View allAll Photos Tagged implied
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.
From a workshop-style group shoot with plenty of snakes and models!
Comments and critique of the photos welcome.
Model is Brandi (IG: @treatherwell)
Model - Chantelle @ Base Models
Makeup - Katherine Axford
Photographer - Simon Ackerman
© Simon Ackerman 2012
7 star strategies for your child's future
How can you put a price on the expression of pure bliss on your four-year-old's face
as she enjoys an ice-cream? When your 17-year-old whoops on hearing the news that
he has secured admission to his dream college, would your brain tick away at the
amount of money this is going to cost you?
These are non-questions to any parent. Parental love is unconditional and largely
unaccountable. It's heartless and clinical to count your child as a cost centre, and we
are not suggesting you do that.
Understanding expenses does not imply condemning them. On the contrary, it is only a
first step towards gaining an advantage over them. In fact, if you do manage to chip
away at the warm, fuzzy feeling of pride and accomplishment and examine the costs
of raising a child, you would be able to do a far better job of being the provider.
The dichotomy of spending on your children is a conflict between the present and the
future. Should you cave in and buy the Rs 25,000 Playstation 3 that your son has
been nagging you for? Will it come from the money you have been saving for his
graduation? Will that Barbie-themed Rs 50,000 party you threw on your daughter's
birthday be the reason she will have to do her hotel management in Goa instead of
Geneva? The only way to solve these dilemmas is to plan ahead and start investing.
Now.
Two big-ticket costs that all parents have to provide for fall under the heads
education and marriage. Post-graduate education is expensive, and in this globalised
world, if you want to give your child the advantage of an international education,
multiply the cost by 10 times, often even more. A grand celebration to mark your
child's wedding is a great Indian dream and something that all parents would like to
put some money away for.
1. Second baby
Most couples can afford one child and want to do the best for him or her. As financial
decisions go, the second child is usually one that swings the balances. The thought of
having to keep away double the amount of what you need for a child can be daunting.
Often, when the kids are young, one plus one does not add up to two - you could
re-use and recycle and keep your expenses slightly lower. But, as they grow older,
two children can be a real strain on finances. Guitar lessons for one, football coaching
for the other, science tuitions for one and mathematics for the other can add up to a
tidy sum every month.
A second child had always featured in Jayant Bhadauria and Kamalika Nandi's life
plans. It's just that they did not really have the time to have one. Jayant works in a
multinational software company in Mumbai and Kamalika looks after marketing for an
outsourcing company.
Between work, their travelling schedules and looking after Kamini, their four-year-old
daughter, the second child remained something to be done sometime in the future.
Which was why, in September, when Kamalika discovered she was pregnant, for a
minute she didn't know whether to be happy or sad.
"Of course, money was not the first thing I thought about," says Kamalika. "Once the
news sank in, I did realise that we would have to start looking at our expenses. So
far, if I have seen something and liked it, I have ended up buying it if I felt the price
was fair. Now, I feel, there would be a little bit of a compromise there. I do want the
best for my kids, but that does not necessarily mean the most expensive."
7 star strategies for your child's future
The baby is due in May and, for now, they are figuring out the expenses related to
having him - delivery and hospitalisation are just two of the heads. A normal delivery
in a reasonably good hospital costs about Rs 35,000. If there are complications, the
fee could be substantially higher. Kamalika reckons their monthly expenditure would
increase by at least Rs 7,000 for the first year of the new baby.
A substantial portion of the large expenses they incurred for Kamini would not have to
be repeated. Expensive baby paraphernalia like the cot, stroller, rocker and high chair
can be reused for the second baby.
Jayant has a couple of insurance policies. The rest of his investments are all in equity.
He has an employee stock option in his company. Besides this, he has also opted to
buy the equity of his employer, listed in the US, with a certain percentage of his
salary every month.
The rest of his portfolio is in various Indian companies. While equity investment is the
ideal route to create wealth for his young family, Jayant should also look at
diversifying his portfolio. A major chunk of his money is invested in one stock - that of
his employer.
Jayant is also evaluating a couple of child policies from insurance companies. He
wants to use these as vehicles to save for his kids' higher education and marriages.
He is confident that as the expenses of the kids increase, so will his wife's and his
own salaries and that there will not be a situation of having to face a financial crunch.
