.
INSCRIPTION
Drawings of the Bhavacakra usually contain an inscription consisting of a few lines of text that explain the process that keeps us in samara and how to reverse that process.
PSYCHOLOGICAL INTERPRETATION
From a psychological point of view, different karmic actions contribute to one's metaphorical existence in different realms, or rather, different actions reinforce personal characteristics described by the realms.
Mark Epstein states:
The core question of Buddhist practice, after all, is the psychological one of "Who am I?" Investigating this question requires exploration of the entire wheel. Each realm becomes not so much a specific place but rather a metaphor for a different psychological state, with the entire wheel becoming a representation of neurotic suffering.
WITHIN THE THERAVADA TRADITION
T. B. Karunaratne states:
Though in Theravāda literature there is no mention of an actual pictorial execution of a "Wheel of Life," yet the concept of comparing Dependent Origination to a wheel is not unknown. In the Path of Purification (Visuddhimagga), the famous commentator Buddhaghosa Acariya says:
"It is the beginningless round of rebirths that is called the 'Wheel of the round of rebirths' (saṃsāracakka). Ignorance (avijjā) is its hub (or nave) because it is its root. Ageing-and-death (jarā-maraṇa) is its rim (or felly) because it terminates it. The remaining ten links (of the Dependent Origination) are its spokes (i.e. karma formations [saṅkhāra] up to process of becoming [bhava])."
WIKIPEDIA
Explore Sep 29, 2011 #49
New. Fragile. Weak. It flies to a new leaf, nectars and strengthens. Its egg was laid on a rare Coontie plant, an endangered species in Florida. It has enlarged in its cocoon and emerged.
Rare. Rare. We hope it will thrive and mate as we work to plant more and more Coonties again!
The Atala butterfly is strange to photograph. The colored areas are vague at the margins so the color looks like it has been dusted on a bit carelessly. But look at its marvelous tones... deep velvety midnight blue, bright iridescent sky blue and brilliant red orange! It is very fast moving so getting a shot at all is always a thrill! Usually looks like a vibrant patch of astounding flying color and it's gone.
Interdependencies in nature once again. This marvelous creature owes its life to the Florida Coontie which was almost wiped out after being the money crop of the first Florida pioneers. Without the Coontie, this beauty will be gone.
The short, woody stem and rootstock of the Coontie grows almost completely underground and produces a terminal crown of stiff, evergreen, pinnate leaves up to 3 feet long. The brown, fleshy, erect, female or seed-bearing cones are pendent when mature. Coontie plants contain a natural toxin, which Atala larvae accumulate in their bodies and use to repel birds. Without Coontie, adult Atalas have no place to lay eggs. No eggs means no new generations.
Wild Coonties’ demise began with starch: Long before Europeans arrived in Florida, Native Americans used Coontie as a source of starch. Coontie, in fact, is a Seminole word that means “bread” or “white root” because the roots can be made into flour.
From "The Forgotten Frontier: Florida Through the Lens of Ralph Middleton Munroe" by Arva Moore Parks: 'Behind the hammock land the pine and palmetto country seemed to go on forever. Sending roots into the crevices of stone, the tall pine and its companions, the bushy palmetto and the fernlike comptie (Zamia), thrived in what seemed like solid rock. Although not as glamorous as the hammock, the pineland was the backbone of the land. The heart of the pine became the foundation of the pioneer home; the palmetto, for thatch, became the roof; and the starch made from the root of the comptie filled the pionerer's stomach."
Cootie is sporadic in pinelands and hammocks throughout nearly all peninsular Florida and the Keys. In an effort to preserve the Atala, the Coontie is being used increasingly in landscaping.
Arch Creek was an early Tequesta Indian settlement here in North Miami. Arch Creek is spanned by a natural limestone bridge. Early photographs of Miami show the bridge in all its beauty. Compromised now by encroaching housing and roadways.
The Tequesta Indians thrived in Arch Creek and the surrounding area. There was an oak hammock near the creek which provided shade as well as edible plants, nuts and berries. Biscayne Bay, less than a half mile away, was a prime food source for the Tequestas. There they caught shellfish, shark, manatee and turtle. North of the hammock were pine flatlands, which sheltered the all-important Coontie plant (Zamia integrifolia), whose roots the Indians ground to make an edible starch product. Tequesta habitation sites characteristically have midden areas or Indian garbage dumps. The gradual decomposition of refuse, including plant material and animal bones, produces a rich black soil. Many artifacts have been preserved in the soil, and archaeologists have uncovered many of them, such as bone points, shell tools and pottery shards. During their centuries of occupation (from c. 400 A.D. to c. 1200 A.D.), the Arch Creek Tequestas had what appears to be a fairly comfortable lifestyle, supported by the abundant natural resources at the site.
Around 1858 two ambitious pioneers used the creek and its natural bridge as a site for a Coontie starch mill. These early entrepreneurs learned how to clean the poisonous roots and dammed up the waterway under the bridge diverting the flow through a sluice they carved out of a solid limestone bank. The water turned a wooden wheel attached to a nail-studded grinder, which mashed the cootie roots into a paste-like pulp. The resulting starch was then soaked and strained to remove any remaining poison. Laid out in wooden racks, the starch dried quickly and the sun bleached it white. In the early 1900s, several commercial factories in South Florida processed Coontie roots for the manufacture of arrowroot biscuits. But Coontie starch was not as successful as the pioneers thought, and the mill was abandoned several years later. The water sluice was filled in and paved over and was not rediscovered until archaeologists excavated it in 1972.
Atala Eumaeus
Fairchild Tropical Botanic Garden, Miami, FL
In Chinese philosophy, the concept of yin-yang , which is often called "yin and yang",is used to describe how seemingly opposite or contrary forces are interconnected and interdependent in the natural world; and, how they give rise to each other as they interrelate to one another. Many natural dualities (such as light and dark, high and low, hot and cold, fire and water, life and death, and so on) are thought of as physical manifestations of the yin-yang concept. The concept lies at the origins of many branches of classical Chinese science and philosophy, as well as being a primary guideline of traditional Chinese medicine, and a central principle of different forms of Chinese martial arts and exercise.
Yin and yang can be thought of as complementary (instead of opposing) forces interacting to form a dynamic system in which the whole is greater than the parts. Everything has both yin and yang aspects, (for instance shadow cannot exist without light). Either of the two major aspects may manifest more strongly in a particular object, depending on the criterion of the observation.
Haven't attempted this shot in a while, time for an update if you like?
Now that the storage sidings now has it's own separate control meaning both mainlines now work interdependently while I have a shunt around.
Never satisfied, the later photo of this site shows you why?
[Una versión más legible se encontrará en la entrada correspondiente del blog, cuyo enlace se señala a continuación]
enriqueviolanevado.blogspot.com/2020/05/vocabulario-de-ge...
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El Listado de Términos publicado por la Ponencia de Geografía de España en noviembre de 2018 especifica que conceptos serán los escogidos para las pruebas de Selectividad. En el apartado de Genéricos encontramos los vocablos que se definen a continuación.
Se añaden los conceptos por referencias que han aparecido en las pruebas de selectividad desde el curso 2016-2017, año académico en el que se implantó el modelo de examen que los agregaba. El presente repertorio incluye los elegidos para el curso 2019-2020.
VOCABULARIO DE GEOGRAFÍA DE ESPAÑA
- Genéricos –
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1. Coordenadas geográficas: Conjunto de líneas que permiten determinar con exactitud la posición de un punto en la superficie terrestre, siempre que sean conocidas su latitud y su longitud.
2. Escala de un mapa: Relación entre una distancia medida sobre el mapa y la correspondiente distancia en la realidad. Las escalas más habituales son la escala gráfica y la escala numérica.
3. Globalización. Proceso incentivado por el desarrollo de los transportes y las tecnologías de la comunicación, por el que las economías y mercados adquieren una dimensión mundial y favorecen la integración e interdependencia de las distintas economías nacionales. En este desarrollo ha sido decisiva la progresiva liberalización de los intercambios de bienes, servicios, tecnología, fuerza de trabajo y capitales entre los países. La globalización se da también en otros ámbitos: social, cultural, medioambiental…
4. Latitud geográfica: Distancia angular (medida en grados) entre un punto de la superficie terrestre y el ecuador. Puede ser norte o sur. La latitud suele relacionarse con el clima al medir la inclinación de los rayos del sol. La península Ibérica se encuentra entre los 36º y los 44º de latitud norte, en la zona templada boreal.
5. Longitud geográfica: Distancia angular existente entre un punto de la superficie terrestre y el meridiano 0º o de referencia, que desde 1884 es el de Greenwich. La longitud se relaciona con el cálculo de la hora (longitud horaria). La longitud geográfica puede ser este u oeste. La Península se extiende por ambos hemisferios al ser atravesada por el meridiano 0º. Atraviesa el macizo del Monte Perdido y las localidades de Villanueva de Sigena (Huesca), Castellón de la Plana, Denia y Altea (Alicante).
6. Mapa temático: Mapa que muestra la distribución espacial de un fenómeno geográfico, ya sean objetos reales (suelos, vegetación…) o conceptos abstractos como los indicadores (natalidad, renta per cápita…)
7. Mapa topográfico: Es aquel en el que además de estar dibujadas las posiciones relativas de los objetos está representado el desnivel en altura. Estos desniveles se representan dibujando unas líneas llamadas curvas de nivel o isohipsas. Su escala es de 1:50.000, aunque posteriormente se comenzaron a realizar mapas de escala 1:25.000. Actualmente existe una versión digitalizada.
8. Meridiano: Línea imaginaria semicircular que va de polo a polo. Junto a los paralelos constituyen la red geográfica que permite la localización de los fenómenos geográficos en la Tierra. Los meridianos, además, se emplean para calcular la longitud y distribuir las zonas horarias. El meridiano principal o meridiano 0º pasa por el observatorio inglés de Greenwich y divide la tierra en dos hemisferios: occidental y oriental. La Península se extiende por ambos hemisferios al ser atravesada por el meridiano 0º. Atraviesa el macizo del Monte Perdido y las localidades de Villanueva de Sigena (Huesca), Castellón de la Plana, Denia y Altea (Alicante).
9. Meridional: Posición sur respecto a un punto de referencia.
10. Occidental: Posición oeste respecto a un punto de referencia.
11. Ordenación del territorio: Gestión de los procesos de planificación y desarrollo de los espacios geográficos, orientada a reducir los desequilibrios en el reparto de la población, de la riqueza y otros aspectos. Además propicia su desarrollo sostenible.
12. Oriental: Posición este respecto a un punto de referencia.
13. Paisaje geográfico: El aspecto que adquiere un lugar o espacio de la tierra como resultado de las interrelaciones de fenómenos físicos, biológicos y humanos que allí se producen. Una clasificación básica es su división paisaje en natural y paisaje humanizado.
14. Paralelo: Es un círculo imaginario perpendicular al eje terrestre. Junto a los meridianos constituyen la red geográfica que permite la localización de los fenómenos geográficos en la Tierra. Los paralelos, además, se emplean para calcular la latitud y la inclinación de los rayos solares. El principal o paralelo 0º es el ecuador, que divide la tierra en dos hemisferios, norte y sur. En nuestro territorio destaca el paralelo 40º N que tras cruzar Portugal, atraviesa las comunidades de Extremadura, Castilla-La Mancha, Madrid, Castilla-La Mancha otra vez, Aragón, la Comunidad Valenciana y, tras cruzar 300 kilómetros por el Mediterráneo, roza la Baleares a la altura de Menorca. Las localidades de Plasencia, Talavera de la Reina, Tarancón, Arcos de las Salinas, Castellón de la Plana (donde se cruza con el meridiano 0º) y Ciudadela se encuentran en sus inmediaciones.
15. Septentrional: Posición norte o boreal respecto a un punto de referencia.
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CONCEPTOS POR REFERENCIAS
1. En cartografía, la relación que existe entre las dimensiones de lo representado en el mapa y la realidad se denomina ESCALA.
2. Los mapas que representan las características estructurales de la distribución espacial de un fenómeno geográfico particular, se denominan MAPAS TEMÁTICOS.
3. La porción de territorio que presenta unas características morfológicas y funcionales semejantes, como resultado de la acción y la interacción de factores naturales y humanos, se denomina PAISAJE GEOGRÁFICO.
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El grabado que hemos escogido como encabezamiento se titula Provincia de Santander.— Vista de la Villa y del Puerto de Castro-Urdiales tomada desde el Mar. Se realizó a partir de un dibujo del natural de Juan Comba. Procede de La Ilustración Española y Americana publicada el veintidós de noviembre de 1889 (número XLIII, Año XXXIII).
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
Ice/Fire, Cold/Hot, Water/Fire
Yin Yang is a Chinese symbol illustrating "how polar or seemingly contrary forces are interconnected and interdependent in the natural world, and how they give rise to each other in turn." This simple shape of mirrored inverted images is represents many concepts and a variety of religious, and cultural practices including Taoism, the I Ching, Tai Chi and more. Continue reading on Wikipedia.
Yin, Yang, slow, fast, soft, hard, yielding, solid, diffuse, focused, cold, hot, wet, dry, passive, aggressive, water, fire, earth, sky, moon, sun, femininity, masculinity, nighttime, daytime.
Kālī, also known as Kālikā (Sanskrit: कालिका), is the Hindu goddess associated with empowerment, shakti. She is the fierce aspect of the goddess Durga (Parvati). The name Kali comes from kāla, which means black, time, death, lord of death: Shiva. Since Shiva is called Kāla— the eternal time — the name of Kālī, his consort, also means "Time" or "Death" (as in "time has come"). Hence, Kāli is the Goddess of Time and Change. Although sometimes presented as dark and violent, her earliest incarnation as a figure of annihilation of evil forces still has some influence. Various Shakta Hindu cosmologies, as well as Shākta Tantric beliefs, worship her as the ultimate reality or Brahman. Comparatively recent devotional movements largely conceive Kāli as a benevolent mother goddess. Kālī is represented as the consort of Lord Shiva, on whose body she is often seen standing. Shiva lies in the path of Kali, whose foot on Shiva subdues her anger.
ETYMOLOGY
Kālī is the feminine form of kālam ("black, dark coloured"). Kāla primarily means "time" but also means "black" in honor of being the first creation before light itself. Kālī means "the black one" and refers to her being the entity of "time" or "beyond time." Kāli is strongly associated with Shiva, and Shaivas derive the masculine Kāla (an epithet of Shiva) to come from her feminine name. A nineteenth-century Sanskrit dictionary, the Shabdakalpadrum, states: कालः शिवः। तस्य पत्नीति - काली। kālaḥ śivaḥ। tasya patnīti kālī - "Shiva is Kāla, thus, his consort is Kāli" referring to Devi Parvathi being a manifestation of Devi MahaKali.
Other names include Kālarātri ("black night"), as described above, and Kālikā ("relating to time"). Coburn notes that the name Kālī can be used as a proper name, or as a description of color.
Kāli's association with darkness stands in contrast to her consort, Shiva, who manifested after her in creation, and who symbolises the rest of creation after Time is created. In his supreme awareness of Maya, his body is covered by the white ashes of the cremation ground (Sanskrit: śmaśāna) where he meditates, and with which Kāli is also associated, as śmaśāna-kālī.
ORIGINS
Hugh Urban notes that although the word Kālī appears as early as the Atharva Veda, the first use of it as a proper name is in the Kathaka Grhya Sutra (19.7). Kali is the name of one of the seven tongues of Agni, the [Rigvedic] God of Fire, in the Mundaka Upanishad (2:4), but it is unlikely that this refers to the goddess. The first appearance of Kāli in her present form is in the Sauptika Parvan of the Mahabharata (10.8.64). She is called Kālarātri (literally, "black night") and appears to the Pandava soldiers in dreams, until finally she appears amidst the fighting during an attack by Drona's son Ashwatthama. She most famously appears in the sixth century Devi Mahatmyam as one of the shaktis of Mahadevi, and defeats the demon Raktabija ("Bloodseed"). The tenth-century Kalika Purana venerates Kāli as the ultimate reality.
According to David Kinsley, Kāli is first mentioned in Hinduism as a distinct goddess around 600 CE, and these texts "usually place her on the periphery of Hindu society or on the battlefield." She is often regarded as the Shakti of Shiva, and is closely associated with him in various Puranas. The Kalika Purana depicts her as the "Adi Shakti" (Fundamental Power) and "Para Prakriti" or beyond nature.
WORSHIP & MANTRA
Kali could be considered a general concept, like Durga, and is mostly worshiped in the Kali Kula sect of worship. The closest way of direct worship is Maha Kali or Bhadra Kali (Bhadra in Sanskrit means 'gentle'). Kali is worshiped as one of the 10 Mahavidya forms of Adi Parashakti (Goddess Durga) or Bhagavathy according to the region. The mantra for worship is called Devi Argala Stotram.
Sanskrit: सर्वमङ्गलमाङ्गल्ये शिवे सर्वार्थसाधिके । शरण्ये त्र्यम्बके गौरि नारायणि नमोऽस्तु ते ॥
ॐ जयंती मंगल काली भद्रकाली कपालिनी । दुर्गा क्षमा शिवा धात्री स्वाहा स्वधा नमोऽस्तुते ॥
(Sarvamaṅgalamāṅgalyē śivē sarvārthasādhikē . śaraṇyē tryambakē gauri nārāyaṇi namō'stu tē.
Oṃ jayantī mangala kālī bhadrakālī kapālinī . durgā kṣamā śivā dhātrī svāhā svadhā namō'stutē.)
TANTRA
Goddesses play an important role in the study and practice of Tantra Yoga, and are affirmed to be as central to discerning the nature of reality as are the male deities. Although Parvati is often said to be the recipient and student of Shiva's wisdom in the form of Tantras, it is Kāli who seems to dominate much of the Tantric iconography, texts, and rituals. In many sources Kāli is praised as the highest reality or greatest of all deities. The Nirvana-tantra says the gods Brahma, Vishnu, and Shiva all arise from her like bubbles in the sea, ceaselessly arising and passing away, leaving their original source unchanged. The Niruttara-tantra and the Picchila-tantra declare all of Kāli's mantras to be the greatest and the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra all proclaim Kāli vidyas (manifestations of Mahadevi, or "divinity itself"). They declare her to be an essence of her own form (svarupa) of the Mahadevi.
In the Mahanirvana-tantra, Kāli is one of the epithets for the primordial sakti, and in one passage Shiva praises her:
At the dissolution of things, it is Kāla [Time] Who will devour all, and by reason of this He is called Mahākāla [an epithet of Lord Shiva], and since Thou devourest Mahākāla Himself, it is Thou who art the Supreme Primordial Kālika. Because Thou devourest Kāla, Thou art Kāli, the original form of all things, and because Thou art the Origin of and devourest all things Thou art called the Adya [the Primordial One]. Re-assuming after Dissolution Thine own form, dark and formless, Thou alone remainest as One ineffable and inconceivable. Though having a form, yet art Thou formless; though Thyself without beginning, multiform by the power of Maya, Thou art the Beginning of all, Creatrix, Protectress, and Destructress that Thou art.
The figure of Kāli conveys death, destruction, and the consuming aspects of reality. As such, she is also a "forbidden thing", or even death itself. In the Pancatattva ritual, the sadhaka boldly seeks to confront Kali, and thereby assimilates and transforms her into a vehicle of salvation. This is clear in the work of the Karpuradi-stotra, a short praise of Kāli describing the Pancatattva ritual unto her, performed on cremation grounds. (Samahana-sadhana)
He, O Mahākāli who in the cremation-ground, naked, and with dishevelled hair, intently meditates upon Thee and recites Thy mantra, and with each recitation makes offering to Thee of a thousand Akanda flowers with seed, becomes without any effort a Lord of the earth. Oh Kāli, whoever on Tuesday at midnight, having uttered Thy mantra, makes offering even but once with devotion to Thee of a hair of his Shakti [his energy/female companion] in the cremation-ground, becomes a great poet, a Lord of the earth, and ever goes mounted upon an elephant.
The Karpuradi-stotra clearly indicates that Kāli is more than a terrible, vicious, slayer of demons who serves Durga or Shiva. Here, she is identified as the supreme mistress of the universe, associated with the five elements. In union with Lord Shiva, she creates and destroys worlds. Her appearance also takes a different turn, befitting her role as ruler of the world and object of meditation. In contrast to her terrible aspects, she takes on hints of a more benign dimension. She is described as young and beautiful, has a gentle smile, and makes gestures with her two right hands to dispel any fear and offer boons. The more positive features exposed offer the distillation of divine wrath into a goddess of salvation, who rids the sadhaka of fear. Here, Kali appears as a symbol of triumph over death.
BENGALI TRADITION
Kali is also a central figure in late medieval Bengali devotional literature, with such devotees as Ramprasad Sen (1718–75). With the exception of being associated with Parvati as Shiva's consort, Kāli is rarely pictured in Hindu legends and iconography as a motherly figure until Bengali devotions beginning in the early eighteenth century. Even in Bengāli tradition her appearance and habits change little, if at all.
The Tantric approach to Kāli is to display courage by confronting her on cremation grounds in the dead of night, despite her terrible appearance. In contrast, the Bengali devotee appropriates Kāli's teachings adopting the attitude of a child, coming to love her unreservedly. In both cases, the goal of the devotee is to become reconciled with death and to learn acceptance of the way that things are. These themes are well addressed in Rāmprasād's work. Rāmprasād comments in many of his other songs that Kāli is indifferent to his wellbeing, causes him to suffer, brings his worldly desires to nothing and his worldly goods to ruin. He also states that she does not behave like a mother should and that she ignores his pleas:
Can mercy be found in the heart of her who was born of the stone? [a reference to Kali as the daughter of Himalaya]
Were she not merciless, would she kick the breast of her lord?