Kamalika plans to return to work once her maternity benefits expire. When she was
expecting Kamini, she had given up her job and stayed home till her daughter turned
two. "I will try and enjoy the baby more since this is the last one I will have, but it
might be difficult because I plan to go back to work," she says.
"My career has suffered because of the break I took the last time and I don't want to
do it again. But, my company is employee-friendly and I feel that I would be able to
get leave in case I need to spend more time at home."
For now, they are not thinking about late night feeds and diaper changes. They have
chosen to focus instead on Tahitian weddings and exotic holidays for their kids.
2. Nascent dreams
When Simran Kumar thinks about her kids' future, she is not worried about which
school they will secure admission in or how big a wedding they will have. But, as a
modern, aware mother, she does get anxious about the world they will occupy, what
with environmental pollution, global warming and the rest. "I am concerned about
security issues, about violence against women, childhood respiratory diseases from
living in a polluted and crowded city," she says.
Simran and her husband, Zafar Baig, have two children under the age of two -
daughter Ananya is 22 months, and son Vivan is four months old.
Simran is an anchor for a television channel and Zafar works for an export house. With
two well paying jobs, they have not been worried about spending on the luxuries, so
far. But as their young family grows, they want to make sure they get started on
laying the foundation for a sound financial future.
"Now, we do not spend carelessly and have cut out a little bit of our frivolous
expenses. I want the best for my kids," she says.
One of the dreams Simran and Zafar have for their children is to offer them an
opportunity to follow in their footsteps and study abroad. "We are not very
money-savvy, but now want to invest in our kids' future. We do not really know
where to start," says Simran.
7 star strategies for your child's future
They have, however, opened bank accounts in both kids' names and all the money
they have received as gifts has gone into them. Zafar has bought a couple of
insurance policies and invested a bit directly in equity, as well as in some mutual
funds.
He recently invested Rs 50,000 in HDFC Standard Life's Young Star Plan. Even as they
try and cope with the 'now and here' expenses of a family of four, as well as investing
in their dreams for their kids, Simran and Zafar would also like to buy a house.
They are not alone in wanting to do several things at once. Most couples are in the
early stages of their careers when they start their families. Often, the need to put
away for a rainy day is lost in the euphoria of youth and its maxim of living for the
day.
When the kids come, several priorities tumble out of the financial closet -- a house,
some means of protecting income and insurance against unforeseeable events, buying
things for the baby, hiring someone to help look after them. Often, with this, also
comes a drastic drop in income levels if the mother chooses to stay back home and
look after the kids for a few years.
The key here is in being able to prioritise and not trying to do everything at once. The
important goals of higher education and marriage of children are quite far away and
even putting away a little sum of money starting right away would be enough.
What is key is getting into the discipline of saving, the amounts can be large or small.
As the goals are far away, most investments can be directed into equities. Systematic
investment plans (SIPs) of good funds, with a long-term view, are ideal here.
Short-term expenditure can be rationalised and reduced if there are opportunities.
Simran reckons she spends about Rs 10,000-15,000 a month now on the kids. This
includes diapers (about Rs 500 for a pack of 50), food and household help.
Simran works three days a week, and that leaves her with enough time to spend with
her children. Once they start school, she can go back to working full time. Simran is
optimistic about her future. "It's all there somewhere, I am a positive person in that
sense," she says. "For now, I want to focus on enjoying my babies," she adds.
3. Wonder years
The five years when the child has started school but is not yet in a higher class that
warrants private tuitions is the ramp up stage for the finances of parents. The goals
of higher education and marriage are some distance away, yet well within view.
Even though the primary schooler's ambitions vary widely from day to day, you could
still get a sense of the direction in which he is likely to head. This is the stage where
you could build your savings. If you have SIPs, you could increase the amount you
invest every month.
On the expense side, this is perhaps the easiest stage. You do not have the
heavy-duty everyday requirements of diapers and baby food, nor have you reached
the stage where you have to spend Rs 300 for one hour of mathematics tuition.
School fees, books, birthday parties and expenses on outings and excursions would be
areas of high spends. A birthday party can cost anywhere between Rs 3,000 and Rs
20,000.
In Kolkata, nine-year-old Arkatapa wants to be an archaeologist one day and a
teacher the next. She attends classes on ancient mathematics, Bharatnatyam, singing
and drawing. But her mother, Arpita Roy, feels when it comes to choosing a career,
Arkatapa will pick an academically-oriented one.
7 star strategies for your child's future
Arkatapa's father, Barun Kumar Roy, is an officer in the West Bengal government. His
money mantra is that investments should be made for the short term and loans should
be taken for the long term. He spends 60 per cent of his salary and saves the
remaining 40 per cent.
Barun invests with a three-to-four-year view. His first priority is insurance policies, so
that in case anything happens to him, his family does not suffer financially. He has life
insurance policies and Ulips with accident covers. He also has some investments in
Prudential ICICI Mutual Fund. These are in both equity and debt funds. Child plans do
not attract him, he has not taken any for Arkatapa.
An ideal asset allocation at this stage of your child's life is to have 75 per cent of your
investments in equity. This implies that in the intervening years between 0-4 and
5-10, you move some part of your money from pure equity to balanced or debt funds.
Arpita never wanted a career, she was always keen on staying home and looking after
her family. But her advice to her daughter would be to be self-reliant and have the
financial ability to look after herself.
Arpita finds her joy in her daughter's accomplishments. "When she scores 15 out of 15
in a test, I feel very happy. Even though it is a little silly, I do feel happy," she says.
"My daughter is not a very brilliant student, but she is still young. I am not worried
about her career now, water will flow where it will."
Her husband agrees that it is too early to predict what their daughter will grow up to
be, but he is certain that he must invest in her future. "Whenever she makes her
choice of education or career, it should not get stuck because there is no money for
it," he says emphatically.
"Every moment as a father has been a proud one." His dream for his daughter is that
she grows up to be honest, respectful and a good human being. "Everything else is
extra," he says.
4. Early teenage mayhem
As Rishab Nanda grows tall and lanky, his parents, Manisha and Manish, are beginning
to anticipate the mood swings and door slamming that will start as their
soon-to-be-12-year-old grapples with adolescence. Already, there are arguments and
high drama about pretty much everything -- from walking the dog to going on trips
with friends.
Although Rishab is yet unsure of exactly what he wants to grow up to be, the options
are getting clearer by the day. His parents do not want to get caught on the wrong
foot at the last moment and are now quickly squirrelling away as much money as
possible to fund his dreams.
Rishab's school offers the International Baccalaureate (IB) programme and his parents
expect that once he finishes his class 10, he would opt for this. Not only is the IB
course more expensive than a regular school, the chance that a child going for it
would ultimately pursue his graduate programmes abroad is also high. A two-year IB
course costs about Rs 4 lakh, compared to Rs 1 lakh that you would pay for a regular
CBSE or ISC school.
Manisha and Manish know that this would be an expensive proposition. They would like
to save enough to fund the full cost of his foreign degree, but are not entirely sure
they would be able to. The actual amounts they would need would depend on the
course, college and country.
When the child is between the ages of 10 and 14, regular day-to-day expenses are
also high. School fees in secondary classes are higher than those in primary, and
children also need a lot of academic and non-academic stimulation outside school.
This would mean a mixture of tuitions and lessons. Rishab takes lessons in playing the
drums, speech and drama. These add up to Rs 18,000 a year.
7 star strategies for your child's future
February 26, 2008
This is also the age of having to make large-ticket purchases. Gameboys,
Playstations, the latest skating boards and other 'toys' cost quite a packet, some
starting upwards of Rs 25,000. You can manage to spin some yarn and convince your
eight-year-old that the Barbie she has is better than the Barbie she wants, but there
is no talking reason, logic or threat to a 13-year-old.
The Nandas have made several investments in equity mutual funds. They also have
two child-specific plans -- one from LIC and the other from UTI. Ideally, the Nandas
should move their portfolio more towards debt and balanced funds. One, they would
need a large sum of money to pay the IB fees after Rishab completes his 10th
standard.
Also, since he is likely to go abroad for his undergraduate studies, their requirements
of funds would be sooner than usual. In case the stockmarket enters a lull phase after
four years, the largely equity portfolio of the couple could prove a problem.
Right now, Rishab is keen on pursuing his athletics and art. The Nandas know that
these are unconventional choices, but if Rishab does stick to either of these and
decides to pursue a career in it, they would encourage his choice.
Manisha was an advertising executive who switched careers to become a teacher.
She wants Rishab to have the guidance that enables him to discover his aptitudes so
that he doesn't waste years working in a profession he does not really want to be in.
"But," she says proudly, "at the end of the day, I think he is a survivor. Like me."