Men call you merciful, but there is no trace of mercy in you, Mother.
You have cut off the heads of the children of others, and these you wear as a garland around your neck.
It matters not how much I call you "Mother, Mother." You hear me, but you will not listen.
To be a child of Kāli, Rāmprasād asserts, is to be denied of earthly delights and pleasures. Kāli is said to refrain from giving that which is expected. To the devotee, it is perhaps her very refusal to do so that enables her devotees to reflect on dimensions of themselves and of reality that go beyond the material world.
A significant portion of Bengali devotional music features Kāli as its central theme and is known as Shyama Sangeet ("Music of the Night"). Mostly sung by male vocalists, today even women have taken to this form of music. One of the finest singers of Shyāma Sāngeet is Pannalal Bhattacharya.
In Bengal, Kāli is venerated in the festival Kali Puja, the new moon day of Ashwin month which coincides with Diwali festival.
In a unique form of Kāli worship, Shantipur worships Kāli in the form of a hand painted image of the deity known as Poteshwari (meaning the deity drawn on a piece of cloth).
LEGENDS
SLAYER OF RAKTABIJA
In Kāli's most famous legend, Devi Durga (Adi Parashakti) and her assistants, the Matrikas, wound the demon Raktabija, in various ways and with a variety of weapons in an attempt to destroy him. They soon find that they have worsened the situation for with every drop of blood that is dripped from Raktabija he reproduces a clone of himself. The battlefield becomes increasingly filled with his duplicates. Durga, in need of help, summons Kāli to combat the demons. It is said, in some versions, that Goddess Durga actually assumes the form of Goddess Kāli at this time. The Devi Mahatmyam describes:
Out of the surface of her (Durga's) forehead, fierce with frown, issued suddenly Kali of terrible countenance, armed with a sword and noose. Bearing the strange khatvanga (skull-topped staff ), decorated with a garland of skulls, clad in a tiger's skin, very appalling owing to her emaciated flesh, with gaping mouth, fearful with her tongue lolling out, having deep reddish eyes, filling the regions of the sky with her roars, falling upon impetuously and slaughtering the great asuras in that army, she devoured those hordes of the foes of the devas.
Kali destroys Raktabija by sucking the blood from his body and putting the many Raktabija duplicates in her gaping mouth. Pleased with her victory, Kali then dances on the field of battle, stepping on the corpses of the slain. In the Devi Mahatmya version of this story, Kali is also described as a Matrika and as a Shakti or power of Devi. She is given the epithet Cāṃuṇḍā (Chamunda), i.e. the slayer of the demons Chanda and Munda. Chamunda is very often identified with Kali and is very much like her in appearance and habit.
DAKSHINA KALI
In her most famous pose as Daksinakali, popular legends say that Kali, becoming drunk on the blood of her victims on the battlefield, dances with destructive frenzy. She is about to destroy the whole universe when, urged by all the gods, Shiva lies in her way to stop her. In her fury, she fails to see the body of Shiva lying amongst the corpses on the battlefield and steps upon his chest. Realizing Shiva lies beneath her feet, her anger is pacified and she calms her fury. Though not included in any of the puranas, popular legends state that Kali was ashamed at the prospect of keeping her husband beneath her feet and thus stuck her tongue out in shame. The Devi-Bhagavata Purana, which goes into great depths about the goddess Kali, reveals the tongue's actual symbolism.
The characteristic icons that depict Kali are the following; unbridled matted hair, open blood shot eyes, open mouth and a drooping tongue; in her hands, she holds a Khadga (bent sword or scimitar) and a human head; she has a girdle of human hands across her waist and an enchanted Shiva lies beneath her feet. Each of these icons represent a deep philosophical epithet. The drooping out-stuck tongue represents her blood-thirst. Lord Shiva beneath her feet represents matter, as Kali is undoubtedly the primeval energy. The depiction of Kali on Shiva shows that without energy, matter lies "dead". This concept has been simplified to a folk-tale depicting a wife placing her foot on her husband and sticking her tongue out in shame. In tantric contexts, the tongue is seen to denote the element (guna) of rajas (energy and action) controlled by sattva.
If Kali steps on Shiva with her right foot and holds the sword in her left hand, she is considered to be Dakshina Kali. The Dakshina Kali Temple has important religious associations with the Jagannath Temple and it is believed that Daksinakali is the guardian of the kitchen of the Lord Jagannath Temple. Puranic tradition says that in Puri, Lord Jagannath is regarded as Daksinakalika. Goddess Dakshinakali plays an important role in the 'Niti' of Saptapuri Amavasya.
One South Indian tradition tells of a dance contest between Shiva and Kali. After defeating the two demons Sumbha and Nisumbha, Kali takes up residence in the forest of Thiruvalankadu or Thiruvalangadu. She terrorizes the surrounding area with her fierce, disruptive nature. One of Shiva's devotees becomes distracted while performing austerities, and asks Shiva to rid the forest of the destructive goddess. When Shiva arrives, Kali threatens him, claiming the territory as her own. Shiva challenges Kali to a dance contest; both of them dance and Kali matches Shiva in every step that he takes until Shiva takes the "Urdhvatandava" step, by vertically raising his right leg. Kali refuses to perform this step, which would not befit her as a woman, and became pacified.
SMASHAN KALI
If the Kali steps out with the left foot and holds the sword in her right hand, she is the terrible form of Mother, the Smashan Kali of the cremation ground. She is worshiped by tantrics, the followers of Tantra, who believe that one's spiritual discipline practiced in a smashan (cremation ground) brings success quickly. Sarda Devi, the consort of Ramakrishna Paramhansa, worshipped Smashan Kali at Dakshineshwar.
MATERNAL KALI
Another legend depicts the infant Shiva calming Kali. In this similar story, Kali has defeated her enemies on the battlefield and begun to dance out of control, drunk on the blood of the slain. To calm her down and to protect the stability of the world, Shiva is sent to the battlefield, as an infant, crying aloud. Seeing the child's distress, Kali ceases dancing to care for the helpless infant. She picks him up, kisses his head, and proceeds to breast feed the infant Shiva. This legend is notable because it shows Kali in her benevolent, maternal aspect, with which she is not usually identified.
MAHAKALI
Mahakali (Sanskrit: Mahākālī, Devanagari: महाकाली), literally translated as Great Kali, is sometimes considered as a greater form of Kali, identified with the Ultimate reality of Brahman. It can also be used as an honorific of the Goddess Kali, signifying her greatness by the prefix "Mahā-". Mahakali, in Sanskrit, is etymologically the feminized variant of Mahakala or Great Time (which is interpreted also as Death), an epithet of the God Shiva in Hinduism. Mahakali is the presiding Goddess of the first episode of the Devi Mahatmya. Here she is depicted as Devi in her universal form as Shakti. Here Devi serves as the agent who allows the cosmic order to be restored.
Kali is depicted in the Mahakali form as having ten heads, ten arms, and ten legs. Each of her ten hands is carrying a various implement which vary in different accounts, but each of these represent the power of one of the Devas or Hindu Gods and are often the identifying weapon or ritual item of a given Deva. The implication is that Mahakali subsumes and is responsible for the powers that these deities possess and this is in line with the interpretation that Mahakali is identical with Brahman. While not displaying ten heads, an "ekamukhi" or one headed image may be displayed with ten arms, signifying the same concept: the powers of the various Gods come only through Her grace.
ICONOGRAPHY
Kali is portrayed mostly in two forms: the popular four-armed form and the ten-armed Mahakali form. In both of her forms, she is described as being black in color but is most often depicted as blue in popular Indian art. Her eyes are described as red with intoxication, and in absolute rage, her hair is shown disheveled, small fangs sometimes protrude out of her mouth, and her tongue is lolling. She is often shown naked or just wearing a skirt made of human arms and a garland of human heads. She is also accompanied by serpents and a jackal while standing on a seemingly dead Shiva, usually right foot forward to symbolize the more popular Dakshinamarga or right-handed path, as opposed to the more infamous and transgressive Vamamarga or left-handed path.
In the ten-armed form of Mahakali she is depicted as shining like a blue stone. She has ten faces and ten feet and three eyes. She has ornaments decked on all her limbs. There is no association with Shiva.
The Kalika Purana describes Kali as possessing a soothing dark complexion, as perfectly beautiful, riding a lion, four-armed, holding a sword and blue lotuses, her hair unrestrained, body firm and youthful.
In spite of her seemingly terrible form, Kali Ma is often considered the kindest and most loving of all the Hindu goddesses, as she is regarded by her devotees as the Mother of the whole Universe. And because of her terrible form, she is also often seen as a great protector. When the Bengali saint Ramakrishna once asked a devotee why one would prefer to worship Mother over him, this devotee rhetorically replied, "Maharaj, when they are in trouble your devotees come running to you. But, where do you run when you are in trouble?"
According to Ramakrishna, darkness is the Ultimate Mother, or Kali:
My Mother is the principle of consciousness. She is Akhanda Satchidananda; indivisible Reality, Awareness, and Bliss. The night sky between the stars is perfectly black. The waters of the ocean depths are the same; The infinite is always mysteriously dark. This inebriating darkness is my beloved Kali.
SRI RAMAKRISHNA
This is clear in the works of such contemporary artists as Charles Wish, and Tyeb Mehta, who sometimes take great liberties with the traditional, accepted symbolism, but still demonstrate a true reverence for the Shakta sect.
POPULAR FORM
Classic depictions of Kali share several features, as follows:
Kali's most common four armed iconographic image shows each hand carrying variously a sword, a trishul (trident), a severed head and a bowl or skull-cup (kapala) catching the blood of the severed head.
Two of these hands (usually the left) are holding a sword and a severed head. The Sword signifies Divine Knowledge and the Human Head signifies human Ego which must be slain by Divine Knowledge in order to attain Moksha. The other two hands (usually the right) are in the abhaya (fearlessness) and varada (blessing) mudras, which means her initiated devotees (or anyone worshipping her with a true heart) will be saved as she will guide them here and in the hereafter.
She has a garland consisting of human heads, variously enumerated at 108 (an auspicious number in Hinduism and the number of countable beads on a Japa Mala or rosary for repetition of Mantras) or 51, which represents Varnamala or the Garland of letters of the Sanskrit alphabet, Devanagari. Hindus believe Sanskrit is a language of dynamism, and each of these letters represents a form of energy, or a form of Kali. Therefore she is generally seen as the mother of language, and all mantras.
She is often depicted naked which symbolizes her being beyond the covering of Maya since she is pure (nirguna) being-consciousness-bliss and far above prakriti. She is shown as very dark as she is brahman in its supreme unmanifest state. She has no permanent qualities - she will continue to exist even when the universe ends. It is therefore believed that the concepts of color, light, good, bad do not apply to her - she is the pure, un-manifested energy, the Adi-shakti.
SHIVA IN KALI ICONOGRAPHY
In both these images she is shown standing on the prone, inert or dead body of Shiva. There is a legend for the reason behind her standing on what appears to be Shiva's corpse, which translates as follows:
Once Kali had destroyed all the demons in battle, she began a terrific dance out of the sheer joy of victory. All the worlds or lokas began to tremble and sway under the impact of her dance. So, at the request of all the Gods, Shiva himself asked her to desist from this behavior. However, she was too intoxicated to listen. Hence, Shiva lay like a corpse among the slain demons in order to absorb the shock of the dance into himself. When Kali eventually stepped upon Shiva, she realized she was trampling and hurting her husband and bit her tongue in shame.
The story described here is a popular folk tale and not described or hinted in any of the puranas. The puranic interpretation is as follows:
Once, Parvati asks Shiva to chose the one form among her 10 forms which he likes most. To her surprise, Shiva reveals that he is most comfortable with her Kali form, in which she is bereft of her jewellery, her human-form, her clothes, her emotions and where she is only raw, chaotic energy, where she is as terrible as time itself and even greater than time. As Parvati takes the form of Kali, Shiva lies at her feet and requests her to place her foot on his chest, upon his heart. Once in this form, Shiva requests her to have this place, below her feet in her iconic image which would be worshiped throughout.
This idea has been explored in the Devi-Bhagavata Purana and is most popular in the Shyama Sangeet, devotional songs to Kali from the 12th to 15th centuries.
The Tantric interpretation of Kali standing on top of her husband is as follows:
The Shiv tattava (Divine Consciousness as Shiva) is inactive, while the Shakti tattava (Divine Energy as Kali) is active. Shiva and Kali represent Brahman, the Absolute pure consciousness which is beyond all names, forms and activities. Kali, on the other hand, represents the potential (and manifested) energy responsible for all names, forms and activities. She is his Shakti, or creative power, and is seen as the substance behind the entire content of all consciousness. She can never exist apart from Shiva or act independently of him, just as Shiva remains a mere corpse without Kali i.e., Shakti, all the matter/energy of the universe, is not distinct from Shiva, or Brahman, but is rather the dynamic power of Brahman. Hence, Kali is Para Brahman in the feminine and dynamic aspect while Shiva is the male aspect and static. She stands as the absolute basis for all life, energy and beneath her feet lies, Shiva, a metaphor for mass, which cannot retain its form without energy.
While this is an advanced concept in monistic Shaktism, it also agrees with the Nondual Trika philosophy of Kashmir, popularly known as Kashmir Shaivism and associated most famously with Abhinavagupta. There is a colloquial saying that "Shiva without Shakti is Shava" which means that without the power of action (Shakti) that is Mahakali (represented as the short "i" in Devanagari) Shiva (or consciousness itself) is inactive; Shava means corpse in Sanskrit and the play on words is that all Sanskrit consonants are assumed to be followed by a short letter "a" unless otherwise noted. The short letter "i" represents the female power or Shakti that activates Creation. This is often the explanation for why She is standing on Shiva, who is either Her husband and complement in Shaktism or the Supreme Godhead in Shaivism.
To properly understand this complex Tantric symbolism it is important to remember that the meaning behind Shiva and Kali does not stray from the non-dualistic parlance of Shankara or the Upanisads. According to both the Mahanirvana and Kularnava Tantras, there are two distinct ways of perceiving the same absolute reality. The first is a transcendental plane which is often described as static, yet infinite. It is here that there is no matter, there is no universe and only consciousness exists. This form of reality is known as Shiva, the absolute Sat-Chit-Ananda - existence, knowledge and bliss. The second is an active plane, an immanent plane, the plane of matter, of Maya, i.e., where the illusion of space-time and the appearance of an actual universe does exist. This form of reality is known as Kali or Shakti, and (in its entirety) is still specified as the same Absolute Sat-Chit-Ananda. It is here in this second plane that the universe (as we commonly know it) is experienced and is described by the Tantric seer as the play of Shakti, or God as Mother Kali.
From a Tantric perspective, when one meditates on reality at rest, as absolute pure consciousness (without the activities of creation, preservation or dissolution) one refers to this as Shiva or Brahman. When one meditates on reality as dynamic and creative, as the Absolute content of pure consciousness (with all the activities of creation, preservation or dissolution) one refers to it as Kali or Shakti. However, in either case the yogini or yogi is interested in one and the same reality - the only difference being in name and fluctuating aspects of appearance. It is this which is generally accepted as the meaning of Kali standing on the chest of Shiva.
Although there is often controversy surrounding the images of divine copulation, the general consensus is benign and free from any carnal impurities in its substance. In Tantra the human body is a symbol for the microcosm of the universe; therefore sexual process is responsible for the creation of the world. Although theoretically Shiva and Kali (or Shakti) are inseparable, like fire and its power to burn, in the case of creation they are often seen as having separate roles. With Shiva as male and Kali as female it is only by their union that creation may transpire. This reminds us of the prakrti and purusa doctrine of Samkhya wherein prakāśa- vimarśa has no practical value, just as without prakrti, purusa is quite inactive. This (once again) stresses the interdependencies of Shiva and Shakti and the vitality of their union.
Gopi Krishna proposed that Kali standing on the dead Shiva or Shava (Sanskrit for dead body) symbolised the helplessness of a person undergoing the changing process (psychologically and physiologically) in the body conducted by the Kundalini Shakti.
DEVELOPMENT
In the later traditions, Kali has become inextricably linked with Shiva. The unleashed form of Kali often becomes wild and uncontrollable, and only Shiva is able to tame her just as only Kali can tame Shiva. This is both because she is often a transformed version of one of his consorts and because he is able to match her wildness.
The ancient text of Kali Kautuvam describes her competition with Shiva in dance, from which the sacred 108 Karanas appeared. Shiva won the competition by acting the urdva tandava, one of the Karanas, by raising his feet to his head. Other texts describe Shiva appearing as a crying infant and appealing to her maternal instincts. While Shiva is said to be able to tame her, the iconography often presents her dancing on his fallen body, and there are accounts of the two of them dancing together, and driving each other to such wildness that the world comes close to unravelling.
Shiva's involvement with Tantra and Kali's dark nature have led to her becoming an important Tantric figure. To the Tantric worshippers, it was essential to face her Curse, the terror of death, as willingly as they accepted Blessings from her beautiful, nurturing, maternal aspect. For them, wisdom meant learning that no coin has only one side: as death cannot exist without life, so life cannot exist without death. Kali's role sometimes grew beyond that of a chaos - which could be confronted - to that of one who could bring wisdom, and she is given great metaphysical significance by some Tantric texts. The Nirvāna-tantra clearly presents her uncontrolled nature as the Ultimate Reality, claiming that the trimurti of Brahma, Vishnu and Rudra arise and disappear from her like bubbles from the sea. Although this is an extreme case, the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra declare her the svarupa (own-being) of the Mahadevi (the great Goddess, who is in this case seen as the combination of all devis).
The final stage of development is the worshipping of Kali as the Great Mother, devoid of her usual violence. This practice is a break from the more traditional depictions. The pioneers of this tradition are the 18th century Shakta poets such as Ramprasad Sen, who show an awareness of Kali's ambivalent nature. Ramakrishna, the 19th century Bengali saint, was also a great devotee of Kali; the western popularity of whom may have contributed to the more modern, equivocal interpretations of this Goddess. Rachel McDermott's work, however, suggests that for the common, modern worshipper, Kali is not seen as fearful, and only those educated in old traditions see her as having a wrathful component. Some credit to the development of Devi must also be given to Samkhya. Commonly referred to as the Devi of delusion, Mahamaya or Durga, acting in the confines of (but not being bound by) the nature of the three gunas, takes three forms: Maha-Kali, Maha-Lakshmi and Maha-Saraswati, being her tamas-ika, rajas-ika and sattva-ika forms. In this sense, Kali is simply part of a larger whole.
Like Sir John Woodroffe and Georg Feuerstein, many Tantric scholars (as well as sincere practitioners) agree that, no matter how propitious or appalling you describe them, Shiva and Devi are simply recognizable symbols for everyday, abstract (yet tangible) concepts such as perception, knowledge, space-time, causation and the process of liberating oneself from the confines of such things. Shiva, symbolizing pure, absolute consciousness, and Devi, symbolizing the entire content of that consciousness, are ultimately one and the same - totality incarnate, a micro-macro-cosmic amalgamation of all subjects, all objects and all phenomenal relations between the "two." Like man and woman who both share many common, human traits yet at the same time they are still different and, therefore, may also be seen as complementary.
Worshippers prescribe various benign and horrific qualities to Devi simply out of practicality. They do this so they may have a variety of symbols to choose from, symbols which they can identify and relate with from the perspective of their own, ever-changing time, place and personal level of unfolding. Just like modern chemists or physicists use a variety of molecular and atomic models to describe what is unperceivable through rudimentary, sensory input, the scientists of ontology and epistemology must do the same. One of the underlying distinctions of Tantra, in comparison to other religions, is that it allows the devotee the liberty to choose from a vast array of complementary symbols and rhetoric which suit one's evolving needs and tastes. From an aesthetic standpoint, nothing is interdict and nothing is orthodox. In this sense, the projection of some of Devi's more gentle qualities onto Kali is not sacrilege and the development of Kali really lies in the practitioner, not the murthi.
A TIME magazine article of October 27, 1947, used Kali as a symbol and metaphor for the human suffering in British India during its partition that year.
Swami Vivekananda wrote his favorite poem Kali the Mother in 1898.
IN NEW AGE & NEOPAGANISM
An academic study of Western Kali enthusiasts noted that, "as shown in the histories of all cross-cultural religious transplants, Kali devotionalism in the West must take on its own indigenous forms if it is to adapt to its new environment." The adoption of Kali by the West has raised accusations of cultural appropriation:
A variety of writers and thinkers have found Kali an exciting figure for reflection and exploration, notably feminists and participants in New Age spirituality who are attracted to goddess worship. Kali is a symbol of wholeness and healing, associated especially with repressed female power and sexuality. [However, such interpretations often exhibit] confusion and misrepresentation, stemming from a lack of knowledge of Hindu history among these authors, draw upon materials written by scholars of the Hindu religious tradition. The majority instead rely chiefly on other popular feminist sources, almost none of which base their interpretations on a close reading of Kali's Indian background. The most important issue arising from this discussion - even more important than the question of 'correct' interpretation - concerns the adoption of other people's religious symbols. It is hard to import the worship of a goddess from another culture: religious associations and connotations have to be learned, imagined or intuited when the deep symbolic meanings embedded in the native culture are not available.