5. Terrible teens
In Delhi, Priyanka Verma is one busy 16-year-old. She is in her 12th standard and
preparing for her board exams pretty much takes up all her time now. She has opted
for the science stream and is studying physics, chemistry, mathematics and computer
science at Shriram School in Gurgaon.
Her mother, Sarika Verma, is an arts teacher and had noticed, very early, Priyanka's
creative bent of mind. "But," she says, "my husband had the foresight to advise her
that even if she wanted to subsequently pursue a career in arts, it would benefit her
to opt for the science stream at this level." Priyanka's father, Ashutosh Verma, works
in the Indian Trade Promotion Organisation.
Priyanka has now found a career that will allow an artistic expression of her science
education - she wants to be an architect. Not only that, Priyanka also decided on a
foreign language early on, and now she is learning French at an advanced level. This
means that she could opt to study architecture at a good college in France, where
the cost of education would be lower than in the US or the UK.
The Vermas are self-confessedly not very money-savvy. They decided early on that
Priyanka's education would have the first claim on their finances; everything else
would be secondary. Right now, these education expenses are high. Priyanka takes
tuitions in a couple of subjects and these cost Rs 300-400 an hour. This, added to
school fees, the bus charges of going to school and coming back home and other
expenses aggregate to a neat Rs 20,000 a month.
"There was no room to splurge or go on binges. We knew we had limited resources
and, for us, spending was not a way of living. We set our priorities and refused to
worry about anything else," Sarika says.
The Vermas have left what they managed to save in their saving bank account. They
will have to drum up the funds once Priyanka secures admission in a college of her
choice. They are looking at the option of taking an educational loan to augment their
reserves.
7 star strategies for your child's future
When the child is between 14 and 18, the first big goal draws close. The money
needed for higher education should be ready and ideally, a large chunk of it should be
moved into debt and balanced funds. A 50 per cent exposure to equity is sufficient at
this stage.
Those sending their children abroad - for undergraduate or post-graduate studies -
should be in a position to provide for at least the first couple of years. If you do not
have enough saved up, you can seek an educational loan from a bank. Usually, kids
find part-time work that helps fund a part of their education or, in the least, provides
for their living expenses once they settle down in their new country and campus.
Ideally, earmark your investments for your needs. If the monthly SIP of Rs 7,000 is
going into junior's college fund, the Rs 4,000 one could be the marriage resource. As
the event draws close, you could switch the investment from an equity to a debt
fund. This would allow it to continue earning higher returns than a bank account while
being absolutely liquid.
Sarika is certain that her daughter is a bright spark. "My only dream is that in her life
she should be able to get opportunities to use her many talents," she says.
As for her marriage, it is still far away. "Even if I am rich, I wouldn't splurge on her
wedding; I am totally against that kind of fanfare," she says.
6. Action!
It all comes to pass now, the years of swinging between anticipation and hope. Now
is when your constant refrain of "go to your room and study" goes through its test.
And the money you have put away finally finds its purpose.
Bina Sharma's older son Prabhat is doing his electronics and communications
engineering in Bangalore. As he prepares to finish this and zone in on an area of
specialisation for his post-graduate course, Bina feels a mixture of relief and anxiety.
For one, Prabhat is bright enough to have got through a better college. But, she did
not want him to stay home for a whole year and prepare for the engineering entrance
exam. So, he joined the college where he got admission. This means that if he does
not get through to an IIT for his post-graduate degree, it is best that he go abroad
for it. By the time that would be happening, the younger son would be starting his
first year of college, seeking a medical degree in all likelihood. Bina is remarkably calm
for someone who is juggling so much.
"Prabhat is in two minds and has not decided whether he wants to do a Master's in
Engineering or an MBA," she says. "My sense is that he'll stick to the technical line. If
he does, he might choose to pursue his Master's in aeronautical engineering or
continue in electronics and communications. Either way, if he does not make it to a
top rung college in India, he would go abroad."
A postgraduate degree abroad is much easier to manage compared to an
undergraduate one. All said, it would cost about Rs 40 lakh (Rs 4 million) a year to
study in the US. This means an outlay of Rs 80 lakh (Rs 8 million) for a postgraduate
course, compared to Rs 1.6 crore (Rs 16 million) for an undergraduate degree. Bina
has started planning and has put away a part of this. By the time Prabhat finishes his
degree, she should have the rest of the money on board. If her resources fall short,
the Sharmas may have to take an educational loan.