WIKIPEDIA
A mandala map of the Shingon Buddhist Mantra School's cosmology.
There are three universal truths found in Shingon Buddhism, the universal essence, universal form, and universal function.
The universal essence is in regard to the chakra body, otherwise known as the wheel body. The chakra body is a circle composed of elemental circles which encompass the nature of all phenomena including the dharma, the law of universal norms, Buddhist teachings, karmic consequences, thought and all things. There are three Buddha bodies or three chakra bodies for three types of listeners. The first chakra body exists in its own nature, this body manifests in the form of Buddhas who read the innate original nature by meditation. The second is the right dharma chakra body which connects the Bodhisattva to those who search for liberation by right dharma. The third is the doctrine command chakra body which exists in wrathful forms that must command those difficult to convert. Each chakra body is made up five chakras into a Stupa which creates the Matrix world.
The first chakra is the earth chakra found just below the naval and represented by the yellow square. This is the root chakra which roots the lower body into the `yoga throne of indestructible diamond` This is the throne of Indra which casts light brilliantly onto all beings cultivating Ji. This chakra acts as support and ultimately resembles the uncreated. The mantra for this chakra is Namah a
The second chakra is the water chakra found at the naval which changes into the white circle. The water chakra, also known as the lotus throne, radiates like a clear moon and irrigates all things with the water of great compassion, nourishing all in Samadhi. This chakra acts as an agent of quickening and ultimately resembles ineffableness. The mantra for this chakra is Namah VA
The third chakra is the fire chakra found at the heart which changes into a red pyramid. This chakra shines like the red rising sun and emits a fire of knowledge to burn all defilements. This is a seal of the dharma world which acts as maturation and ultimately resembles a freedom of defilement. The mantra for this chakra is Namah ram
The fourth chakra is the air chakra found in between the eyes which changes into a black half moon. This chakra exercises the power of freedom and exorcises maleficent and demonic influences. This is the seal of turning the wheel functioning as growth and ultimately meaning freedom from causality. The mantra for this chakra is Namah ham
The fifth chakra is the space chakra found at the top of the head which changes to a blue jewel. This chakra is the great space, the great void and seal of the great wisdom sword. This chakra acts as all pervasive and ultimately resembles the attributes of space. The mantra for this chakra is Namah kham
The sixth Chakra is the consciousness existing above and beyond the head which changes to white or all colours. This is the chakra of perception and determination, formless in nature. This chakra is ungraspable and ultimately void. The first five physical chakras pervade the sixth and yet the sixth pervades all five. The mantra for this chakra is Namah Hum
These chakras are made of the primary colours including white, which is all colours, and black which is void of colour. All together these chakras colour and shade all things. These are the six eternal, omnipresent and indestructible elements which are irreducible components of all three dharma bodies, that of desire, form, and formless worlds.
The universal form is in regard to four Mandalas. The all pervading oneness which Shingon calls Mahaivairocana is the dharma body fused with form in the conditioned cosmos, equivalent to the virtues of one of the Buddhist faith. This dharma body is Mandala, the form of all encompassing and complete circle. The first of the four mandalas is the great mandala. This is the universe of form composed of the six elements and colours made up of images. The second mandala is the Samaya mandala which is the universe of symbolic form which identifies the Buddha’s powers and the bodhisattva’s vows through symbols such as the vajra, sword, jewels and such. The Samaya mandala is activated with the coming together of hand gestures called mudras. The third mandala is the dharma mandala which contains all sounds of the universe and identifies with the original vow. All sounds are resembled by their Sanskrit seed sound, the seed which flowers into all words. The fourth mandala is the action mandala which is composed of all actions and is uncoloured where as form is forgotten and form is seeing. In the center of the four mandalas is the great radiating light of the sun, of Mahiavairocana, all the mandalas existing as attributes of Mahaivairocana. The four mandalas within the being interpenetrate each other without hindrance uniting body and mind with Buddha body and mind in a universal form of suchness.
The Buddha said `Mandala is what gives birth to all Buddhas, incomparable excellent flavor` Firstly, the mandala means circle, wheel, or chakra, a totality of the whole, completeness. Totality is formed by its parts, like a wheel is formed of a hub, spokes and empty space. A circle is an assembly, such as a circle of friends, or bodhisattvas. Secondly what gives birth to all Buddha`s and awakens the Buddha nature within? In Buddhism this is the seed, the bodhicitta. The citta is planted in the earth of the mind of all knowledge, than moistened by the water of great compassion, warmed by the sun of great wisdom, animated by air of great method and obstructed in space of great void, the citta develops into the dharma world as a sprout of inconceivable dharma nature. Thirdly the most excellent flavor is that in referring to the dharma world as a sea of milk, oceans of unformed chaos with unobstructed potentiality. Churned, the milk solidifies and the most refined, the most pure part rises to the surface. Condensing, unchanging, firm, without residue, we find a concentration of the dharma.
Mandala is a circle, birth to Buddha and concentration. A mandala is a circle of ritual enclosure contained within is a field free of distractions. Mandala is a platform for awakening a place of the way. Way or `do` is synonymous with awakening, a dojo is a place of the way, of awakening. Mandala is a map of the cosmos, a representational domain for self realization through the purifying of karmas. The domain is entered or `yoked` to through universal functioning of the three mysteries.
The universal function is the truth of the three interpenetrating mysteries. Actions of men are of three types which are physical actions of the body, speech and functions of the mind. These three functions are adorned as mysteries because unless awakened are truly inconceivable.
The first mystery is the mystery of the body which is activated through hand gestures called mudras. These mudras are bodily interpenetration with phenomenon and the Dharma body which consists of five bodies. These being the precept body a perfection of precepts beyond moral conditioning, the meditation body free from illusion, The wisdom body of prajna and perfected knowledge, the liberation body of unconditioned nirvana and the knowledge of liberation where clear perception abides in liberation. The left hand resembles these five dharma bodies where as the right hand resembles the five elements. The performer of these gestures is really affirming a vow and performing a seal of faith.
The second mystery is the mystery of speech which is activated through invocations called mantras or dharanis. Dharani is a verbal formula to invoke Buddha, a calling for oneness. Dharani is a support which sustains. Mantra stems from the Sanskrit seeds of `man` which means thought and `tra` which means liberates or container. Thus mantra means container of thought. This is the container for the essence of doctrine and the Dharma bodies. One syllable can contain all dharmas beyond which conceptualizing, illusory words are able to convey the dharmas unconditioned suchness beyond causality and the limitations of space and time. Although Mantras contain powers capable of miracles, the true aim is that of liberation.
The third mystery is the mystery of the mind activated through visualizations. The mind lies in a formless void, and it is important to note here that Esotericism does not aim at the void but to interpenetrate form. Visualization manifests through a one pointed concentration that brings the image into the mind-heart within the chakra body which forms a seal of entry. The mind`s eye sees that true form is emptiness. There is no grasping here, no differentiating the illusory of the symbol or to see real by cutting the unreal but to just see things as they are in their non-duality.
The external formal mandala is not the true mandala but a meditational support consisting of externalized rites for a realization of an internal yoke to the true mandala. To realize this inner mandala satisfies all desires. Mandala abides in the mind and knowing this one can receive full fruition of the Bodhi-citta tree and recognize god`s eye view. Mandala does not differ from consciousness nor consciousness differs from mandala, they are identical. The outward painted mandala is both a schema of Dharma world made up phenomenal dharmas and a schema, the underlying organizational framework, of the mind of being. The mandala is an energy grid that represents the constant flow of the divine and demonic, the human and animal. These are impulses that interact in constructive or deconstructive patterns that are a mesocosm consisting of the macrocosm with the microcosm, the mundane with sublime. The Mandala purges the body of demons and embodies the divine through the cleansing of the elements. Mandala is a template for the divine. The energy flows into the center of the mandala, rather implodes to the source which is a reversal of the original cosmology. The energy flows through channels (nadis) into energy centers composed of concentric circles (chakras) to reach unity with the `godhead`. The mandala wholly contained within mind interpenetrates all phenomena.
The Buddhist Cosmology
The Buddhist Cosmos is instructionally approached in my mandala from the sides with visual guides for the mantras and mudras to be used in approaching the center to stimulate the three mysteries and seal one into the mandala. Following the chakra bodies is the mudra for the golden turtle which arises out of the sea of samsara. The golden turtle is untarnished and is free to roam between nirvana and samsara as earth and water. On top of the golden turtle is the jewel palace of Mt. Sumeru, the immoveable resides here. Following these embodiments one is to hold their hands in J-Yin and chant the seed syllables of the elements `Ah Vi Ra Hum Kham` and embody Mahavairocana, the body of all form. Earth supports one where water is necessary in welfare as fire is to burn away false assumptions and delusions while the air blows away the dust of passions and space remains non-discriminating without distinctions. This Dharani destroys hindrances. Ah enters Nirvana through cessation, Vi is the bondless Samadhi, Ra is the dust of defilements wiped away, Ha+U+M is the three liberation gates which severe distinctions of formlessness and finally Kham which is space and void, the negation of negation and void of void, Buddha hood. This is the stupa of the body and when perfected all bad karma vanishes.
Following the chakra chain is the Heaven realms. This begins with the six heavens of the world of desire. The first heaven exists on earth which consists of the four kings of the directions, protector, wide-eyed, renowned and virtuous. Following the first heaven is the last earthly heaven which is on the summit of Mt. Sumeru in Indra`s palace located in the center of heaven. The third heaven exists in the realm of the sky and is the heaven of `Yama` or time. This is the heaven of the king of the world of the dead where the season is always good and inhabitants enjoy occasional pleasures. The next heaven is the heaven of commitment where inhabitants are content with their pleasures. This is the pureland of Miroku, the future Buddha, and the realm where bodhisattvas dwell before born on earth. The fifth heaven is the joy in transformations where inhabitants enjoy pleasures which the create themselves. The sixth heaven is the free enjoyment of transformation and pleasure created by others. King Mara the tempter reins in this heaven.
Following the heavens of the world of desire are the heavens of the world of form which consists of heavens belonging to four meditations. All forms of existence until now constitute the world of desire and now inhabitants are free of passion and desire. The heavens of the first meditation have transcended smell and taste but are still hindered in meditation, however not of sexual desire. There are five mental functions in this heaven which are investigation, reflection, joy, bliss and Samadhi. This is the abode of Brahma where one believes not to be bound of causation and can transform heaven and earth at will. There are no Buddhist inhabitants in this Hindu realm. The Heavens of the second meditation have transcended the five senses and types of consciousness. Thought, joy, and renunciation are all that remain. There is no pleasure or pain and attraction. True identity is recognized. The heavens of the third meditation are like the second but contain only one thought. The heavens of the fourth meditation are cloudless in that they need no support. There is an auspicious birth as the result of an abundance of merit. Here exists the heaven without thought that is without mental, perceptive and feeling functions, a warm resemblance of death. This is a heaven without Buddhist inhabitants for non returners, although they have not escaped the wheel of being. The non-returner has reached three fourths of the level of attainment. That is they have first entered the stream by turning against the stream of samsara. Secondly is the once-returner who has one more birth on earth to attain nirvana and the non-returner does not return to the desire realms of false practices and views. Finally one may become an Arhat to be unborn and escape rebirth.
Following the heavens of the world of form are the heavens of the formless world. These heavens are without form, beyond spatiality and subjection to causality. There are no longer the five physical aggregates but only aggregates of the mind/function. These again are perception, connotation, volition and consciousness. This is an ecstatic state of pure spiritual existence consisting of four meditations of the void. The first is infinite space in which the mind severed of form. Next is infinite consciousness which severs the mind of infinite space into infinite consciousness. Next we find non-existence which severs the mind of infinite consciousness to not exist. Finally we reach neither thought nor non-thought which severs the mind from thought contained in consciousness and non-thought of non-existence. Beyond this is the unconditioned immutable eternal world of the Buddhas.
Following the heavens are the ten stations of Buddha hood which are not hierarchical but horizontal identities, that is virtues that occur instantaneously upon attaining the realization of Buddha mind. The first station is of the dharma cloud, the perfection of the paramita of knowledge, whence wisdom and compassion has been perfected the bodhisattvas virtue permeates like a cloud and rains the elixir of Dharma to nourish and irrigate all sentient beings. The second is the station of wisdom of skills is where the paramita of power is perfected, powers and eloquence have been mastered which gives freedom to aid all beings with versatility of powers being paramitas, vows, supernatural faculties, mind, faith, compassion, love, dharanis and such things of suchness. The third station is of immovability, the perfection of the paramita of vows which is immutable in wisdom, immoveable in formless and fulfills the liberation of all beings. The third station is overcoming the supremely difficult, that is the perfection of the paramita of patience, the non-duality of mundane and absolute. The fourth station is of being face to face with wisdom, the paramita of wisdom consists of the immediate presence of wisdom, that is perceives absolute identity with the eyes. The fifth station is overcoming the supremely difficult, that is the perfection of the paramita of patience, the non-duality of mundane and absolute. The sixth station is that of blazing wisdom, the paramita of exertion where knowledge burns brilliantly and burns away illusion. The seventh station is that of manifesting light, the paramita of patience where the delusions of practice has been cut and one has the patience to understand. The eighth station is the freedom from defilements and union of body-mind which is the paramita of precepts where the delusion of practice is cut by removing improper action from beginningless time. The ninth station is the station of joy, the giving paramita which is the single thought of non discriminating knowledge. The tenth station is of far-reaching practice, the perfection to the paramita of method, this is a great compassion which is entirely selfless and consists of spiritual aims toward all sentient beings.
Descending from the center is the realm of man and the eight disasters which befall him. These consist of a world of secular views, deformed senses, remote places, the heavens of long life without thought, and of the world of mappo where no Buddha appears. The last three disasters are hungry ghosts, animals and hells which will soon be covered. Next is the realm of the Asuras which are figures of Hindu mythology that are `without wine or beauty` and are false gods seeing in Buddhism as belligerent beings whom make war on Indra and when they gain supremacy in this endless battle evil and chaos prevail. Following this is the realm of animals consisting of living creatures such as the birds, bees, beasts, dragons, shells and insects that are all suffering of mutual slaughter. This is the realm of the blind sheepman whom are spiritually blind and trapped in samsara by illusion.
The realm of the hungry ghosts consists of three classes of ghosts, each with three subclasses. The first class is ghosts with no possessions which consist of torch mouthed ghosts, needle thin throat ghosts and ghosts with foul breath. The Second class is ghosts with few possessions which consist of needle-haired ghosts, ghosts with rank hair and ghosts with large ulcers. The third class is ghosts with many possessions consisting of ghosts who receive discards and live on food after being used in offerings, ghosts who receive lost food that is left wayside by travelers and powerful ghosts.
There are than single isolated hells in mountains and deserts and neighboring hells which are smaller progressive hells which lay in close proximity to each hell. I have added a hell to the Shingon cosmology and that is the suicidal hell, this realm where one selfishly throws away their gift of life. There are also radical hells which consist of eight cold and eight hot hells.
The cold hells cause inhabitants to suffer by degrees of coldness. The arbuda hell is so cold that it causes blisters. The nirarbuda hell is even colder causing blisters to burst. Atata is the hell of chattering teeth. Hahaua is the hell and sound made by sufferers. Huhuua is the hell and sound of the breath of sufferers. The blue lotus hell is so cold that it causes patches on the skin to look like blue lotus. The red lotus hell is even colder and causes patches of red lotus on the skin. The great red lotus hell consists of the skin being entirely covered by red lotus.
The hot hells cause suffering to inhabitants in karmic retribution. The rebirth hell contains inhabitants who are repeatedly put to death and immediately brought back by a cold wind, renewed to torture. The hell of black ropes has sufferers bound with ropes and chopped to pieces. The hell of multitudinous combinations consists of combinations of instruments used to torture. The wailing hell`s inhabitants wail in anguish. The great wailing hell`s inhabitants wail in great suffering. The hell of scorching heat is self explanatory. Finally there is the hell of non-intervals which is for the worst of the five deadly offences that are patricide, matricide, killing an Arhat, doing injury to the body of a Buddha or cause disunity in the Sangha. There is no interval of suffering in between death and rebirth here, no interval in hell, in life. There is no part of body-mind that does not suffer.
Ascending from the center is the three stages of awakening which is permeated by the three mysteries. These stages are the three kalpas which are false tenets to be destroyed. These objective cuttings of false tenets consist of stages of fearlessness which relate to subjective attainment of mental tranquility. These stages of fearlessness are states of rest that are free of anxiety and suffering which escapes turning the karmic wheel. These are not just `absences` of fear but total regeneration of being which directly correspond to the ten stages of mind. The ascension of these stages of mind is a centrifugal expansion that is outward flowing from the center to periphery which is then followed by a centripetal return back to the center.
The first kalpa is the delusion to the nature of man, that there is permanent individuality and that the ego is real and not a temporary composition of the five aggregates which are form, perception, conception, volition, and consciousness. This kalpa is removed by meditating on the voidness of aggregates as well as the twelve linked chain of dependent co-origination which gives rise to birth and suffering. The links of the chain are ignorance (the cause of all illusion), actions produced by ignorance, consciousness which arises in the womb, name and form, the six sense organs, contact, perception/ sensation, desire, the attachment of grasping, existence, birth and death.
There are four fearlessnesses which belong to the first Kalpa. The first fearlessness is the fearlessness of virtue which is the result of good karma in previous lives. This fearlessness takes refuge in the three jewels which are the Buddha, Dharma and Sangha. One who has attained this level of fearlessness has turned from the worldly life by taking the five precepts which are to not kill, steal, be promiscuous, use immoderate language and abuse intoxicants. Thus one has removed fear of three paths being the hells, ghosts and animals. This commences the first practices of the three mysteries and awakens the bodhicitta. This stage of fearlessness consists of the first three stages of mind. The first stage is the mind of sheep life and profane which consists of an endless cycle of rebirths for those lacking spiritual awareness. Those at this level of mind are uncontrolled and entrapped in illusion. They work on the animal level and are trapped in a fight or flight response. The second level of mind is of the foolish child who abstains. Those at this level of mind are ignorant and naïve but ethical. They live a profane life and do not hurt man. The third level of mind is of the fearlessness of a baby where one has faith in the gods and rebirth but the ego is still attached and one remains a worldly being.
The Second fearlessness belonging to the first Kalpa is the fearlessness of body. One meditates on their body and realizing impurity thus eliminates desire and greed. Those at this level of fearlessness experience heat, forms of Samadhi and honzen`s wondrous form body. The fourth stage of mind resides at this level of fearlessness which is the mind that understands an atman and the five aggregates. This is the first Buddhist stage of mind where all being are recognized as a temporary link or flux of the aggregates.
The third level of fearlessness belonging to the first kalpa is that of the non self. This is the recognition that the body-mind is composed temporarily of the five aggregates and thus lacks any true existence and permanent self. This severs attachments and cools the mind in union or yoga with honzen that cuts desire and pride which leads to tranquility. The fourth level of fearlessness belonging to the first kalpa is fearlessness of the Dharmas. Having realized the non-existing self one severs Dharma attachments by analyzing them and seeing that they too are composed of five aggregates and arise by co-dependent origination without self nature. One at this level of fearlessness knows the twelve link chain and meditates on the ten illusions arising of environmental conditions. These illusions consist of sleight of hand, mirage, dreams, reflections and shadows, echoes, moon reflected on water, floating bubbles, dust, and fire wheels. The stage of mind corresponding to these two levels of fearlessness is the fifth level where the seeds of karma have been eradicated and the truth of the twelve linked chain is realized but cannot be taught.
The second Kalpa is to eradicate the false tenet that dharmas have a true and permanent nature that underlies the five aggregates. This kalpa removes the duality and therefore existence of nirvana and samsara. Forms in yogic practices are realized to be merely illusory forms arising in the mind and that not a single dharma exists outside of mind.
Belonging to the second Kalpa is the fifth level of fearlessness, that of the non-self of the dharmas. Having meditated on essential voidness all dharmas are realized to be formed by the linking of the five aggregates and thus exist in the store-consciousness. Essentially void, nothing exists outside of mind; there is no dichotomy between subject and object. Through this subtle union all things are undifferentiated in their self-nature.
Two levels of mind belong to the fifth fearlessness of the second kalpa. The sixth stage of mind seeks the welfare of others as a bodhisattva of the Mahayana branch of Buddhism. All dharmas and the three worlds are known in the storehouse. The seventh stage of mind has awakened to the truth that the mind is unborn. Prior to now objects had been voided and now the mind is voided as unconditional and timeless. This is achieved through eight negations being non… birth, extinction, cessation, permanence, uniformity, diversity, coming and going. The removal of these erroneous views equates in the right view.
The final Kalpa is to discard the false tenet that dharmas are separate and that subject and object are different. Identity and suchness is revealed. All dharmas are in the one true middle way. The stage of fearlessness associated to this kalpa is the fearlessness of the identity of the self-nature of all dharmas. 10,000 dharmas are suchness and suchness is the 10,000 dharmas. Prior the non-duality of dharmas, mind and voidness (sunyata) has been realized. Now voidness is itself void, the self nature of dharma is without nature and one discovers the reality of the phenomenal. Nothing can have context and therefore the self is nullified by nullifying the ground it has to stand on.
The final three stages of mind belong to this final level of fearlessness of the third Kalpa. The eighth stage of mind is of the one-way of non-action and suchness. The voidness of mind is…void. All dharmas and all thought are contained in one thought. The three truths of voidness, provisional existence and middle existence are realized. The truth of `middle existence` is the middle way of the first two truths. All dharmas are co-dependent and thus temporary causal relation and void, yet experienced and not denied which equates in provisional existence. Dharmas and existence are on the same two-sided coin as voidness. Reality is thus the middle way of the non duality of existence and voidness and forms are known to be nothing but manifestations of suchness. The ninth stage of mind realizes the absence of self-nature and full reality as is without the distinctions of phenomenon and real. This can best be described as the interdependent nature of Indra`s net of phenomenal and real where each thing is in the universe and the universe is in each thing. The tenth stage of mind is adorned by mysteries. This is the unobstructed view of all reality. Whereas the ninth stage is the expression of identity the tenth puts this in practice through body, mind and speech becoming Buddha.
A final important thing to note is that although all dharmas are ephemeral and changing they are real just as they are. The phenomenal and the void are equally real and codependent. This being said these symbols are and are not what they signify. Though they signify emptiness they are in fact empty. The signified and signifier are both dual and non-dual. The emphasis is form, not minor or universal but all forms inner-reflecting the interdependent nature of reality which is not to be seeing as an illusion but real as is. The body of the Buddha is all things and the body of all beings is Buddha.
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
Although a great many fossil fishes have been found and described, they represent a tiny portion of the long and complex evolution of fishes, and knowledge of fish evolution remains relatively fragmentary. In the classification presented in this article, fishlike vertebrates are divided into seven categories, the members of each having a different basic structural organization and different physical and physiological adaptations for the problems presented by the environment. The broad basic pattern has been one of successive replacement of older groups by newer, better-adapted groups. One or a few members of a group evolved a basically more efficient means of feeding, breathing, or swimming or several better ways of living. These better-adapted groups then forced the extinction of members of the older group with which they competed for available food, breeding places, or other necessities of life. As the new fishes became well established, some of them evolved further and adapted to other habitats, where they continued to replace members of the old group already there. The process was repeated until all or almost all members of the old group in a variety of habitats had been replaced by members of the newer evolutionary line.
The earliest vertebrate fossils of certain relationships are fragments of dermal armour of jawless fishes (superclass Agnatha, order Heterostraci) from the Upper Ordovician Period in North America, about 450 million years in age. Early Ordovician toothlike fragments from the former Soviet Union are less certainly remains of agnathans. It is uncertain whether the North American jawless fishes inhabited shallow coastal marine waters, where their remains became fossilized, or were freshwater vertebrates washed into coastal deposits by stream action.
Jawless fishes probably arose from ancient, small, soft-bodied filter-feeding organisms much like and probably also ancestral to the modern sand-dwelling filter feeders, the Cephalochordata (Amphioxus and its relatives). The body in the ancestral animals was probably stiffened by a notochord. Although a vertebrate origin in fresh water is much debated by paleontologists, it is possible that mobility of the body and protection provided by dermal armour arose in response to streamflow in the freshwater environment and to the need to escape from and resist the clawed invertebrate eurypterids that lived in the same waters. Because of the marine distribution of the surviving primitive chordates, however, many paleontologists doubt that the vertebrates arose in fresh water.
Heterostracan remains are next found in what appear to be delta deposits in two North American localities of Silurian age. By the close of the Silurian, about 416 million years ago, European heterostracan remains are found in what appear to be delta or coastal deposits. In the Late Silurian of the Baltic area, lagoon or freshwater deposits yield jawless fishes of the order Osteostraci. Somewhat later in the Silurian from the same region, layers contain fragments of jawed acanthodians, the earliest group of jawed vertebrates, and of jawless fishes. These layers lie between marine beds but appear to be washed out from fresh waters of a coastal region.
It is evident, therefore, that by the end of the Silurian both jawed and jawless vertebrates were well established and already must have had a long history of development. Yet paleontologists have remains only of specialized forms that cannot have been the ancestors of the placoderms and bony fishes that appear in the next period, the Devonian. No fossils are known of the more primitive ancestors of the agnathans and acanthodians. The extensive marine beds of the Silurian and those of the Ordovician are essentially void of vertebrate history. It is believed that the ancestors of fishlike vertebrates evolved in upland fresh waters, where whatever few and relatively small fossil beds were made probably have been long since eroded away. Remains of the earliest vertebrates may never be found.
By the close of the Silurian, all known orders of jawless vertebrates had evolved, except perhaps the modern cyclostomes, which are without the hard parts that ordinarily are preserved as fossils. Cyclostomes were unknown as fossils until 1968, when a lamprey of modern body structure was reported from the Middle Pennsylvanian of Illinois, in deposits more than 300 million years old. Fossil evidence of the four orders of armoured jawless vertebrates is absent from deposits later than the Devonian. Presumably, these vertebrates became extinct at that time, being replaced by the more efficient and probably more aggressive placoderms, acanthodians, selachians (sharks and relatives), and by early bony fishes. Cyclostomes survived probably because early on they evolved from anaspid agnathans and developed a rasping tonguelike structure and a sucking mouth, enabling them to prey on other fishes. With this way of life they apparently had no competition from other fish groups. Cyclostomes, the hagfishes and lampreys, were once thought to be closely related because of the similarity in their suctorial mouths, but it is now understood that the hagfishes, order Myxiniformes, are the most primitive living chordates, and they are classified separately from the lampreys, order Petromyzontiformes.
Early jawless vertebrates probably fed on tiny organisms by filter feeding, as do the larvae of their descendants, the modern lampreys. The gill cavity of the early agnathans was large. It is thought that small organisms taken from the bottom by a nibbling action of the mouth, or more certainly by a sucking action through the mouth, were passed into the gill cavity along with water for breathing. Small organisms then were strained out by the gill apparatus and directed to the food canal. The gill apparatus thus evolved as a feeding, as well as a breathing, structure. The head and gills in the agnathans were protected by a heavy dermal armour; the tail region was free, allowing motion for swimming.
Most important for the evolution of fishes and vertebrates in general was the early appearance of bone, cartilage, and enamel-like substance. These materials became modified in later fishes, enabling them to adapt to many aquatic environments and finally even to land. Other basic organs and tissues of the vertebrates—such as the central nervous system, heart, liver, digestive tract, kidney, and circulatory system— undoubtedly were present in the ancestors of the agnathans. In many ways, bone, both external and internal, was the key to vertebrate evolution.
The next class of fishes to appear was the Acanthodii, containing the earliest known jawed vertebrates, which arose in the Late Silurian, more than 416 million years ago. The acanthodians declined after the Devonian but lasted into the Early Permian, a little less than 280 million years ago. The first complete specimens appear in Lower Devonian freshwater deposits, but later in the Devonian and Permian some members appear to have been marine. Most were small fishes, not more than 75 cm (approximately 30 inches) in length.
We know nothing of the ancestors of the acanthodians. They must have arisen from some jawless vertebrate, probably in fresh water. They appear to have been active swimmers with almost no head armour but with large eyes, indicating that they depended heavily on vision. Perhaps they preyed on invertebrates. The rows of spines and spinelike fins between the pectoral and pelvic fins give some credence to the idea that paired fins arose from “fin folds” along the body sides.
The relationships of the acanthodians to other jawed vertebrates are obscure. They possess features found in both sharks and bony fishes. They are like early bony fishes in possessing ganoidlike scales and a partially ossified internal skeleton. Certain aspects of the jaw appear to be more like those of bony fishes than sharks, but the bony fin spines and certain aspects of the gill apparatus would seem to favour relationships with early sharks. Acanthodians do not seem particularly close to the Placodermi, although, like the placoderms, they apparently possessed less efficient tooth replacement and tooth structure than the sharks and the bony fishes, possibly one reason for their subsequent extinction.
Explore Jan 20, 2011 #254
How lucky am I? Two weeks in a row I have found and managed to capture an image of this rare orange and brilliant blue beauty! Both times I was shaking with excitement! I had been telling Albert about the Atala and shown him its picture. He was the one who said, "What's that? I think I see one!" And the chase began.
The Atala is a strange butterfly to photograph. The colored areas are vague at the margins so the pigment looks like it has been dusted on the wings and body a bit carelessly. But look at its marvelous tones... deep velvety blue, bright electric blue and brilliant red orange! It is fast moving so getting a shot at all is a thrill! Usually looks like a vibrant patch of astounding flying color and it's gone'. The Atala is also unique in that its bright colors are on the underside of the wings not the top, qnd it keeps its wings closed and upright as soon as it lands. The topside of the Atala's wings is quite plain and darkr. No big, brilliant open-wing shots like you can take of a Monarch!
Interdependencies in nature once again. This marvelous creature owes its life to the Florida Coontie which was almost wiped out after being the money crop of the first Florida pioneers. Without the Coontie, this beauty will be gone.
The short, woody stem and rootstock of the Coontie grows almost completely underground and produces a terminal crown of stiff, evergreen, pinnate leaves up to 3 feet long. The brown, fleshy, erect, female or seed-bearing cones are pendent when mature. Coontie plants contain a natural toxin, which atala larvae accumulate in their bodies and use to repel birds. Without coontie, adult atalas have no place to lay eggs. No eggs means no new generations. .
Wild coonties’ demise began with starch: Long before Europeans arrived in Florida, Native Americans used coontie as a source of starch. Coontie, in fact, is a Seminole word that means “bread” or “white root” because the roots can be made into flour.
From "The Forgotten Frontier: Florida Through the Lens of Ralph Middleton Munroe" by Arva Moore Parks: 'Behind the hammock land the pine and palmetto country seemed to go on forever. Sending roots into the crevices of stone, the tall pine and its companions, the bushy palmetto and the fernlike comptie (Zamia), thrived in what seemed like solid rock. Althought not as glamorous as the hammock, the pineland was the backbone of the land. The heart of the pine became the foundation of the pioneer home; the palmetto, for thatch, became the roof; and the starch made from the root of the comptie filled the pionerer's stomach."
Cootie is sporadic in pinelands and hammocks throughout nearly all peninsular Florida and the Keys. In an effort to preserve the Atala, the coontie is being used increasingly in landscaping. Here in Miami, it is growing at Arch Creek East Environmental Preserve. Arch Creek was an early Tequesta Indian settlement here in North Miami. Arch Creek is spanned by a natural limestone bridge. Early photographs of Miami show the bridge in all its beauty. Compromised now by encroaching housing and roadways.
The Tequesta Indians thrived in Arch Creek and the surrounding area. There was an oak hammock near the creek which provided shade as well as edible plants, nuts and berries. Biscayne Bay, less than a half mile away, was a prime food source for the Tequestas. There they caught shellfish, shark, manatee and turtle. North of the hammock were pine flatlands, which sheltered the all-important coontie plant (Zamia integrifolia), whose roots the Indians ground to make an edible starch product.
Tequesta habitation sites characteristically have midden areas or Indian garbage dumps. The gradual decomposition of refuse, including plant material and animal bones, produces a rich black soil. Many artifacts have been preserved in the soil, and archaeologists have uncovered many of them, such as bone points, shell tools and pottery shards. During their centuries of occupation (from c. 400 A.D. to c. 1200 A.D.), the Arch Creek Tequestas had what appears to be a fairly comfortable lifestyle, supported by the abundant natural resources at the site.
Around 1858 two ambitious pioneers used the creek and its natural bridge as a site for a coontie starch mill. These early entrepreneurs learned how to clean the poisonous roots and dammed up the waterway under the bridge diverting the flow through a sluice they carved out of a solid limestone bank. The water turned a wooden wheel attached to a nail-studded grinder, which mashed the cootie roots into a paste-like pulp. The resulting starch was then soaked and strained to remove any remaining poison. Laid out in wooden racks, the starch dried quickly and the sun bleached it white. In the early 1900s, several commercial factories in South Florida processed coontie roots for the manufacture of arrowroot biscuits. But coontie starch was not as successful as the pioneers thought, and the mill was abandoned several years later. The water sluice was filled in and paved over, and was not discovered until archaeologists excavated it in 1972.
Arch Creek East Environmental Preserve, North Miami, FL.
See my set, Woods, weeds and streams.
Florida Arrowroot, Coontie, Comptie, Zamia
Fairchild Tropical Botanic Garden, Miami, FL.
See my set, Woods, weeds and streams.
Hōʻawa or Kona cheesewood
Pittosporaceae (Pittosporum family)
Endemic to the Hawaiian Islands (Kohala Mountains south to the Kaʻū District, Hawaiʻi Island)
Oʻahu (Cultivated)
The Hawaiian crow, or ʻalalā, (Corvus tropicus) fed on this hōʻawa, attracted by the bright orange inside color of the ripe fruit capsules and dark seeds and thus ensuring the spread of the plants. However, ʻalalā are now extremely rare and populations of hōʻawa in the birds former range are becoming very scarce as a result. This is a classic example of how interdependent native Hawaiian plants and animals are in the natural ecosystem.
The early Hawaiians used the wood to make gunwales for canoes.
The outer layer of the fruit valves were used medicinally. They were pounded and used externally on sores.
Flowers
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Fruit
www.flickr.com/photos/dweickhoff/8054150432/in/photolist-...
Habit
www.flickr.com/photos/dweickhoff/5188406532/in/photolist-...
Etymology
The generic name Pittosporum is derived from the Greek pittos, pitch, and sporos, seed, in reference to the film of viscid resin covering the black seeds.
The specific epithet hosmeri is named in honor of Ralph Sheldon Hosmer (1874-1963), Hawaiʻi's first territorial forester. Hosmer's Grove, Maui is one of Hosmer's forestry experimental using non-native species he planted in 1910. Unfortunately, some of the species are now invasive on Maui, such as the Mexican weeping pine, Monterrey pine, and eucalyptus, displacing the native plants.
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
Kālī, also known as Kālikā (Sanskrit: कालिका), is the Hindu goddess associated with empowerment, shakti. She is the fierce aspect of the goddess Durga (Parvati). The name Kali comes from kāla, which means black, time, death, lord of death: Shiva. Since Shiva is called Kāla— the eternal time — the name of Kālī, his consort, also means "Time" or "Death" (as in "time has come"). Hence, Kāli is the Goddess of Time and Change. Although sometimes presented as dark and violent, her earliest incarnation as a figure of annihilation of evil forces still has some influence. Various Shakta Hindu cosmologies, as well as Shākta Tantric beliefs, worship her as the ultimate reality or Brahman. Comparatively recent devotional movements largely conceive Kāli as a benevolent mother goddess. Kālī is represented as the consort of Lord Shiva, on whose body she is often seen standing. Shiva lies in the path of Kali, whose foot on Shiva subdues her anger.
ETYMOLOGY
Kālī is the feminine form of kālam ("black, dark coloured"). Kāla primarily means "time" but also means "black" in honor of being the first creation before light itself. Kālī means "the black one" and refers to her being the entity of "time" or "beyond time." Kāli is strongly associated with Shiva, and Shaivas derive the masculine Kāla (an epithet of Shiva) to come from her feminine name. A nineteenth-century Sanskrit dictionary, the Shabdakalpadrum, states: कालः शिवः। तस्य पत्नीति - काली। kālaḥ śivaḥ। tasya patnīti kālī - "Shiva is Kāla, thus, his consort is Kāli" referring to Devi Parvathi being a manifestation of Devi MahaKali.
Other names include Kālarātri ("black night"), as described above, and Kālikā ("relating to time"). Coburn notes that the name Kālī can be used as a proper name, or as a description of color.
Kāli's association with darkness stands in contrast to her consort, Shiva, who manifested after her in creation, and who symbolises the rest of creation after Time is created. In his supreme awareness of Maya, his body is covered by the white ashes of the cremation ground (Sanskrit: śmaśāna) where he meditates, and with which Kāli is also associated, as śmaśāna-kālī.
ORIGINS
Hugh Urban notes that although the word Kālī appears as early as the Atharva Veda, the first use of it as a proper name is in the Kathaka Grhya Sutra (19.7). Kali is the name of one of the seven tongues of Agni, the [Rigvedic] God of Fire, in the Mundaka Upanishad (2:4), but it is unlikely that this refers to the goddess. The first appearance of Kāli in her present form is in the Sauptika Parvan of the Mahabharata (10.8.64). She is called Kālarātri (literally, "black night") and appears to the Pandava soldiers in dreams, until finally she appears amidst the fighting during an attack by Drona's son Ashwatthama. She most famously appears in the sixth century Devi Mahatmyam as one of the shaktis of Mahadevi, and defeats the demon Raktabija ("Bloodseed"). The tenth-century Kalika Purana venerates Kāli as the ultimate reality.
According to David Kinsley, Kāli is first mentioned in Hinduism as a distinct goddess around 600 CE, and these texts "usually place her on the periphery of Hindu society or on the battlefield." She is often regarded as the Shakti of Shiva, and is closely associated with him in various Puranas. The Kalika Purana depicts her as the "Adi Shakti" (Fundamental Power) and "Para Prakriti" or beyond nature.
WORSHIP & MANTRA
Kali could be considered a general concept, like Durga, and is mostly worshiped in the Kali Kula sect of worship. The closest way of direct worship is Maha Kali or Bhadra Kali (Bhadra in Sanskrit means 'gentle'). Kali is worshiped as one of the 10 Mahavidya forms of Adi Parashakti (Goddess Durga) or Bhagavathy according to the region. The mantra for worship is called Devi Argala Stotram.
Sanskrit: सर्वमङ्गलमाङ्गल्ये शिवे सर्वार्थसाधिके । शरण्ये त्र्यम्बके गौरि नारायणि नमोऽस्तु ते ॥
ॐ जयंती मंगल काली भद्रकाली कपालिनी । दुर्गा क्षमा शिवा धात्री स्वाहा स्वधा नमोऽस्तुते ॥
(Sarvamaṅgalamāṅgalyē śivē sarvārthasādhikē . śaraṇyē tryambakē gauri nārāyaṇi namō'stu tē.
Oṃ jayantī mangala kālī bhadrakālī kapālinī . durgā kṣamā śivā dhātrī svāhā svadhā namō'stutē.)
TANTRA
Goddesses play an important role in the study and practice of Tantra Yoga, and are affirmed to be as central to discerning the nature of reality as are the male deities. Although Parvati is often said to be the recipient and student of Shiva's wisdom in the form of Tantras, it is Kāli who seems to dominate much of the Tantric iconography, texts, and rituals. In many sources Kāli is praised as the highest reality or greatest of all deities. The Nirvana-tantra says the gods Brahma, Vishnu, and Shiva all arise from her like bubbles in the sea, ceaselessly arising and passing away, leaving their original source unchanged. The Niruttara-tantra and the Picchila-tantra declare all of Kāli's mantras to be the greatest and the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra all proclaim Kāli vidyas (manifestations of Mahadevi, or "divinity itself"). They declare her to be an essence of her own form (svarupa) of the Mahadevi.
In the Mahanirvana-tantra, Kāli is one of the epithets for the primordial sakti, and in one passage Shiva praises her:
At the dissolution of things, it is Kāla [Time] Who will devour all, and by reason of this He is called Mahākāla [an epithet of Lord Shiva], and since Thou devourest Mahākāla Himself, it is Thou who art the Supreme Primordial Kālika. Because Thou devourest Kāla, Thou art Kāli, the original form of all things, and because Thou art the Origin of and devourest all things Thou art called the Adya [the Primordial One]. Re-assuming after Dissolution Thine own form, dark and formless, Thou alone remainest as One ineffable and inconceivable. Though having a form, yet art Thou formless; though Thyself without beginning, multiform by the power of Maya, Thou art the Beginning of all, Creatrix, Protectress, and Destructress that Thou art.
The figure of Kāli conveys death, destruction, and the consuming aspects of reality. As such, she is also a "forbidden thing", or even death itself. In the Pancatattva ritual, the sadhaka boldly seeks to confront Kali, and thereby assimilates and transforms her into a vehicle of salvation. This is clear in the work of the Karpuradi-stotra, a short praise of Kāli describing the Pancatattva ritual unto her, performed on cremation grounds. (Samahana-sadhana)
He, O Mahākāli who in the cremation-ground, naked, and with dishevelled hair, intently meditates upon Thee and recites Thy mantra, and with each recitation makes offering to Thee of a thousand Akanda flowers with seed, becomes without any effort a Lord of the earth. Oh Kāli, whoever on Tuesday at midnight, having uttered Thy mantra, makes offering even but once with devotion to Thee of a hair of his Shakti [his energy/female companion] in the cremation-ground, becomes a great poet, a Lord of the earth, and ever goes mounted upon an elephant.
The Karpuradi-stotra clearly indicates that Kāli is more than a terrible, vicious, slayer of demons who serves Durga or Shiva. Here, she is identified as the supreme mistress of the universe, associated with the five elements. In union with Lord Shiva, she creates and destroys worlds. Her appearance also takes a different turn, befitting her role as ruler of the world and object of meditation. In contrast to her terrible aspects, she takes on hints of a more benign dimension. She is described as young and beautiful, has a gentle smile, and makes gestures with her two right hands to dispel any fear and offer boons. The more positive features exposed offer the distillation of divine wrath into a goddess of salvation, who rids the sadhaka of fear. Here, Kali appears as a symbol of triumph over death.
BENGALI TRADITION
Kali is also a central figure in late medieval Bengali devotional literature, with such devotees as Ramprasad Sen (1718–75). With the exception of being associated with Parvati as Shiva's consort, Kāli is rarely pictured in Hindu legends and iconography as a motherly figure until Bengali devotions beginning in the early eighteenth century. Even in Bengāli tradition her appearance and habits change little, if at all.