The Sharmas have been forecasting their finances towards these goals. While they
meet their monthly expenses from the money generated by the business of Bina's
husband, Vipin, her salary is saved in its entirety. They have invested in equities,
mutual funds, fixed deposits and provident funds. They also have bought some real
estate with the express purpose of liquidating it to meet the kids' college expenses.
7 star strategies for your child's future
February 26, 2008
A 25 per cent equity allocation is ideal at this stage. While the remaining money is
invested in lower-risk debt instruments, this 25 per cent would give the kicker of
higher returns.
College expenses cannot be calculated to the last rupee in advance as various factors
come into play on securing admission. Prabhat is planning to pursue a technical
degree, so the possibility of getting sponsorships and fee waivers is higher. However,
the couple needs to peg a basic minimum and work towards it.
The current expenses of the family are also high. Bina paid Rs 150,000 for the first
year of Prabhat's engineering. Over this, he incurs a monthly expense of Rs 8,000.
Bina is focused on her kids having a sound base in education. Once they graduate,
they are free to choose any career they want. She feels that Prabhat's rational
expectations would hold him in good stead through his education and career.
After the stress of steering two boys through their teens, Bina is looking forward to
the final satisfaction of seeing them settle down. "I will then put up my feet and
finally relax," she crystal gazes.
7. The last mile
Sumona Gupta did not want to make the career decisions of her daughters for them.
Snigdha, 23, works in advertising in Google for Hyderabad, and Shaila, 16, is an
aspiring fashion designer. Now that Snigdha is 'settled' professionally, Sumona is
certain that like her choice of an occupation, she would also let her daughter choose
who she wants to marry.
Sumona exudes the confidence of a successful parent -- one who has done the right
thing for her daughters and who can now take it easy and enjoy their success.
Sumona freelances in real estate, helping in renting, buying and selling of property.
Her husband, Sumit, has a shore-based job in a marine operations company in Dubai.
Together, they have set aside some money for their daughters. Most of this is in the
form of equities.
"When my daughter does get married, I would like it to be a big wedding; not overtly
so, but within our budget," Sumona says. A wedding dress for a bride would cost
between Rs 5,000 and Rs 60,000. Of course, if you have the resources you can even
spend a couple of lakh for an outfit. Food for guests sets you back by Rs 50-2,000 a
plate. Ideally, the funds for the kids should be moved out of equity at this stage.
If you have set aside enough, you could leave a small portion, about 5 per cent of the
portfolio, in equity to improve your returns. Investments in gold, ideally in bars and
coins or units of a gold exchange - traded fund, would also come into use now. There
are hardly any expenses you have to incur on behalf of the child now, they have their
own salaries to pay for most of their needs.
Sumona would rather worry about her daughters' financial stability than who they
would marry and when. "There is nothing very secure in a married life," she says. In
fact, she would like Snigdha to go for a postgraduate course, such as an MBA, than
find a man and settle down immediately.
Parenting is full of paradoxes. Even as we wait for the child to cross her next
milestone, we begin to miss the precociousness of the earlier stage. As they wean
themselves away, all we can do is gather all the special moments we have had and air
out their warmth every now and then.
When they grow into adults - people with careers, aspirations and points of view - we
can only wonder how they were ever so small that they fitted into the crook of our
arm. If we have planned ahead and made our children's journey to adulthood that
much easier, that is a job well done, a life well lived
Padmapani is a name for Lokeshvara.
Avalokiteśvara (Sanskrit, "Lord who looks down", Tibetan: སྤྱན་རས་གཟིགས་, Wylie: spyan ras gzigs, THL: Chenrézik) is a bodhisattva who embodies the compassion of all Buddhas. This bodhisattva is variably depicted and described and is portrayed in different cultures as either female or male. In Chinese Buddhism, Avalokiteśvara has become the somewhat different female figure Guanyin. In Cambodia, he appears as Lokeśvara.
Avalokiteśvara is one of the more widely revered bodhisattvas in mainstream Mahayana Buddhism as well as unofficially in Theravada Buddhism.