The Tantric approach to Kāli is to display courage by confronting her on cremation grounds in the dead of night, despite her terrible appearance. In contrast, the Bengali devotee appropriates Kāli's teachings adopting the attitude of a child, coming to love her unreservedly. In both cases, the goal of the devotee is to become reconciled with death and to learn acceptance of the way that things are. These themes are well addressed in Rāmprasād's work. Rāmprasād comments in many of his other songs that Kāli is indifferent to his wellbeing, causes him to suffer, brings his worldly desires to nothing and his worldly goods to ruin. He also states that she does not behave like a mother should and that she ignores his pleas:
Can mercy be found in the heart of her who was born of the stone? [a reference to Kali as the daughter of Himalaya]
Were she not merciless, would she kick the breast of her lord?
Men call you merciful, but there is no trace of mercy in you, Mother.
You have cut off the heads of the children of others, and these you wear as a garland around your neck.
It matters not how much I call you "Mother, Mother." You hear me, but you will not listen.
To be a child of Kāli, Rāmprasād asserts, is to be denied of earthly delights and pleasures. Kāli is said to refrain from giving that which is expected. To the devotee, it is perhaps her very refusal to do so that enables her devotees to reflect on dimensions of themselves and of reality that go beyond the material world.
A significant portion of Bengali devotional music features Kāli as its central theme and is known as Shyama Sangeet ("Music of the Night"). Mostly sung by male vocalists, today even women have taken to this form of music. One of the finest singers of Shyāma Sāngeet is Pannalal Bhattacharya.
In Bengal, Kāli is venerated in the festival Kali Puja, the new moon day of Ashwin month which coincides with Diwali festival.
In a unique form of Kāli worship, Shantipur worships Kāli in the form of a hand painted image of the deity known as Poteshwari (meaning the deity drawn on a piece of cloth).
LEGENDS
SLAYER OF RAKTABIJA
In Kāli's most famous legend, Devi Durga (Adi Parashakti) and her assistants, the Matrikas, wound the demon Raktabija, in various ways and with a variety of weapons in an attempt to destroy him. They soon find that they have worsened the situation for with every drop of blood that is dripped from Raktabija he reproduces a clone of himself. The battlefield becomes increasingly filled with his duplicates. Durga, in need of help, summons Kāli to combat the demons. It is said, in some versions, that Goddess Durga actually assumes the form of Goddess Kāli at this time. The Devi Mahatmyam describes:
Out of the surface of her (Durga's) forehead, fierce with frown, issued suddenly Kali of terrible countenance, armed with a sword and noose. Bearing the strange khatvanga (skull-topped staff ), decorated with a garland of skulls, clad in a tiger's skin, very appalling owing to her emaciated flesh, with gaping mouth, fearful with her tongue lolling out, having deep reddish eyes, filling the regions of the sky with her roars, falling upon impetuously and slaughtering the great asuras in that army, she devoured those hordes of the foes of the devas.
Kali destroys Raktabija by sucking the blood from his body and putting the many Raktabija duplicates in her gaping mouth. Pleased with her victory, Kali then dances on the field of battle, stepping on the corpses of the slain. In the Devi Mahatmya version of this story, Kali is also described as a Matrika and as a Shakti or power of Devi. She is given the epithet Cāṃuṇḍā (Chamunda), i.e. the slayer of the demons Chanda and Munda. Chamunda is very often identified with Kali and is very much like her in appearance and habit.
DAKSHINA KALI
In her most famous pose as Daksinakali, popular legends say that Kali, becoming drunk on the blood of her victims on the battlefield, dances with destructive frenzy. She is about to destroy the whole universe when, urged by all the gods, Shiva lies in her way to stop her. In her fury, she fails to see the body of Shiva lying amongst the corpses on the battlefield and steps upon his chest. Realizing Shiva lies beneath her feet, her anger is pacified and she calms her fury. Though not included in any of the puranas, popular legends state that Kali was ashamed at the prospect of keeping her husband beneath her feet and thus stuck her tongue out in shame. The Devi-Bhagavata Purana, which goes into great depths about the goddess Kali, reveals the tongue's actual symbolism.
The characteristic icons that depict Kali are the following; unbridled matted hair, open blood shot eyes, open mouth and a drooping tongue; in her hands, she holds a Khadga (bent sword or scimitar) and a human head; she has a girdle of human hands across her waist and an enchanted Shiva lies beneath her feet. Each of these icons represent a deep philosophical epithet. The drooping out-stuck tongue represents her blood-thirst. Lord Shiva beneath her feet represents matter, as Kali is undoubtedly the primeval energy. The depiction of Kali on Shiva shows that without energy, matter lies "dead". This concept has been simplified to a folk-tale depicting a wife placing her foot on her husband and sticking her tongue out in shame. In tantric contexts, the tongue is seen to denote the element (guna) of rajas (energy and action) controlled by sattva.
If Kali steps on Shiva with her right foot and holds the sword in her left hand, she is considered to be Dakshina Kali. The Dakshina Kali Temple has important religious associations with the Jagannath Temple and it is believed that Daksinakali is the guardian of the kitchen of the Lord Jagannath Temple. Puranic tradition says that in Puri, Lord Jagannath is regarded as Daksinakalika. Goddess Dakshinakali plays an important role in the 'Niti' of Saptapuri Amavasya.
One South Indian tradition tells of a dance contest between Shiva and Kali. After defeating the two demons Sumbha and Nisumbha, Kali takes up residence in the forest of Thiruvalankadu or Thiruvalangadu. She terrorizes the surrounding area with her fierce, disruptive nature. One of Shiva's devotees becomes distracted while performing austerities, and asks Shiva to rid the forest of the destructive goddess. When Shiva arrives, Kali threatens him, claiming the territory as her own. Shiva challenges Kali to a dance contest; both of them dance and Kali matches Shiva in every step that he takes until Shiva takes the "Urdhvatandava" step, by vertically raising his right leg. Kali refuses to perform this step, which would not befit her as a woman, and became pacified.
SMASHAN KALI
If the Kali steps out with the left foot and holds the sword in her right hand, she is the terrible form of Mother, the Smashan Kali of the cremation ground. She is worshiped by tantrics, the followers of Tantra, who believe that one's spiritual discipline practiced in a smashan (cremation ground) brings success quickly. Sarda Devi, the consort of Ramakrishna Paramhansa, worshipped Smashan Kali at Dakshineshwar.
MATERNAL KALI
Another legend depicts the infant Shiva calming Kali. In this similar story, Kali has defeated her enemies on the battlefield and begun to dance out of control, drunk on the blood of the slain. To calm her down and to protect the stability of the world, Shiva is sent to the battlefield, as an infant, crying aloud. Seeing the child's distress, Kali ceases dancing to care for the helpless infant. She picks him up, kisses his head, and proceeds to breast feed the infant Shiva. This legend is notable because it shows Kali in her benevolent, maternal aspect, with which she is not usually identified.
MAHAKALI
Mahakali (Sanskrit: Mahākālī, Devanagari: महाकाली), literally translated as Great Kali, is sometimes considered as a greater form of Kali, identified with the Ultimate reality of Brahman. It can also be used as an honorific of the Goddess Kali, signifying her greatness by the prefix "Mahā-". Mahakali, in Sanskrit, is etymologically the feminized variant of Mahakala or Great Time (which is interpreted also as Death), an epithet of the God Shiva in Hinduism. Mahakali is the presiding Goddess of the first episode of the Devi Mahatmya. Here she is depicted as Devi in her universal form as Shakti. Here Devi serves as the agent who allows the cosmic order to be restored.
Kali is depicted in the Mahakali form as having ten heads, ten arms, and ten legs. Each of her ten hands is carrying a various implement which vary in different accounts, but each of these represent the power of one of the Devas or Hindu Gods and are often the identifying weapon or ritual item of a given Deva. The implication is that Mahakali subsumes and is responsible for the powers that these deities possess and this is in line with the interpretation that Mahakali is identical with Brahman. While not displaying ten heads, an "ekamukhi" or one headed image may be displayed with ten arms, signifying the same concept: the powers of the various Gods come only through Her grace.
ICONOGRAPHY
Kali is portrayed mostly in two forms: the popular four-armed form and the ten-armed Mahakali form. In both of her forms, she is described as being black in color but is most often depicted as blue in popular Indian art. Her eyes are described as red with intoxication, and in absolute rage, her hair is shown disheveled, small fangs sometimes protrude out of her mouth, and her tongue is lolling. She is often shown naked or just wearing a skirt made of human arms and a garland of human heads. She is also accompanied by serpents and a jackal while standing on a seemingly dead Shiva, usually right foot forward to symbolize the more popular Dakshinamarga or right-handed path, as opposed to the more infamous and transgressive Vamamarga or left-handed path.
In the ten-armed form of Mahakali she is depicted as shining like a blue stone. She has ten faces and ten feet and three eyes. She has ornaments decked on all her limbs. There is no association with Shiva.
The Kalika Purana describes Kali as possessing a soothing dark complexion, as perfectly beautiful, riding a lion, four-armed, holding a sword and blue lotuses, her hair unrestrained, body firm and youthful.
In spite of her seemingly terrible form, Kali Ma is often considered the kindest and most loving of all the Hindu goddesses, as she is regarded by her devotees as the Mother of the whole Universe. And because of her terrible form, she is also often seen as a great protector. When the Bengali saint Ramakrishna once asked a devotee why one would prefer to worship Mother over him, this devotee rhetorically replied, "Maharaj, when they are in trouble your devotees come running to you. But, where do you run when you are in trouble?"
According to Ramakrishna, darkness is the Ultimate Mother, or Kali:
My Mother is the principle of consciousness. She is Akhanda Satchidananda; indivisible Reality, Awareness, and Bliss. The night sky between the stars is perfectly black. The waters of the ocean depths are the same; The infinite is always mysteriously dark. This inebriating darkness is my beloved Kali.
SRI RAMAKRISHNA
This is clear in the works of such contemporary artists as Charles Wish, and Tyeb Mehta, who sometimes take great liberties with the traditional, accepted symbolism, but still demonstrate a true reverence for the Shakta sect.
POPULAR FORM
Classic depictions of Kali share several features, as follows:
Kali's most common four armed iconographic image shows each hand carrying variously a sword, a trishul (trident), a severed head and a bowl or skull-cup (kapala) catching the blood of the severed head.
Two of these hands (usually the left) are holding a sword and a severed head. The Sword signifies Divine Knowledge and the Human Head signifies human Ego which must be slain by Divine Knowledge in order to attain Moksha. The other two hands (usually the right) are in the abhaya (fearlessness) and varada (blessing) mudras, which means her initiated devotees (or anyone worshipping her with a true heart) will be saved as she will guide them here and in the hereafter.
She has a garland consisting of human heads, variously enumerated at 108 (an auspicious number in Hinduism and the number of countable beads on a Japa Mala or rosary for repetition of Mantras) or 51, which represents Varnamala or the Garland of letters of the Sanskrit alphabet, Devanagari. Hindus believe Sanskrit is a language of dynamism, and each of these letters represents a form of energy, or a form of Kali. Therefore she is generally seen as the mother of language, and all mantras.
She is often depicted naked which symbolizes her being beyond the covering of Maya since she is pure (nirguna) being-consciousness-bliss and far above prakriti. She is shown as very dark as she is brahman in its supreme unmanifest state. She has no permanent qualities - she will continue to exist even when the universe ends. It is therefore believed that the concepts of color, light, good, bad do not apply to her - she is the pure, un-manifested energy, the Adi-shakti.
SHIVA IN KALI ICONOGRAPHY
In both these images she is shown standing on the prone, inert or dead body of Shiva. There is a legend for the reason behind her standing on what appears to be Shiva's corpse, which translates as follows:
Once Kali had destroyed all the demons in battle, she began a terrific dance out of the sheer joy of victory. All the worlds or lokas began to tremble and sway under the impact of her dance. So, at the request of all the Gods, Shiva himself asked her to desist from this behavior. However, she was too intoxicated to listen. Hence, Shiva lay like a corpse among the slain demons in order to absorb the shock of the dance into himself. When Kali eventually stepped upon Shiva, she realized she was trampling and hurting her husband and bit her tongue in shame.
The story described here is a popular folk tale and not described or hinted in any of the puranas. The puranic interpretation is as follows:
Once, Parvati asks Shiva to chose the one form among her 10 forms which he likes most. To her surprise, Shiva reveals that he is most comfortable with her Kali form, in which she is bereft of her jewellery, her human-form, her clothes, her emotions and where she is only raw, chaotic energy, where she is as terrible as time itself and even greater than time. As Parvati takes the form of Kali, Shiva lies at her feet and requests her to place her foot on his chest, upon his heart. Once in this form, Shiva requests her to have this place, below her feet in her iconic image which would be worshiped throughout.
This idea has been explored in the Devi-Bhagavata Purana and is most popular in the Shyama Sangeet, devotional songs to Kali from the 12th to 15th centuries.
The Tantric interpretation of Kali standing on top of her husband is as follows:
The Shiv tattava (Divine Consciousness as Shiva) is inactive, while the Shakti tattava (Divine Energy as Kali) is active. Shiva and Kali represent Brahman, the Absolute pure consciousness which is beyond all names, forms and activities. Kali, on the other hand, represents the potential (and manifested) energy responsible for all names, forms and activities. She is his Shakti, or creative power, and is seen as the substance behind the entire content of all consciousness. She can never exist apart from Shiva or act independently of him, just as Shiva remains a mere corpse without Kali i.e., Shakti, all the matter/energy of the universe, is not distinct from Shiva, or Brahman, but is rather the dynamic power of Brahman. Hence, Kali is Para Brahman in the feminine and dynamic aspect while Shiva is the male aspect and static. She stands as the absolute basis for all life, energy and beneath her feet lies, Shiva, a metaphor for mass, which cannot retain its form without energy.
While this is an advanced concept in monistic Shaktism, it also agrees with the Nondual Trika philosophy of Kashmir, popularly known as Kashmir Shaivism and associated most famously with Abhinavagupta. There is a colloquial saying that "Shiva without Shakti is Shava" which means that without the power of action (Shakti) that is Mahakali (represented as the short "i" in Devanagari) Shiva (or consciousness itself) is inactive; Shava means corpse in Sanskrit and the play on words is that all Sanskrit consonants are assumed to be followed by a short letter "a" unless otherwise noted. The short letter "i" represents the female power or Shakti that activates Creation. This is often the explanation for why She is standing on Shiva, who is either Her husband and complement in Shaktism or the Supreme Godhead in Shaivism.
To properly understand this complex Tantric symbolism it is important to remember that the meaning behind Shiva and Kali does not stray from the non-dualistic parlance of Shankara or the Upanisads. According to both the Mahanirvana and Kularnava Tantras, there are two distinct ways of perceiving the same absolute reality. The first is a transcendental plane which is often described as static, yet infinite. It is here that there is no matter, there is no universe and only consciousness exists. This form of reality is known as Shiva, the absolute Sat-Chit-Ananda - existence, knowledge and bliss. The second is an active plane, an immanent plane, the plane of matter, of Maya, i.e., where the illusion of space-time and the appearance of an actual universe does exist. This form of reality is known as Kali or Shakti, and (in its entirety) is still specified as the same Absolute Sat-Chit-Ananda. It is here in this second plane that the universe (as we commonly know it) is experienced and is described by the Tantric seer as the play of Shakti, or God as Mother Kali.
From a Tantric perspective, when one meditates on reality at rest, as absolute pure consciousness (without the activities of creation, preservation or dissolution) one refers to this as Shiva or Brahman. When one meditates on reality as dynamic and creative, as the Absolute content of pure consciousness (with all the activities of creation, preservation or dissolution) one refers to it as Kali or Shakti. However, in either case the yogini or yogi is interested in one and the same reality - the only difference being in name and fluctuating aspects of appearance. It is this which is generally accepted as the meaning of Kali standing on the chest of Shiva.
Although there is often controversy surrounding the images of divine copulation, the general consensus is benign and free from any carnal impurities in its substance. In Tantra the human body is a symbol for the microcosm of the universe; therefore sexual process is responsible for the creation of the world. Although theoretically Shiva and Kali (or Shakti) are inseparable, like fire and its power to burn, in the case of creation they are often seen as having separate roles. With Shiva as male and Kali as female it is only by their union that creation may transpire. This reminds us of the prakrti and purusa doctrine of Samkhya wherein prakāśa- vimarśa has no practical value, just as without prakrti, purusa is quite inactive. This (once again) stresses the interdependencies of Shiva and Shakti and the vitality of their union.
Gopi Krishna proposed that Kali standing on the dead Shiva or Shava (Sanskrit for dead body) symbolised the helplessness of a person undergoing the changing process (psychologically and physiologically) in the body conducted by the Kundalini Shakti.
DEVELOPMENT
In the later traditions, Kali has become inextricably linked with Shiva. The unleashed form of Kali often becomes wild and uncontrollable, and only Shiva is able to tame her just as only Kali can tame Shiva. This is both because she is often a transformed version of one of his consorts and because he is able to match her wildness.
The ancient text of Kali Kautuvam describes her competition with Shiva in dance, from which the sacred 108 Karanas appeared. Shiva won the competition by acting the urdva tandava, one of the Karanas, by raising his feet to his head. Other texts describe Shiva appearing as a crying infant and appealing to her maternal instincts. While Shiva is said to be able to tame her, the iconography often presents her dancing on his fallen body, and there are accounts of the two of them dancing together, and driving each other to such wildness that the world comes close to unravelling.
Shiva's involvement with Tantra and Kali's dark nature have led to her becoming an important Tantric figure. To the Tantric worshippers, it was essential to face her Curse, the terror of death, as willingly as they accepted Blessings from her beautiful, nurturing, maternal aspect. For them, wisdom meant learning that no coin has only one side: as death cannot exist without life, so life cannot exist without death. Kali's role sometimes grew beyond that of a chaos - which could be confronted - to that of one who could bring wisdom, and she is given great metaphysical significance by some Tantric texts. The Nirvāna-tantra clearly presents her uncontrolled nature as the Ultimate Reality, claiming that the trimurti of Brahma, Vishnu and Rudra arise and disappear from her like bubbles from the sea. Although this is an extreme case, the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra declare her the svarupa (own-being) of the Mahadevi (the great Goddess, who is in this case seen as the combination of all devis).
The final stage of development is the worshipping of Kali as the Great Mother, devoid of her usual violence. This practice is a break from the more traditional depictions. The pioneers of this tradition are the 18th century Shakta poets such as Ramprasad Sen, who show an awareness of Kali's ambivalent nature. Ramakrishna, the 19th century Bengali saint, was also a great devotee of Kali; the western popularity of whom may have contributed to the more modern, equivocal interpretations of this Goddess. Rachel McDermott's work, however, suggests that for the common, modern worshipper, Kali is not seen as fearful, and only those educated in old traditions see her as having a wrathful component. Some credit to the development of Devi must also be given to Samkhya. Commonly referred to as the Devi of delusion, Mahamaya or Durga, acting in the confines of (but not being bound by) the nature of the three gunas, takes three forms: Maha-Kali, Maha-Lakshmi and Maha-Saraswati, being her tamas-ika, rajas-ika and sattva-ika forms. In this sense, Kali is simply part of a larger whole.
Like Sir John Woodroffe and Georg Feuerstein, many Tantric scholars (as well as sincere practitioners) agree that, no matter how propitious or appalling you describe them, Shiva and Devi are simply recognizable symbols for everyday, abstract (yet tangible) concepts such as perception, knowledge, space-time, causation and the process of liberating oneself from the confines of such things. Shiva, symbolizing pure, absolute consciousness, and Devi, symbolizing the entire content of that consciousness, are ultimately one and the same - totality incarnate, a micro-macro-cosmic amalgamation of all subjects, all objects and all phenomenal relations between the "two." Like man and woman who both share many common, human traits yet at the same time they are still different and, therefore, may also be seen as complementary.
Worshippers prescribe various benign and horrific qualities to Devi simply out of practicality. They do this so they may have a variety of symbols to choose from, symbols which they can identify and relate with from the perspective of their own, ever-changing time, place and personal level of unfolding. Just like modern chemists or physicists use a variety of molecular and atomic models to describe what is unperceivable through rudimentary, sensory input, the scientists of ontology and epistemology must do the same. One of the underlying distinctions of Tantra, in comparison to other religions, is that it allows the devotee the liberty to choose from a vast array of complementary symbols and rhetoric which suit one's evolving needs and tastes. From an aesthetic standpoint, nothing is interdict and nothing is orthodox. In this sense, the projection of some of Devi's more gentle qualities onto Kali is not sacrilege and the development of Kali really lies in the practitioner, not the murthi.
A TIME magazine article of October 27, 1947, used Kali as a symbol and metaphor for the human suffering in British India during its partition that year.
Swami Vivekananda wrote his favorite poem Kali the Mother in 1898.
IN NEW AGE & NEOPAGANISM
An academic study of Western Kali enthusiasts noted that, "as shown in the histories of all cross-cultural religious transplants, Kali devotionalism in the West must take on its own indigenous forms if it is to adapt to its new environment." The adoption of Kali by the West has raised accusations of cultural appropriation:
A variety of writers and thinkers have found Kali an exciting figure for reflection and exploration, notably feminists and participants in New Age spirituality who are attracted to goddess worship. Kali is a symbol of wholeness and healing, associated especially with repressed female power and sexuality. [However, such interpretations often exhibit] confusion and misrepresentation, stemming from a lack of knowledge of Hindu history among these authors, draw upon materials written by scholars of the Hindu religious tradition. The majority instead rely chiefly on other popular feminist sources, almost none of which base their interpretations on a close reading of Kali's Indian background. The most important issue arising from this discussion - even more important than the question of 'correct' interpretation - concerns the adoption of other people's religious symbols. It is hard to import the worship of a goddess from another culture: religious associations and connotations have to be learned, imagined or intuited when the deep symbolic meanings embedded in the native culture are not available.
WIKIPEDIA
I thought this was a dead leaf until my friend Lynn told me it was a Zebra longwing chrsallis! I would have missed it altogether which nature no doubt designed to happen. But here it is so you will know next time you see one!
Zebra longwings lay their eggs on the Corky Passion Vine. Take a look at its tightly wrapped tendrils and the chewed way areas in the leaves!
I love the black spots on the almost- white caterpillar body, the prickly spines and, in the upper right corner, the quirky colorful striped stubby antennae. And these creatures are camouflaged by convincing antenna-like spines on the other end!
Mother Nature has created such marvelous interdependencies... Monarchs and Milkweed, Zebras and Passion Vines. Without one, we don't have the other! Important to remember!
The Zebra longwing begins mating right after it emerges from its chrysalis. The female lays 5 to 15 eggs on the leaves of Passion Vines. The caterpillar has a white body with long black spines and a yellow head. If weather conditions are right, the Zebra longwing can go from egg to butterfly in a little over 3 weeks.
When it is disturbed, the Zebra longwing butterfly makes a creaking sound by wiggling its body. At night, large groups roost together on tree limbs. They return to the same roost night after night.
Zebra longwing caterpillars feed on the leaves of the Passion Vine which contain a toxin that gives the Zebra longwing butterfly an unpleasant taste and makes it poisonous to predators. The butterfly drinks the nectar of a wide range of flowers.
Zebra longwing, Heliconius charitonius
Corky Passion vine
Biscayne Park, FL
Cronología abreviada de la imposición y la entrega (Por. C. Fazio)
I
El pasado 22 de noviembre, la 51 reunión interparlamentaria México-Estados Unidos concluyó con la difusión de un comunicado conjunto, en el que la delegación estadunidense manifestó su interés "por una mayor interdependencia y seguridad energética de Norteamérica". En la reunión, Michael McCaul, presidente de la delegación visitante y del Comité de Seguridad Interior de la Cámara de Representantes de Estados Unidos, elogió el paquete de contrarreformas neoliberales impulsado por Enrique Peña y el Pacto por México y, tras mencionar los acuerdos transfronterizos de hidrocarburos de su país con México, abogó por una profundización de la "alianza energética" entre ambos y Canadá.
En el marco de las privatizaciones en curso de Petróleos Mexicanos (Pemex) y la Comisión Federal de Electricidad (CFE) en el Congreso mexicano, las "aspiraciones" de McCaul y los parlamentarios estadunidenses no fueron para nada inocentes. Abrevan en la histórica ambición anexionista y de clase que desde los tiempos del secretario de Estado William H. Seward, en la segunda mitad del siglo XIX, se expresó en un proyecto de control infraestructural y económico de dimensiones continentales que incluía la absorción de México y Canadá; proyecto revitalizado en documentos oficiales del gobierno de Franklyn Delano Roosevelt en 1941, cuando se diseñó la Doctrina de Áreas Ampliadas (Grand Area Doctrine), plan geopolítico de integración vertical imperial para la competencia comercial entre bloques, con eje en la noción de "seguridad nacional" estadunidense.
En su última fase, dicho proceso arranca a finales de los años 70 del siglo pasado, cuando el lobby petrolero texano logró colocar en la Oficina Oval a Ronald Reagan y George Bush padre. Veamos:
1973. El embargo de la Organización de Países Exportadores de Petróleo (OPEP) a Estados Unidos, a raíz de su apoyo a Israel en la guerra de Yom Kippur, exhibió su vulnerabilidad energética y generó un trauma geoestratégico. Desde entonces, de cara a cualquier interrupción futura del flujo de hidrocarburos (petróleo y gas natural) del golfo Pérsico, Washington priorizó por razones de "seguridad nacional" sus políticas hacia "fuentes amigables, estables y seguras" como Inglaterra, Canadá, México y Venezuela.
1979. La vinculación entre la seguridad, la dependencia estratégica y las iniciativas para la inclusión de Canadá y México en esquemas de "integración" de América del Norte ingresa como tema central de la seguridad nacional de Estados Unidos. Para dejar de ser "rehenes" de la OPEP y de cara a la pugna interimperialista con los megabloques económicos de la Unión Europea y el Asia/Pacífico (Japón y los tigres asiáticos) que desafían la hegemonía de Estados Unidos, ese año, cuando el tema del petróleo y el gas era casi un tabú en las relaciones bilateral y regional, Ronald Reagan promueve en su campaña por la Casa Blanca la "desvinculación" del petróleo mexicano y el gas natural canadiense del mercado mundial y la "regionalización" de los recursos hidrocarburíficos de ambos países bajo la idea de un "mercado común energético" de América del Norte.
Años 80. En el caso de México, los mayores obstáculos para la conformación de un mercomún energético en el área espacial y territorial de Norteamérica eran el nacionalismo revolucionario, con su artículo 27 constitucional, y la noción misma de la soberanía nacional mexicana. Para librar esos escollos, Washington optó por instrumentos "no militares" (es decir, financieros y monetarios derivados de las líneas de condicionalidad del Banco Mundial, el FMI y el BID atadas a la deuda externa) y de "inteligencia política" (cooptación-corrupción de gobernantes, políticos y empresarios y las presiones derivadas de sus eventuales vínculos con el tráfico de drogas y otros ilícitos).
Históricamente, al aparato militar y diplomático estadunidense no le ha sido difícil detectar esas vulnerabilidades, porque, como dijo el ex secretario de Estado de Woodrow Wilson, Robert Lansing, "dominar a México es extremadamente fácil porque basta con controlar a un solo hombre: el presidente". Labor que han venido desarrollando los emisarios de Washington desde el primer gobierno neoliberal de Miguel de la Madrid hasta el presente, con Enrique Peña, pasando por Carlos Salinas (líder de la facción santannista de lo que Manuel Buendía llamó "neopolkos"), Ernesto Zedillo, Vicente Fox y Felipe Calderón. En abono de lo anterior, y como señaló hace más de dos lustros John Saxe-Fernández en La compra-venta de México, desde 1982 se ha venido generalizando en México el "quintacolumnismo", es decir, una quinta columna integrada por un grupo de poder local colaboracionista, antinacional y entreguista, afín a un anexionismo vertical, subordinado y dependiente de Estados Unidos.
1991. Durante el gobierno salinista, en el marco de la primera guerra del golfo Pérsico, Timothy O’Leary dio a conocer que en una reunión celebrada en Toronto, el 12 de junio de ese año, Los Pinos y la Casa Blanca pactaron que "sin modificar la Constitución mexicana", el petróleo y las operaciones nacionales e internacionales de Pemex entraran en las negociaciones del Tratado de Libre Comercio de América del Norte (TLCAN o NAFTA, por sus siglas en inglés).
1994. Con la entrada en vigor del TLCAN, definido por el ex director de la CIA William Colby como un instrumento importante para "desvanecer" la soberanía mexicana y "reorientar" la función y la existencia misma de México como Estado nación, se profundizó el proceso de "constitucionalización del neoliberalismo disciplinario". Esto es, el ajuste del aparato normativo mexicano con el fin de garantizar "seguridad jurídica" a los inversionistas privados extranjeros, con especial fruición, la desde entonces furtiva, larvada e ilegal contrarreforma a los artículos 27 y 28 de la Constitución en materia energética: electricidad, agua, petróleo, gas natural y otros minerales considerados "críticos y estratégicos" por el Pentágono.
II
Con la entrada en vigor del Tratado de Libre Comercio de América del Norte (TLCAN) en 1994, Estados Unidos y los organismos financieros "internacionales" (BM, FMI, BID, verdaderos perros guardianes al servicio del Departamento del Tesoro y las compañías multinacionales), han venido avanzando sin límite de continuidad en el "cogobierno" o "manejo conjunto" del territorio nacional y sus recursos geoestratégicos. Incluida la privatización "multimodal" de la infraestructura (carreteras, puertos, aeropuertos, vías de ferrocarril, redes de fibra óptica, de electricidad e hidrocarburos), propósito principal del Plan Puebla Panamá (PPP), diseñado durante la administración de Ernesto Zedillo y profundizado con Vicente Fox.
2000-2001. Tras la elección de Fox en julio de 2000, Washington arreció en sus propósitos de transformar el espacio territorial mexicano, de adecuarlo con las nuevas mercancías, a los nuevos negocios y tecnologías. De cuadricularlo, ordenarlo y hacerlo funcional y "productivo".
Durante su campaña electoral, en un debate televisado con Al Gore en octubre de 2000, el entonces gobernador de Texas, George W. Bush, recuperó la idea de Reagan y su padre (George Walker Bush, ex director de la CIA y vicepresidente de los dos mandatos de Reagan, a quien sucedió en 1988) de formar un "mercomún energético de América del Norte". Dijo: "Le hablé (a Fox) de cómo sería mejor apresurar la exploración de gas natural en México y transportarlo a Estados Unidos para que seamos menos dependientes de fuentes externas de petróleo crudo". En febrero de 2001, el experto George Baker, directivo de Mexico Energy Intelligence, planteó que Bush podía ofrecer fondos para convertir a Pemex en la mejor empresa petrolera del mundo. "Por supuesto, tendría que ser una propuesta del presidente Fox, que no corresponde plantear al presidente Bush", dijo Baker. En marzo, Bush no tuvo empacho en afirmar que el gas encontrado en México era "hemisférico" y debía beneficiar a Estados Unidos. Afirmó entonces: "Una buena política energética es aquella que entiende que tenemos energía en nuestro hemisferio y cómo explotarlo mejor y transportarlo a los mercados". Poco antes, con Fox de anfitrión, el secretario de Energía de EU, Spencer Abraham, había logrado introducir en la Declaración de México −suscrita por los ministros de Energía del hemisferio− una frase que abogaba por la "integración energética" del continente. Allí quedó formado un grupo de trabajo trilateral (integrado por Abraham y los ministros del ramo de Canadá y México). "Encontramos que hay dependencia mutua, sin socios minoritarios ni socios mayoritarios", dijo entonces Abraham desafiando la ley que rige la fábula del tiburón y las sardinas.
La idea de crear "redes" o "corredores energéticos" a través de ductos transfronterizos para el intercambio de hidrocarburos, así como la integración eléctrica entre Estados Unidos, Canadá y México, fue retomada en la Cumbre de Quebec (abril de 2001), donde participaron 34 jefes de Estado y de gobierno de América. Uno de los compromisos de la cumbre fue "norteamericanizar los mercados de energía" −ante la deficiencia de Estados Unidos en la materia esgrimida por Bush−, para lo cual se requería "cambiar el marco legislativo y regulatorio" de los países involucrados.
En mayo de 2001, el presidente Bush −principal operativo del cártel petrolero-gasero texano conformado por las trasnacionales Exxon-Mobil, Halliburton, Enron y El Paso Corporation− dio a conocer su plan energético nacional (conocido como Plan Cheney), donde el combustible extranjero pasó a ser el eje del proyecto. En ese esquema, México fue definido como una "fuente primordial" para garantizar la "seguridad energética" de Estados Unidos.
Varios meses antes de los atentados contra las Torres Gemelas, el Grupo para el Desarrollo de una Política Energética Nacional, que elaboró el Plan Cheney, había mostrado un mapa de la República Mexicana que identificaba las cuencas de Burgos, Sabinas y Pedregosas, en el norte de México, frente a Texas (dominios del clan Bush), como las principales reservas de gas no explotado. En esa región, sugería el documento, podría darse una interrelación energética "natural". El grupo recomendó a Bush que instruyera a sus secretarios de Estado y de Energía para que, en consulta con la Comisión Reguladora de Energía, se revisaran los "permisos presidenciales" para la construcción de infraestructura que permita el cruce de petróleo, gas natural y electricidad, y se propongan las reformas a las regulaciones que sean necesarias para hacerlas compatibles con el comercio intrafronterizo.
Cuando en septiembre de 2001 Fox visitó a Bush en Washington, ambos recibieron la propuesta del Consejo Binacional México-Estados Unidos de llevar a cabo, cuanto antes, la integración energética de Norteamérica. El principal destinatario de la solicitud fue Fox: a él le recomendaron aumentar la inversión privada en Pemex; abrir el sector de refinación de crudo al capital extranjero; dividir en varias compañías la red de oleoductos mexicanos y acceder a una pronta integración eléctrica con Estados Unidos. Para todo ello, señalaron, hay opciones: "liberalizando los marcos regulatorios y legales". Es decir, modificando la Constitución mexicana.
2002. El 20 de septiembre de ese año Bush presentó su Estrategia de Seguridad Nacional en la Casa Blanca. Entre las nociones básicas del documento, una decía: "Debe mejorar la seguridad energética (de Estados Unidos). Fortaleceremos nuestra propia seguridad energética y la prosperidad compartida de la economía mundial, colaborando con nuestros aliados, socios comerciales y productores de energía". En buen romance, fue el anuncio estratégico de la Alianza para la Seguridad y la Prosperidad de América del Norte (Aspan), suscrita en Waco, Texas, el 23 de marzo de 2005.
III
Año 2005. Según lo definió entonces la llamada Fuerza de Tarea Independiente (sic) sobre el Futuro de Norteamérica −cuyos copresidentes eran el ex viceprimer ministro de Canadá, John Manley; el ex gobernador de Massachusetts, William Weld y el ex secretario mexicano de Hacienda, Pedro Aspe−, el nuevo "paradigma" en las relaciones de México con Estados Unidos y Canadá ha sido la Alianza para la Seguridad y la Prosperidad de América del Norte (ASPAN).
El "menú" del pacto trilateral, definido entonces por la Casa Blanca con el colaboracionismo de tecnoburócratas gubernamentales, asociaciones empresariales y círculos intelectuales conservadores y entreguistas de Canadá y México, incluyó seis puntos básicos de seguridad: militar, interna, energética, global, social y de acceso al agua dulce. No fue casual que los puntos de la agenda definían los intereses geoestratégicos de Washington; subordinaban el comercio a los asuntos de seguridad definidos en la doctrina Bush de guerra preventiva y lucha contra el "terrorismo", y perseguían una dirección única: la dominación imperial estadunidense en el siglo XXI.
Los objetivos claves del "nuevo acuerdo" −en cuya elaboración participó de manera activa Andrés Rozental Gutman, medio hermano del ex canciller del foxismo Jorge G. Castañeda− fueron desarrollar mecanismos de seguridad marítima, aérea y terrestre que permitieran hacer frente a cualquier "amenaza" en América del Norte; una estrategia energética basada en el incremento de la oferta para satisfacer las "necesidades" de la región (léase Estados Unidos), y facilitar inversiones en infraestructura energética, para las mejoras tecnológicas, la producción y el suministro confiable de energéticos, mejorando la "cooperación" en la materia.
En forma complementaria, un objetivo estratégico de la política petrolera del dúo Bush-Cheney fue persuadir u obligar a México y países productores del golfo Pérsico a que abrieran sus empresas estatales a la inversión multinacional privada. En ese sentido, en Waco, Bush aprovechó la extrema debilidad del presidente Fox y definió la nueva agenda, que los tecnoburócratas locales tratarían de rellenar después con regulaciones, estándares y modificaciones graduales, pequeñas pero sustanciales, de modo de ir "armonizando" la legislación mexicana con los intereses de Washington y las trasnacionales del sector energético.
A su vez, para garantizar "la producción y el suministro confiable de energéticos" en Norteamérica −que comenzaba ya a tomar forma como nuevo espacio geopolítico y geoeconómico−, los estrategas castrenses de Washington impulsaron la idea de un "perímetro exterior de seguridad", lo que colocó a Canadá y México bajo el manto militar nuclear del Comando Estadunidense de Defensa Aeroespacial (conocido como NORAD, por sus siglas en inglés), y su extensión al Comando Norte (creado en 2002), ambos bajo el mando del Pentágono, encargados de proteger de facto los suelos, mares y cielos trinacionales. La anuencia tácita de Fox al plan de seguridad de Bush, colocó desde entonces al territorio mexicano como blanco de cualquier contingencia bélica interimperialista. Pero, además, ese proyecto estadunidense que asumió a México como problema doméstico, incluyó el sellamiento militar del Golfo de México, desde los cabos de la Florida hasta la península de Yucatán, y el corrimiento de la frontera norte al istmo de Tehuantepec para controlar el tránsito de indocumentados mexicanos, centro y sudamericanos, según el diseño original del Plan Puebla-Panamá.
La ASPAN (el TLCAN militarizado), que desde su concreción ha venido funcionando con un "gobierno sombra" de las élites empresariales y militares de Estados Unidos y sus socios menores en Canadá y México, incluyó una integración energética transfronteriza (petróleo, gas natural, electricidad) subordinada a Washington y megaproyectos del capital trasnacional que subsumieron los criterios económicos a los de seguridad, justificando así acciones que de otro modo no podrían ser admitidas por ser violatorias de la soberanía nacional, y una normativa supranacional que hizo a un lado el control legislativo (según la Constitución, el Senado es el encargado de vigilar los acuerdos internacionales suscritos por el Poder Ejecutivo), mientras se impusieron leyes contrainsurgentes que criminalizaron la protesta y la pobreza y globalizaron el disciplinamiento social.
Año 2007. Ya bajo el mandato espurio de Felipe Calderón, la Iniciativa Mérida, anunciada por George W. Bush en Washington el 22 de octubre de 2007, fue diseñada como un paquete de asistencia militar en especie a México por un monto de mil 400 millones de dólares para el trienio 2008-2010. El "nuevo paradigma de cooperación" entre Estados Unidos y México en materia de seguridad estuvo dirigido a hacer frente a "amenazas comunes" asimétricas, mismas que fueron identificadas como organizaciones trasnacionales del crimen organizado, en particular las dedicadas al narcotráfico, el tráfico de armas, las actividades financieras ilícitas, el tráfico de divisas y la trata de personas. Con un dato adicional: la virtual equiparación desde la óptica punitiva estadunidense de tres términos y sus manifestaciones concretas: terroristas, narcotraficantes y migrantes sin documentación válida (indocumentados).
Símil del Plan Colombia, en su parte sustantiva, el millonario paquete de asistencia militar incluyó aviones y helicópteros de combate, barcos, lanchas; armamento y equipo bélico, radares y sofisticados instrumentos para monitoreo aéreo e intervención de comunicaciones; software para análisis de datos asociados a inteligencia financiera, y recursos para sufragar cursos de entrenamiento y asesorías del Pentágono, la CIA, el FBI, la DEA y otros organismos de seguridad estadunidenses a sus contrapartes mexicanas. También incluyó recursos para la instrumentación de reformas judiciales, penales y de procuración de justicia, áreas que de manera paulatina serían homologadas a las de Estados Unidos.
IV
Integrado de facto desde 2002 al "perímetro de seguridad" de Estados Unidos, el territorio de México quedó incluido en la zona bajo control del Comando Norte del Pentágono. A su vez, en el marco de la ASPAN (el TLCAN militarizado, 2005), la Iniciativa Mérida (2007) llevaría a una desnacionalización acelerada del sistema de seguridad interna. Desde entonces, Estados Unidos sería codiseñador de la estrategia de "seguridad nacional" mexicana, lo que, más allá de juegos semánticos, significó una cesión de soberanía.
Definida por el entonces embajador de EE.UU. en México, Antonio Garza, como el "proyecto más agresivo" jamás impulsado por la Casa Blanca en el hemisferio occidental, la Iniciativa Mérida fue diseñada en función de la agenda de seguridad de Washington. Las prioridades de la administración Bush fueron: guerra a las drogas (en el territorio mexicano); guerra al terrorismo (ídem); seguridad fronteriza (en los confines norte y sur de México); control sobre la seguridad pública y las distintas policías de México; penetración de las fuerzas armadas locales (Ejército y Marina de Guerra); construcción de instituciones y reglas de ley similares a las de Estados Unidos (homologación de leyes como parte de la integración silenciosa y subordinada de México).
En ese sentido, las contrarreformas calderonistas fueron parte de la agenda policial-militar-judicial-penal de EE.UU., ya que se encaminaron no sólo a la adopción de facto de medidas similares a las del "Estado de excepción" de la era Bush (Ley Patriota, Comisiones Militares, Ley Marcial), sino que también, vía la pretendida modificación o derogación de la Ley para Conservar la Neutralidad del País, buscaba permitir la proyección del poder militar del Pentágono (aéreo, naval y terrestre, incluyendo las fuerzas especiales), en el territorio nacional y los espacios marítimo y aéreo (lo que luego ocurrió de manera no tan encubierta, drones incluidos), y la creación de bases militares, a la postre denominadas Oficinas Bilaterales de Inteligencia o centros de fusión.
2008. La energía y la política irían de la mano desde comienzos de ese año. En los círculos financieros se afirmó entonces que la privatización de Petróleos Mexicanos (Pemex) estaba próxima. Pero para ello se requerían reformas constitucionales y el presidente Felipe Calderón necesitaba conseguir los votos en el Congreso del Partido Revolucionario Institucional (PRI).