ETYMOLOGY
The name Avalokiteśvara combines the verbal prefix ava "down", lokita, a past participle of the verb lok "to notice, behold, observe", here used in an active sense; and finally īśvara, "lord", "ruler", "sovereign" or "master". In accordance with sandhi (Sanskrit rules of sound combination), a+iśvara becomes eśvara. Combined, the parts mean "lord who gazes down (at the world)". The word loka ("world") is absent from the name, but the phrase is implied. It does appear in the Cambodian form of the name, Lokeśvara.
The earliest translation of the name into Chinese by authors such as Xuanzang was Guānzìzài (Chinese: 觀自在), not the form used in East Asian Buddhism today, Guanyin (Chinese: 觀音). It was initially thought that this was due to a lack of fluency, as Guanzizai indicates the original Sanskrit form was actually Avalokitasvara, "who looks down upon sound" (i.e., the cries of sentient beings who need help). It is now understood that was the original form, and is also the origin of Guanyin "Perceiving sound, cries", a translation furthered by the tendency of some Chinese translators, notably Kumārajīva, to use the variant 觀世音 Guānshìyīn "who perceives the world's lamentations"—wherein lok was read as simultaneously meaning both "to look" and "world" (Sanskrit loka; Chinese: 世; pinyin: shì). The original form Avalokitasvara appears in Sanskrit fragments of the fifth century.
This earlier Sanskrit name was supplanted by the form containing the ending -īśvara "lord"; Avalokiteśvara does not occur in Sanskrit before the seventh century.
The original meaning of the name fits the Buddhist understanding of the role of a bodhisattva. The reinterpretation presenting him as an īśvara shows a strong influence of Hinduism, as the term īśvara was usually connected to the Hindu notion of Krishna (in Vaishnavism) or Śiva (in Shaivism) as the Supreme Lord, Creator and Ruler of the world. Some attributes of such a god were transmitted to the bodhisattva, but the mainstream of those who venerated Avalokiteśvara upheld the Buddhist rejection of the doctrine of any creator god.
In Sanskrit, Avalokiteśvara is also referred to as Padmapāni ("Holder of the Lotus") or Lokeśvara ("Lord of the World"). In Tibetan, Avalokiteśvara is Chenrézik, (Tibetan: སྤྱན་རས་གཟིགས་) and is said to emanate as the Dalai Lama the Karmapa and other high lamas. An etymology of the Tibetan name Chenrézik is spyan "eye", ras "continuity" and gzig "to look". This gives the meaning of one who always looks upon all beings (with the eye of compassion).
ORIGIN
MAHAYANA ACCOUNT
According to Mahāyāna doctrine, Avalokiteśvara is the bodhisattva who has made a great vow to assist sentient beings in times of difficulty and to postpone his own buddhahood until he has assisted every sentient being in achieving nirvana. Mahayana sutras associated with Avalokiteśvara include the following:
Lotus Sutra
Kāraṇḍavyūhasūtra
Heart Sutra (Heart Sūtra)
Nīlakaṇṭha Dhāraṇī Sutra
Eleven-Faced Avalokitesvara Heart Dharani Sutra
Cundī Dhāraṇī Sūtra
The Lotus Sutra is generally accepted to be the earliest literature teaching about the doctrines of Avalokiteśvara. These are found in the Lotus Sutra chapter 25 (Chinese: 觀世音菩薩普門品). This chapter is devoted to Avalokiteśvara, describing him as a compassionate bodhisattva who hears the cries of sentient beings, and who works tirelessly to help those who call upon his name. A total of 33 different manifestations of Avalokiteśvara are described, including female manifestations, all to suit the minds of various beings. The chapter consists of both a prose and a verse section. This earliest source often circulates separately as its own sutra, called the Avalokiteśvara Sūtra (Chinese: 觀世音經; pinyin: Guānshìyīn jīng), and is commonly recited or chanted at Buddhist temples in East Asia.
When the Chinese monk Faxian traveled to Mathura in India around 400 CE, he wrote about monks presenting offerings to Avalokiteśvara. When Xuanzang traveled to India in the 7th century, he provided eyewitness accounts of Avalokiteśvara statues being venerated by devotees of all walks of life, from kings, to monks, to laypeople. Avalokiteśvara remained popular in India until the 12th century when Muslim invaders conquered the land and destroyed Buddhist monasteries.