En ese contexto se reveló que Pemex, la mayor empresa paraestatal y principal contribuyente fiscal de México, había establecido convenios de cooperación con cinco multinacionales: la angloholandesa Royal Dutch Shell; Petrobras, de Brasil; Statoil de Holanda; la canadiense Nexen y el gigante petrolero estadunidense Chevron-Texaco. Según autoridades de Pemex, se trataban de convenios "sin carácter comercial" en materia de investigación científica y tecnológica, apegados a los ordenamientos constitucionales y legales vigentes entonces en el país.
Sin embargo, en diciembre anterior La Jornada había denunciado que existía un convenio de carácter confidencial con la Shell, para realizar actividades de exploración en el campo petrolero de Chicontepec, Veracruz, lo que estaba vedado por la Constitución. Entonces se especuló que el llamado Proyecto Margarita permitiría posicionar a la empresa angloholandesa en el país, ante una eventual eliminación de las restricciones constitucionales a la inversión privada en el sector energético.
Pemex clasificó como "información confidencial" los resultados derivados de los acuerdos suscritos con esas cinco compañías, y asumió el compromiso de ocultar los datos al Instituto Federal de Acceso a la Información y Protección de Datos (Ifai). Si Pemex rompía la reserva de los convenios debería pagar una indemnización de 500 mil dólares por evento. Y en caso de una controversia entre ambas partes, ésta se tendría que dirimir en las cortes internacionales de conformidad con el reglamento de arbitraje de la Cámara Internacional de Comercio, con sede en París, Francia.
Calderón dijo que Pemex no se privatizaría, lo que a todas luces fue una actitud demagógica, ya que en 2003, siendo ministro de Energía en el gabinete de Vicente Fox, había abogado por la apertura al capital privado de la Compañía Federal de Electricidad (CFE), mediante adecuaciones al texto de los artículos 27 y 28 constitucionales, con el fin de otorgar "certidumbre jurídica" a los inversionistas extranjeros. Ahora sólo era cuestión de cambiar sector "eléctrico" por "energético".
No era secreto que los distintos gobiernos neoliberales habían venido suscribiendo acuerdos inconfesables con empresas internacionales como el firmado con Shell. Entre los trucos semánticos que intentaban ocultar la privatización por partes de Pemex al margen de la Constitución, se había llegado a hablar de "acuerdos verbales", alianzas "sin documento alguno", convenios de "colaboración" y "pactos sin carácter comercial."
El 4 de marzo, en horario estelar, el gobierno de Calderón puso en marcha una millonaria estrategia propagandística televisiva dirigida a convencer a la población sobre la necesidad de que Pemex se asociara con empresas privadas, nacionales y extranjeras, para explorar "un tesoro escondido" a 3 mil metros de profundidad en el golfo de México. En lo que fue descrito como un doble juego gubernamental para abrir el sector de los energéticos al capital privado, se reveló la existencia de dos versiones del espot oficial: en el portal de YouTube, el promocional, que incluía gráficas satelitales e imágenes en tercera dimensión, hablaba de "alianzas" estratégicas con empresas privadas para la exploración en aguas profundas; pero esa palabra fue mutilada en la televisión abierta, lo que constituyó una manipulación intencional para ocultar que la iniciativa era en pro de una "alianza estratégica" o de "cuates", de la administración Calderón con los tiburones del sector energético trasnacional.
www.jornada.unam.mx/2013/11/25/opinion/021a1pol
www.jornada.unam.mx/2013/12/09/opinion/027a1pol
There's a feeling of promise in the air,
A feeling of promise everywhere -
A promise of singing birds and bees,
A promise of fruit on barren trees.
A promise of gardens blooming gay,
A promise of summer comes one day,
A promise of warm and sunny skies,
A promise that nothing ever dies.
A promise of beauty yet unseen,
A promise of brown earth clothed in green,
A promise of warmth and light and cheer,
A promise of hope this time of year.
** ** ** ** **
It is comforting to know that our lives are purposeful, albeit we are each spinning our individual threads, lending texture, color, pattern, to the big design that is serving us all.Our actions, thoughts, and our values compliment the entire human race. We are all heading toward the same destination and our paths may cross on occasion, intersect periodically, and veer off in singleness of purpose when inspired.
We are interdependent. Each one of us is giving what we are called upon to give when we are in a right relationship with God, who is the Master artist in the designs we are creating.
** ** ** ** ** **
... your own completeness is only realized in Christ. (Colossians 2:10).
** ** ** ** ** **
Sasbahu Temple, also called the Sas-Bahu Mandir, Sas-Bahu Temples, Sahastrabahu Temple or Harisadanam temple, is an 11th-century twin temple in Gwalior, Madhya Pradesh, India. Near the Gwalior Fort and dedicated to Vishnu in his Padmanabha form, like most Hindu and Jain temples in this region, it is mostly in ruins and was badly damaged from numerous invasions and Hindu-Muslim wars in the region. It was built in 1093 by King Mahipala of the Kachchhapaghata dynasty, according to an inscription found in the larger of the twin temple. The twin temples are situated in the Gwalior Fort.
The temple's tower and sanctum has been destroyed, but its architecture and damaged carvings can still be appreciated from the ruins. The jagati platform is 100 feet (30 m) long and 63 feet (19 m) wide, on a square plan. The temple was three-storeyed, which was one of its distinguishing features and sophistication. It followed a central cluster concept, states Adam Hardy. The surviving elements of the temple are the entrance porch and the mandapa. According to James Harle, though the prasada (tower, spire) no longer exists, the triple storey plan with a cruciform foundation and balconies suggests that it had a North Indian Bhumija style architecture. This style, states Harle, is marked by a well proportioned superstructure, its "regularly arranged little subordinate sikharas strung out like gigantic beaded garlands".
This temple mainly has three entrances from three different directions. In the fourth direction, there is a room which is currently closed. The entire temple is covered with carvings, notably 4 idols of Brahma, Vishnu and Saraswati above its entrance door. The pillar carvings show Vaishnavism, Shaivism and Shaktism related carvings. The larger temple ornamentation covers all the exterior walls and all surviving interior surfaces.
The twin temple, like elsewhere in India, has locally been called Sasbahu temple. The word Sasbahu means "mother-in-law, bride" or "a mother with her daughter-in-law", an association that implies their being together and interdependent. The Sas temple is typically the larger older temple of the twin. The Gwalior Sasbahu temple follows this style, but both temples are dedicated to Vishnu. Only the Sas temple has survived in some form, the Bahu temple is a shell structure of the original one storey with a highly ornate door frame and its defaced wall reliefs surviving. The remnants of the Bahu temple at Gwalior suggest that it may have been a smaller version of the Saas temple.
The Sas temple has a square sanctum attached to a rectangular two storey antarala and a closed three storey mandapa with three entrances. The temple main entrance porch has four carved Ruchaka ghatapallava-style pillars that are load-bearing. The walls and lintels are intricately carved, though much defaced. On the lintel of the entrances, friezes of Krishna-leela scenes are carved inside, while the outer side narrate legends from other Hindu texts. Above the lintel is Garuda, the vahana of Vishnu.
The Bahu temple also has a square sanctum with 9.33 feet (2.84 m) side, with four central pillars. Its maha-mandapa is also a square with 23.33 feet (7.11 m) side, with twelve pillars. The temple, like most Malwa and Rajputana historic temples, provides multiple entrances to the devotee. The roof consists of two rotated squares that intersect to form an octagon capped by successive overlapping circles. The pillars have octagonal bases as well, with girls carved but these have been defaced and mutilated. The sanctum has an image of damaged Vishnu, next to whom stands Brahma holding the Vedas on one side and Shiva holding the trident on the other side.
+ 3 in comments - Get Pushed Round 14
Subtitle #1 "Ya can't live with 'em and ya can't live without 'em"
Subtitle #2 "I'm surprised I haven't killed him by now."
This Get Pushed Round 14 challenge was offered by Mike (mswickedmonton) (a photographer with a great eye) who wrote "my primary challenge to you is to illustrate in a photograph, as obvious as possible... Yin and Yang."
"Two distinct elements in one photo that are (or close to) polar opposites or seemingly contrary forces that are somehow interconnected and interdependent in one world, one photo. Some may also refer to it as Order and Chaos."
"It makes no matter if the items are manmade, of nature, human, random stuff as you see it or, staged with props, or any combination thereof just so long as the opposite nature of the two primary elements is relatively obvious to most viewers and little or no post-processing is used (Minor sharpening, contrast, cropping, etc, okay, adding or deleting elements/effects in Photoshop, not okay, 'k)."
Wikipedia states that Yin and Yang, "polar opposites or seemingly contrary forces are interconnected and interdependent in the natural world, and how they give rise to each other in turn."
This sounds like the perfect description of the male-female relationship. Becca and her beau Tim totally understood when I described the nature of this photoshoot to them and volunteered to help me pull it off.
Mike, I hope that this capture of Yin & Yang meets your requirements.
p.s. Subtitle #2 was spoken by a young wife as she lovingly described her husband of five years on their anniversary.
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
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This is the idol of Lord Bhairav at makeshift temple at Juhu Beach ..there are other Hindu gods too but Kali is next to him on the makeshift podium..
.http://en.wikipedia.org/wiki/Kali
Kali redirects here. See Kali (disambiguation) for other uses.
Not to be confused with Kali (demon), the personification of Kali Yuga
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Kali
A painting of Kali in the famous Daksinakali pose
Devanagari: काली
Affiliation: Devi , Mahavidya , Matrika
Abode: Cremation grounds
Mantra: Om Krīm Kālyai namaḥ ,
Om Kapālinaye Namah
Weapon: Sword
Consort: Shiva
Mount: Jackal
Kali (Sanskrit Kālī काली) is a goddess with a long and complex history in Hinduism. Although sometimes presented as dark and violent, her earliest incarnation as a figure of annihilation still has some influence, while more complex Tantric beliefs sometimes extend her role so far as to be the Ultimate Reality (Brahman) and Source of Being. Finally, the comparatively recent devotional movement largely conceives of Kali as a straightforwardly benevolent mother-goddess. Therefore, as with her association with the Deva (god) Shiva, Kali is associated with many Devis (goddesses) - Durga, Bhadrakali, Bhavani, Sati, Rudrani, Parvati, Chinnamasta, Chamunda, Kamakshi or kamakhya, Uma, Meenakshi, Himavanti, Kumari and Tara. These names, if repeated, are believed to give special power to the worshipper.
Kālī is the feminine of kāla "black, dark coloured" (per Panini 4.1.42). It appears as the name of a form of Durga in Mahabharata 4.195, and as the name of an evil female spirit in Harivamsa 11552.
The homonymous kāla "appointed time", which depending on context can mean "death", is distinct from kāla "black", but became associated through popular etymology. The association is seen in a passage from the Mahābhārata, depicting a female figure who carries away the spirits of slain warriors and animals. She is called kālarātri (which Thomas Coburn, a historian of Sanskrit Goddess literature, translates as "night of death") and also kālī (which, as Coburn notes, can be read here either as a proper name or as a description "the black one").[1]
Kali's association with blackness stands in contrast to her consort, Shiva, whose body is covered by the white ashes of the cremation ground (Sanskrit: śmaśāna) in which he meditates, and with which Kali is also associated, as śmaśāna-kālī.
[edit] Origin
Kali appears in the Mundaka Upanishad (section 1, chapter 2, verse 4) not explicitly as a goddess, but as the black tongue of the seven flickering tongues of Agni, the Hindu god of fire. [2]However, the prototype of the figure now known as Kali appears in the Rig Veda, in the form of a goddess named Raatri. Raatri is considered to be the prototype of both Durga and Kali.
In the Sangam era, circa 200BCE-200CE, of Tamilakam, a Kali-like bloodthirsty goddess named Kottravai appears in the literature of the period. Like Kali she has dishevelled hair, inspires fear in those who approach her and feasts on battlegrounds littered with the dead. It is quite likely that the fusion of the Sanskrit goddess Raatri and the indigenous Kottravai produced the fearsome goddesses of medieval Hinduism, amongst them Kali being the most prominent. (See also Sanskritisation)
It was the composition of the Puranas in late antiquity that firmly gave Kali a place in the Hindu pantheon. Kali or Kalika is described in the Devi Mahatmya (also known as the Chandi or the Durgasaptasati) from the Markandeya Purana, circa 300-600CE, where she is said to have emanated from the brow of the goddess Durga, a slayer of demons or avidya, during one of the battles between the divine and anti-divine forces. In this context, Kali is considered the 'forceful' form of the great goddess Durga. Another account of the origins of Kali is found in the Matsya Purana, circa 1500CE, which states that she originated as a mountain tribal goddess in the north-central part of India, in the region of Mount Kalanjara (now known as Kalinjar). However this account is disputed because the legend was of later origin.
The Kalika Purana a work of late ninth or early tenth century, is one of the Upapuranas. The Kalika Purana mainly describes different manifestations of the Goddess, gives their iconographic details, mounts, and weapons. It also provides ritual procedures of worshipping Kalika.
[edit] Kali in Tantra Yoga
Mahakali YantraGoddesses play an important role in the study and practice of Tantra Yoga, and are affirmed to be as central to discerning the nature of reality as the male deities are. Although Parvati is often said to be the recipient and student of Shiva's wisdom in the form of Tantras, it is Kali who seems to dominate much of the Tantric iconography, texts, and rituals.[3] In many sources Kali is praised as the highest reality or greatest of all deities. The Nirvnana-tantra says the gods Brahma, Vishnu, and Shiva all arise from her like bubbles in the sea, ceaslessly arising and passing away, leaving their original source unchanged. The Niruttara-tantra and the Picchila-tantra declare all of Kali's mantras to be the greatest and the Yogini-tantra , Kamakhya-tantra and the Niruttara-tantra all proclaim Kali vidyas (manifestations of Mahadevi, or "divinity itself"). They declare her to be an essence of her own form (svarupa) of the Mahadevi.[4]
In the Mahanirvana-tantra, Kali is one of the epithets for the primordial sakti, and in one passage Shiva praises her:
At the dissolution of things, it is Kala [Time] Who will devour all, and by reason of this He is called Mahakala [an epithet of Lord Shiva], and since Thou devourest Mahakala Himself, it is Thou who art the Supreme Primordial Kalika. Because Thou devourest Kala, Thou art Kali, the original form of all things, and because Thou art the Origin of and devourest all things Thou art called the Adya [primordial Kali. Resuming after Dissolution Thine own form, dark and formless, Thou alone remainest as One ineffable and inconceivable. Though having a form, yet art Thou formless; though Thyself without beginning, multiform by the power of Maya, Thou art the Beginning of all, Creatrix, Protectress, and Destructress that Thou art.[5]
The figure of Kali conveys death, destruction, fear, and the consuming aspects of reality. As such, she is also a "forbidden thing", or even death itself. In the Pancatattva ritual, the sadhaka boldly seeks to confront Kali, and thereby assimilates and transforms her into a vehicle of salvation.[6] This is clear in the work of the Karpuradi-stotra, a short praise to Kali describing the Panacatattva ritual unto her, performed on cremation grounds. (Samahana-sadhana)
He, O Mahakali who in the cremation-ground, naked, and with dishevelled hair, intently meditates upon Thee and recites Thy mantra, and with each recitation makes offering to Thee of a thousand Akanda flowers with seed, becomes without any effort a Lord of the earth. 0 Kali, whoever on Tuesday at midnight, having uttered Thy mantra, makes offering even but once with devotion to Thee of a hair of his Sakti [his female companion] in the cremation-ground, becomes a great poet, a Lord of the earth, and ever goes mounted upon an elephant.[7]
The Karpuradi-stotra clearly indicates that Kali is more than a terrible, vicious, slayer of demons who serves Durga or Shiva. Here, she is identified as the supreme mistress of the universe, associated with the five elements. In union with Lord Shiva, who is said to be her spouse, she creates and destroys worlds. Her appearance also takes a different turn, befitting her role as ruler of the world and object of meditation.[8] In contrast to her terrible aspects, she takes on hints of a more benign dimension. She is described as young and beautiful, has a gentle smile, and makes gestures with her two right hands to dispel any fear and offer boons. The more positive features exposed offer the distillation of divine wrath into a goddess of salvation, who rids the sadhaka of fear. Here, Kali appears as a symbol of triumph over death.[9]
[edit] Kali in Bengali tradition
Kali is also central figure in late medieval Bengali devotional literature, with such devotees as Ramprasad Sen (1718-75). With the exception of being associated with Parvati as Shiva's consort, Kali is rarely pictured in Hindu mythology and iconography as a motherly figure until Bengali devotion beginning in the early eighteenth century. Even in Bengali tradition her appearance and habits change little, if at all.[10]
The Tantric approach to Kali is to display courage by confronting her on cremation grounds in the dead of night, despite her terrible appearance. In contrast, the Bengali devotee appropriates Kali's teachings, adopting the attitude of a child. In both cases, the goal of the devotee is to become reconciled with death and to learn acceptance of the way things are. These themes are well addressed in Ramprasad's work.[11]
Ramprasad comments in many of his other songs that Kali is indifferent to his wellbeing, causes him to suffer, brings his worldly desires to nothing and his worldly goods to ruin. He also states that she does not behave like a mother should and that she ignores his pleas:
Can mercy be found in the heart of her who was born of the stone? [a reference to Kali as the daughter of Himalaya]
Were she not merciless, would she kick the breast of her lord?
Men call you merciful, but there is no trace of mercy in you. Mother.
You have cut off the headset the children of others, and these you wear as a garland around your neck.
It matters not how much I call you "Mother, Mother." You hear me, but you will not listen.[12]
To be a child of Kali, Ramprasad asserts, is to be denied of earthly delights and pleasures. Kali is said to not give what is expected. To the devotee, it is perhaps her very refusal to do so that enables her devotees to reflect on dimensions of themselves and of reality that go beyond the material world. [13][14]
[edit] Mythology
[edit] Slayer of Raktabija
"Kali Triumphant on The Battle Feild," Punjab, circa 1800-20CE)In Kali's most famous myth, Durga and her assistants, Matrikas, wound the demon Raktabija, in various ways and with a variety of weapons, in an attempt to destroy him. They soon find that they have worsened the situation, as for every drop of blood that is spilt from Raktabija the demon reproduces a copy of himself. The battlefield becomes increasingly filled with his duplicates.[15] Durga, in dire need of help, summons Kali to combat the demons.
The Devi Mahatmyam describes:
Out of the surface of her(Durga's) forehead, fierce with frown, issued suddenly Kali of terrible countenance, armed with a sword and noose. Bearing the strange khatvanga (skull-topped staff ) , decorated with a garland of skulls, clad in a tiger’s skin, very appalling owing to her emaciated flesh, with gaping mouth, fearful with her tongue lolling out, having deep reddish eyes, filling the regions of the sky with her roars, falling upon impetuously and slaughtering the great asuras in that army, she devoured those hordes of the foes of the devas.[16]
Kali destroys Raktabija by sucking the blood from his body and putting the many Raktabija duplicates in her gaping mouth. Pleased with her victory, Kali then dances on the field of battle, stepping on the corpses of the slain. Her consort Shiva lies among the dead beneath her feet, a representation of Kali commonly seen in iconography, the Daksinakali pose.[17]
In Devi Mahatmya version of this story, Kali is also described as an Matrika and as a Shakti or power of Devi. She is given the epithet Cāṃuṇḍā (Chamunda) i.e the slayer of demons Chanda and Munda. [18] Chamunda is very often identified with Kali and is very much like in her appearance and habit.[19]
[edit] Daksinakali
In her most famous pose as Daksinakali, it is said that Kali, becoming drunk on the blood of her victims on the battlefield, dances with destructive frenzy. In her fury she fails to see the body of her husband Shiva who lies among the corpses on the battlefield.[20] Ultimately the cries of Shiva attract Kali's attention, calming her fury. As a sign of her shame at having disrespected her husband in such a fashion, Kali sticks out her tongue. However, some sources state that this interpretation is a later version of the symbolism of the tongue: in tantric contexts, the tongue is seen to denote the element (guna) of rajas (energy and action) controlled by sattva, spiritual and godly qualities. [21]
One South Indian tradition tells of a dance contest between Shiva and Kali. After defeating the two demons Sumbha and Nisumbha, Kali takes residence in a forest. With fierce companions she terrorizes the surrounding area. One of Shiva's devotees becomes distracted while doing austerities and asks Shiva to rid the forest of the destructive goddess. When Shiva arrives, Kali threatens him, claiming the territory as her own. Shiva challenges her to a dance contest, and defeats her when she is unable to perform the energetic Tandava dance. Although here Kali is defeated, and is forced to control her disruptive habits, we find very few images or other myths depicting her in such manner.[22]
Bhadrakali (A gentle form of Kali), circa 1675 Painting; Made in: India, Himachal Pradesh, Basohli , now placed in LACMA Museum(M.72.53.7)
[edit] Maternal Kali
Another myth depicts the infant Shiva calming Kali, instead. In this similar story, Kali again defeated her enemies on the battlefield and began to dance out of control, drunk on the blood of the slain. To calm her down and to protect the stability of the world, Shiva is sent to the battlefield, as an infant, crying aloud. Seeing the child's distress, Kali ceases dancing to take care of the helpless infant. She picks him up, kisses his head, and proceeds to breast feed the infant Shiva.[23] This myth depicts Kali in her benevolent, maternal aspect something that is revered in Hinduism, but not often recognized in the West.
[edit] Mahakali
Mahakali (Sanskrit: Mahākālī, Devanagari: महाकाली), literally translated as Great Kali, is a Hindu Goddess, considered by some to be the consort of Shiva, and by others as the basis of Reality (see below). Mahakali in Sanskrit is etymologically the feminized variant of Mahakala or Great Time (which is interpreted also as Death), an epithet of the God Shiva in Hinduism but also the name of a Dharmapala or wrathful deity in Vajrayana Buddhism. Mahakali can also simply be used as an honorific of the Goddess Kali, signifying her greatness by the prefix "Mahā-".
[edit] Iconography
Statue from Dakshineswar Kali Temple, West Bengal, India; along with her Yantra.Kali is portrayed mostly in two forms: the popular four-armed form and the ten-armed Mahakali form. In both the forms, she is described as being black in color but is most often depicted as blue in popular Indian art. Her eyes are described as red with intoxication and in absolute rage, Her hair is shown disheveled, small fangs sometimes protrude out of Her mouth and Her tongue is lolling. She is often shown naked or just wearing a skirt made of human arms and a garland of human heads. She is also accompanied by serpents and a jackal while standing on a seemingly dead Shiva, usually right foot forward to symbolize the more popular Dakshinamarga or right-handed path, as opposed to the more infamous and transgressive Vamamarga or left-handed path. [24]
The Kalika Purana describes Kali as possessing a soothing dark complexion, as perfectly beautiful, riding a lion, four armed, holding a sword and blue lotuses, her hair unrestrained, body firm and youthful.[25]
In spite of her seemingly terrible form, Kali is often considered the kindest and most loving of all the Hindu goddesses, as she is regarded by her devotees as the Mother of the whole Universe. And, because of her terrible form she is also often seen as a great protector. When the Bengali saint Ramakrishna once asked a devotee why one would prefer to worship Mother over him, this devotee rhetorically replied, “Maharaj, when they are in trouble your devotees come running to you. But, where do you run when you are in trouble?”[26]
Throughout her history artists the world over have portrayed Kali in a myriad of poses and settings, some of which stray far from the popular description, and are sometimes even graphically sexual in nature. Given the popularity of this Goddess, artists everywhere will continue to explore the magnificence of Kali’s iconography. This is clear in the work of such contemporary artists as Charles Wish, and Tyeb Mehta, who sometimes take great liberties with the traditional, accepted symbolism, but still demonstrate a true reverence for the Shakta sect.
[edit] Popular form of Kali
Classic depictions of Kali share several features, as follows:
Kali's most common four armed iconographic image shows each hand carrying variously a sword, a trishul (trident), a severed head and a bowl or skull-cup (kapala) catching the blood of the severed head.
Two of these hands (usually the left) are holding a sword and a severed head. The Sword signifies Divine Knowledge and the Human Head signifies human Ego which much be slain by Divine Knowledge in order to attain Moksha. The other two hands (usually the right) are in the abhaya and varada mudras or blessings, which means her initiated devotees (or anyone worshiping her with a true heart) will be saved as she will guide them here and in the hereafter.[27]
She has a garland consisting of human heads, variously enumerated at 108 (an auspicious number in Hinduism and the number of countable beads on a Japa Mala or rosary for repetition of Mantras) or 51, which represents Varnamala or the Garland of letters of the Sanskrit alphabet, Devanagari. Hindus believe Sanskrit is a language of dynamism, and each of these letters represents a form of energy, or a form of Kali. Therefore she is generally seen as the mother of language, and all mantras.[28]
She is often depicted naked which symbolizes her being beyond the covering of Maya since she is pure (nirguna) being-consciousness-bliss and far above prakriti. She is shown as very dark as she is brahman in its supreme unmanifest state. She has no permanent qualities -- she will continue to exist even when the universe ends. It is therefore believed that the concepts of color, light, good, bad do not apply to her -- she is the pure, un-manifested energy, the Adi-shakti.[29]
[edit] Mahakali Form
Ekamukhi or "One-Faced" Murti of Mahakali displaying ten hands holding the signifiers of various DevasHer ten headed (dasamukhi) image is known as Dasa Mahavidya Mahakali, and in this form She is said to represent the ten Mahavidyas or "Great Wisdom (Goddesse)s". She is depicted in this form as having ten heads, ten arms, and ten legs but otherwise usually conforms to the four armed icon in other respects. Each of her ten hands is carrying a various implement which vary in different accounts, but each of these represent the power of one of the Devas or Hindu Gods and are often the identifying weapon or ritual item of a given Deva. The implication is that Mahakali subsumes and is responsible for the powers that these deities possess and this is in line with the interpretation that Mahakali is identical with Brahman. While not displaying ten heads, an "ekamukhi" or one headed image may be displayed with ten arms, signifying the same concept: the powers of the various Gods come only through Her grace.
[edit] Shiva in Kali Iconography
Kali in Traditional Form, standing on Shiva's chest.In both these images she is shown standing on the prone, inert or dead body of Shiva. There is a mythological story for the reason behind her standing on what appears to be Shiva’s corpse, which translates as follows:
Once Kali had destroyed all the demons in battle, she began a terrific dance out of the sheer joy of victory. All the worlds or lokas began to tremble and sway under the impact of her dance. So, at the request of all the Gods, Shiva himself asked her to desist from this behavior. However, she was too intoxicated to listen. Hence, Shiva lay like a corpse among the slain demons in order to absorb the shock of the dance into himself. When Kali eventually stepped upon her husband she realized her mistake and bit her tongue in shame.[30]
However, the symbolism of the above mentioned theological perspective is often seen as antiquated and misogynistic. The more thoughtful (and Tantric) interpretation of Kali standing on top of her husband is as follows:
The Shiv tattava (Divine Consciousness as Shiva) is inactive, while the Shakti tattava (Divine Energy as Kali) is active. Shiva, or Mahadeva represents Brahman, the Absolute pure consciousness which is beyond all names, forms and activities. Kali, on the other hand, represents the potential (and manifested) energy responsible for all names, forms and activities. She is his Shakti, or creative power, and is seen as the substance behind the entire content of all consciousness. She can never exist apart from Shiva or act independently of him, i.e., Shakti, all the matter/energy of the universe, is not distinct from Shiva, or Brahman, but is rather the dynamic power of Brahman.[31]
While this is an advanced concept in monistic Shaktism, it also agrees with the Nondual Trika philosophy of Kashmir, popularly known as Kashmir Shaivism and associated most famously with Abhinavagupta. There is a colloquial saying that "Shiva without Shakti is Shava" which means that without the power of action (Shakti) that is Mahakali (represented as the short "i" in Devanagari) Shiva (or consciousness itself) is inactive; Shava means corpse in Sanskrit and the play on words is that all Sanskrit consonants are assumed to be followed by a short letter "a" unless otherwise noted. The short letter "i" represents the female power or Shakti that activates Creation. This is often the explanation for why She is standing on Shiva, who is either Her husband and complement in Shaktism or the Supreme Godhead in Shaivism.
To properly understand this complex Tantric symbolism it is important to remember that the meaning behind Shiva and Kali does not stray from the non-dualistic parlance of Shankara or the Upanisads. According to both the Mahanirvana and Kularnava Tantras, there are two distinct ways of perceiving the same absolute reality. The first is a transcendental plane which is often described as static, yet infinite. It is here that there is no matter, there is no universe and only consciousness exists. This form of reality is known as Shiva, the absolute Sat-Chit-Ananda -- existence, knowledge and bliss. The second is an active plane, an immanent plane, the plane of matter, of Maya, i.e., where the illusion of space-time and the appearance of an actual universe does exist. This form of reality is known as Kali or Shakti, and (in its entirety) is still specified as the same Absolute Sat-Chit-Ananda. It is here in this second plane that the universe (as we commonly know it) is experienced and is described by the Tantric seer as the play of Shakti, or God as Mother Kali.[32]
Kali and Bhairava(the terrible form of Shiva) in Union, 18th century, NepalFrom a Tantric perspective, when one meditates on reality at rest, as absolute pure consciousness (without the activities of creation, preservation or dissolution) one refers to this as Shiva or Brahman. When one meditates on reality as dynamic and creative, as the Absolute content of pure consciousness (with all the activities of creation, preservation or dissolution) one refers to it as Kali or Shakti. However, in either case the yogini or yogi is interested in one and the same reality -- the only difference being in name and fluctuating aspects of appearance. It is this which is generally accepted as the meaning of Kali standing on the chest of Shiva.[33]
Although there is often controversy surrounding the images of divine copulation, the general consensus is benign and free from any carnal impurities in its substance. In Tantra the human body is a symbol for the microcosm of the universe; therefore sexual process is responsible for the creation of the world. Although theoretically Shiva and Kali (or Shakti) are inseparable, like fire and its power to burn, in the case of creation they are often seen as having separate roles. With Shiva as male and Kali as female it is only by their union that creation may transpire. This reminds us of the prakrti and purusa doctrine of Samkhya wherein vimarsa-prakasa has no practical value, just as without prakrti, purusa is quite inactive. This (once again) stresses the interdependencies of Shiva and Shakti and the vitality of their union. [34]
[edit] Development
In the later traditions, Kali has become inextricably linked with Shiva. The unleashed form of Kali often becomes wild and uncontrollable, and only Shiva is able to tame her. This is both because she is often a transformed version of one of his consorts and because he is able to match her wildness. His methods vary from challenging her to the wild tandava dance and outdoing her, to appearing as a crying infant and appealing to her maternal instincts. While Shiva is said to be able to tame her, the iconography often presents her dancing on his fallen body, and there are accounts of the two of them dancing together, and driving each other to such wildness that the world comes close to unravelling.
Shiva's involvement with Tantra and Kali's dark nature have led to her becoming an important Tantric figure. To the Tantric worshippers, it was essential to face her Curse, the terror of death, as willingly as they accepted Blessings from her beautiful, nurturing, maternal aspect. For them, wisdom meant learning that no coin has only one side: as death cannot exist without life, so life cannot exist without death. Kali's role sometimes grew beyond that of a chaos -- which could be confronted -- to that of one who could bring wisdom, and she is given great metaphysical significance by some Tantric texts. The Nirvāna-tantra clearly presents her uncontrolled nature as the Ultimate Reality, claiming that the trimurti of Brahma, Visnu and Rudra arise and disappear from her like bubbles from the sea. Although this is an extreme case, the Yogini-tantra, Kamakhya-tantra and the Niruttara-tantra declare her the svarupa (own-being) of the Mahadevi (the great Goddess, who is in this case seen as the combination of all devis).
The final stage of development is the worshipping of Kali as the Great Mother, devoid of her usual violence. This practice is a break from the more traditional depictions. The pioneers of this tradition are the 18th century Shakta poets such as Ramprasad Sen, who show an awareness of Kali's ambivalent nature. Ramakrishna, the 19th century, Bengali saint, was also a great devotee of Kali; the western popularity of whom may have contributed to the more modern, equivocal interpretations of this Goddess. Rachel McDermott's work, however, suggests that for the common, modern worshipper, Kali is not seen as fearful, and only those educated in old traditions see her as having a wrathful component. Some credit to the development of Devi must also be given to Samkhya. Commonly referred to as the Devi of delusion, Mahamaya, acting in the confines of (but not being bound by) the nature of the three gunas, takes three forms: Maha-Kali, Maha-Lakshmi and Maha-Saraswati, being her tamas-ika, rajas-ika and sattva-ika forms. In this sense, Kali is simply part of a larger whole.
Like Sir John Woodroffe and Georg Feuerstein, many Tantric scholars (as well as sincere practitioners) agree that, no matter how propitious or appalling you describe them, Shiva and Devi are simply recognizable symbols for everyday, abstract (yet tangible) concepts such as perception, knowledge, space-time, causation and the process of liberating oneself from the confines of such things. Shiva, symbolizing pure, absolute consciousness, and Devi, symbolizing the entire content of that consciousness, are ultimately one and the same -- totality incarnate, a micro-macro-cosmic amalgamation of all subjects, all objects and all phenomenal relations between the "two." Like man and woman who both share many common, human traits yet at the same time they are still different and, therefore, may also be seen as complementary.[35]
Sadhakas and sadhikas (of all generations) prescribe various benign and horrific qualities to Devi simply out of practicality. They do this so they may have a variety of symbols to choose from, symbols which they can identify and relate with from the perspective of their own, ever-changing time, place and personal level of unfolding. Just like modern chemists or physicists use a variety of molecular and atomic models to describe what is unperceivable through rudimentary, sensory input, the scientists of ontology and epistemology must do the same. One of the underlying distinctions of Tantra (in comparison to other religions) is that it allows the devotee the liberty to choose (from a vast array of complementary symbols and rhetoric) that which suits one’s evolving needs and tastes. From an aesthetic standpoint, nothing is interdict and nothing is orthodox. In this sense, the projection of some of Devi’s more gentle qualities onto Kali is not sacrilege and the development of Kali really lies in the practitioner, not the murthi.
actually the picture is of bhairav.. goddess kali is next to him
Yin Yang is a Chinese symbol illustrating "how polar or seemingly contrary forces are interconnected and interdependent in the natural world, and how they give rise to each other in turn." This simple shape of mirrored inverted images is represents many concepts and a variety of religious, and cultural practices including Taoism, the I Ching, Tai Chi and more. Continue reading on Wikipedia.
Yin, Yang, slow, fast, soft, hard, yielding, solid, diffuse, focused, cold, hot, wet, dry, passive, aggressive, water, fire, earth, sky, moon, sun, femininity, masculinity, nighttime, daytime.
The artist/event can’t exist without public. They are interdependent. This photo is part of a series about the counterpart of the artist/events: “Spectators’.
This one's for Jon DeBoer who inspired me to find this location after seeing some of his images of this abandoned structure. I could spend hours here and am looking forward to returning to try out some daytime long exposures.
Date: September 2021
Medium: Digital Photomontage and Digital Photographs
Location: Santa Cruz, CA
Dimensions: 15” x 30”
© 2021 Tony DeVarco
Credit: Left Panel- Totenschädel (Skull), 1521 by Albrecht Durer. Downloaded from Wikiart at www.wikiart.org/en/albrecht-durer/skull
What is Interdependent Origination? By Francesca Fremantle www.lionsroar.com/dharma-dictionary-interdependent-origin...
Lamellae, Singapore
Ahtehha, 2019
A shelf and display case for research (printed/3d pritned) in the Digital Manufacturing and Design lab.
A multi-agent approach to fabrication. Adapting a lamella system assembly to freeform geometry, every element has a reciprocal relationship with the neighboring pieces creating a complex, interdependent geometry. This is heightened by using 5-axis CNC swarf cutting to maintain surface continuity at joints and integrating all mortise and tenon connections. Each element is modelled as an instance of an agent that determines positioning, relationships with adjacent members, and geometric requirements. The precision of the geometry and CNC fabrication allows for direct assembly that holds by friction-fit alone.
1mm aluminum inserts are added to provide horizontal display surfaces and as a redundant system for shear forces. The rear surface is planarized (with quad preference) and fastening tabs are autmatically placed to adapt to each unique joint, avoiding overlaps.
Explore Jun 4, 2011 #182
The Atala butterfly is strange to photograph. The colored areas are vague at the margins so the color looks like it has been dusted on a bit carelessly. But look at its marvelous tones... deep velvety blue, bright sky blue and a brilliant red orange! It is very fast moving so getting a shot at all is always a thrill! Usually looks like a vibrant patch of astounding flying color and it's gone.
Interdependencies in nature once again. This marvelous creature owes its life to the Florida Coontie which was almost wiped out after being the money crop of the first Florida pioneers. Without the Coontie, this beauty will be gone.
The short, woody stem and rootstock of the coontie grows almost completely underground and produces a terminal crown of stiff, evergreen, pinnate leaves up to 3 feet long. The brown, fleshy, erect, female or seed-bearing cones are pendent when mature. Coontie plants contain a natural toxin, which atala larvae accumulate in their bodies and use to repel birds. Without coontie, adult atalas have no place to lay eggs. No eggs means no new generations. .
Wild coonties’ demise began with starch: Long before Europeans arrived in Florida, Native Americans used coontie as a source of starch. Coontie, in fact, is a Seminole word that means “bread” or “white root” because the roots can be made into flour.
From "The Forgotten Frontier: Florida Through the Lens of Ralph Middleton Munroe" by Arva Moore Parks: 'Behind the hammock land the pine and palmetto country seemed to go on forever. Sending roots into the crevices of stone, the tall pine and its companions, the bushy palmetto and the fernlike comptie (Zamia), thrived in what seemed like solid rock. Althought not as glamorous as the hammock, the pineland was the backbone of the land. The heart of the pine became the foundation of the pioneer home; the palmetto, for thatch, became the roof; and the starch made from the root of the comptie filled the pionerer's stomach."
Cootie is sporadic in pinelands and hammocks throughout nearly all peninsular Florida and the Keys. In an effort to preserve the Atala, the coontie is being used increasingly in landscaping. Here in Miami, it is growing at Arch Creek East Environmental Preserve.
Arch Creek was an early Tequesta Indian settlement here in North Miami. Arch Creek is spanned by a natural limestone bridge. Early photographs of Miami show the bridge in all its beauty. Compromised now by encroaching housing and roadways.
The Tequesta Indians thrived in Arch Creek and the surrounding area. There was an oak hammock near the creek which provided shade as well as edible plants, nuts and berries. Biscayne Bay, less than a half mile away, was a prime food source for the Tequestas. There they caught shellfish, shark, manatee and turtle. North of the hammock were pine flatlands, which sheltered the all-important coontie plant (Zamia integrifolia), whose roots the Indians ground to make an edible starch product.
Tequesta habitation sites characteristically have midden areas or Indian garbage dumps. The gradual decomposition of refuse, including plant material and animal bones, produces a rich black soil. Many artifacts have been preserved in the soil, and archaeologists have uncovered many of them, such as bone points, shell tools and pottery shards. During their centuries of occupation (from c. 400 A.D. to c. 1200 A.D.), the Arch Creek Tequestas had what appears to be a fairly comfortable lifestyle, supported by the abundant natural resources at the site.
Around 1858 two ambitious pioneers used the creek and its natural bridge as a site for a coontie starch mill. These early entrepreneurs learned how to clean the poisonous roots and dammed up the waterway under the bridge diverting the flow through a sluice they carved out of a solid limestone bank. The water turned a wooden wheel attached to a nail-studded grinder, which mashed the cootie roots into a paste-like pulp. The resulting starch was then soaked and strained to remove any remaining poison. Laid out in wooden racks, the starch dried quickly and the sun bleached it white. In the early 1900s, several commercial factories in South Florida processed coontie roots for the manufacture of arrowroot biscuits. But coontie starch was not as successful as the pioneers thought, and the mill was abandoned several years later. The water sluice was filled in and paved over, and was not discovered until archaeologists excavated it in 1972.
Atala Eumaeus
Fairchild Tropical Botanic Garden, Miami FL
The artist/event can’t exist without public. They are interdependent. This photo is part of a series about the counterpart of the artist/events: “Spectators’.
Covering Letter Jitish Kallat 2012
In Revolution
Artist Jitish Kallat embraces an interdependent notion of time as his work weaves together contexts and events into a constellation that is neither solely of the past, nor of the future, but which finds repeating intersections in the present.
"This is not simply an artwork about Gandhi and Hitler, or divine and devil, but from one life view to another."
Henry David Thoreau in Civil Disobedience, describes the revolutionary as one who emerges "in a counter-friction to stop the machine." In Covering Letter, Gandhi's words repeat like a looped scroll, calling to the revolutionaries of today--the carriers of a new justice paradigm--to disrupt our circuitry.
( from the notes Philadelphia Museum of Art )
both mother and father give birth to being parents
at the same time as their children are born
parents and children are interdependent
half their chromosomes come from their father
the other half from their mother
so there is a mother and father within each cell of their children
even after a children’s parents no longer have a body
one can say, “hello mother, hello father”
while looking deep within
if their children live their lives well
with presence and mindfulness
with that thought in mind
surely their parents will benefit
even after their parent’s bodies are gone
they are a part of their children
paraphrased from talks I heard by Thich Nhat Hanh
~ ~ ~
“Interbeing
The Sun has entered me.
The Sun has entered me together with the cloud and the river.
I myself have entered the Sun with the cloud and the river.
There has not been a moment when we do not interpenetrate.
But before the Sun entered me, the Sun was in me –
also the cloud and the river.
Before I entered the river, I was already in it.
There has not been a moment when we have not inter-been.
Therefore you know that as long as you continue to breathe,
I continue to be in you.”
—Thich Nhat Hanh, from "Call me by my true names: the collected poems of Thich Nhat Hanh"
Spaceisneat made a video using this poem, and background music by Enya:
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
Lamellae, Singapore
Ahtehha, 2019
A shelf and display case for research (printed/3d pritned) in the Digital Manufacturing and Design lab.
A multi-agent approach to fabrication. Adapting a lamella system assembly to freeform geometry, every element has a reciprocal relationship with the neighboring pieces creating a complex, interdependent geometry. This is heightened by using 5-axis CNC swarf cutting to maintain surface continuity at joints and integrating all mortise and tenon connections. Each element is modelled as an instance of an agent that determines positioning, relationships with adjacent members, and geometric requirements. The precision of the geometry and CNC fabrication allows for direct assembly that holds by friction-fit alone.