In Chinese Buddhism and East Asia, Tangmi practices for the 18-armed form of Avalokiteśvara called Cundī are very popular. These practices have their basis in early Indian Vajrayana: her origins lie with a yakshini cult in Bengal and Orissa and her name in Sanskrit "connotes a prostitute or other woman of low caste but specifically denotes a prominent local ogress ... whose divinised form becomes the subject of an important Buddhist cult starting in the eighth century". The popularity of Cundī is attested by the three extant translations of the Cundī Dhāraṇī Sūtra from Sanskrit to Chinese, made from the end of the seventh century to the beginning of the eighth century. In late imperial China, these early esoteric traditions still thrived in Buddhist communities. Robert Gimello has also observed that in these communities, the esoteric practices of Cundī were extremely popular among both the populace and the elite.
In the Tiantai school, six forms of Avalokiteśvara are defined. Each of the bodhisattva's six qualities are said to break the hindrances respectively of the six realms of existence: hell-beings, pretas, animals, humans, asuras, and devas.
THERAVADA ACCOUNT
Veneration of Avalokiteśvara Bodhisattva has continued to the present day in Sri Lanka, where he is called Nātha. In more recent times, some western-educated Theravādins have attempted to identify Nātha with Maitreya Bodhisattva. However, traditions and basic iconography, including an image of Amitābha Buddha on the front of the crown, identify Nātha as Avalokiteśvara. Andrew Skilton writes:
... It is clear from sculptural evidence alone that the Mahāyāna was fairly widespread throughout [Sri Lanka], although the modern account of the history of Buddhism on the island presents an unbroken and pure lineage of Theravāda. (One can only assume that similar trends were transmitted to other parts of Southeast Asia with Sri Lankan ordination lineages.) Relics of an extensive cult of Avalokiteśvara can be seen in the present-day figure of Nātha.
Avalokiteśvara is popularly worshiped in Myanmar, where he is called Lokanat, and Thailand, where he is called Lokesvara.
MODERN SCHOLARSHIP
Western scholars have not reached a consensus on the origin of the reverence for Avalokiteśvara.
Some have suggested that Avalokiteśvara, along with many other supernatural beings in Buddhism, was a borrowing or absorption by Mahayana Buddhism of one or more deities from Hinduism, in particular Shiva or Vishnu, although the reason for this suggestion is because of the current name of the bodhisattva: Avalokiteśvara.
The Japanese scholar Shu Hikosaka on the basis of his study of Buddhist scriptures, ancient Tamil literary sources, as well as field survey, proposes the hypothesis that, the ancient mount Potalaka, the residence of Avalokiteśvara described in the Gaṇḍavyūha Sūtra and Xuanzang’s Great Tang Records on the Western Regions, is the real mountain Pothigai in Ambasamudram, Tirunelveli, Tamil Nadu. Shu also says that mount Potalaka has been a sacred place for the people of South India from time immemorial. With the spread of Buddhism in the region beginning at the time of the great king Aśoka in the third century BCE, it became a holy place also for Buddhists who gradually became dominant as a number of their hermits settled there. The local people, though, mainly remained followers of the Hindu religion. The mixed Hindu-Buddhist cult culminated in the formation of the figure of Avalokiteśvara.
The name Lokeśvara should not be confused with that of Lokeśvararāja, the Buddha under whom Dharmakara became a monk and made forty-eight vows before becoming Amitābha.
MANTRAS AND DHARANIS
Mahāyāna Buddhism relates Avalokiteśvara to the six-syllable mantra oṃ maṇi padme hūṃ. In Tibetan Buddhism, due to his association with this mantra, one form of Avalokiteśvara is called Ṣaḍākṣarī "Lord of the Six Syllables" in Sanskrit. Recitation of this mantra along with prayer beads is the most popular religious practice in Tibetan Buddhism. The connection between this famous mantra and Avalokiteśvara occurs for the first time in the Kāraṇḍavyūhasūtra. This text is first dated to around the late 4th century CE to the early 5th century CE. In this sūtra, a bodhisattva is told by the Buddha that recitation of this mantra while focusing on the sound can lead to the attainment of eight hundred samādhis. The Kāraṇḍavyūha Sūtra also features the first appearance of the dhāraṇī of Cundī, which occurs at the end of the sūtra text. After the bodhisattva finally attains samādhi with the mantra "oṃ maṇipadme hūṃ", he is then able to observe 77 koṭīs of fully enlightened buddhas replying to him in one voice with the Cundī Dhāraṇī: namaḥ saptānāṃ samyaksaṃbuddha koṭīnāṃ tadyathā, oṃ cale cule cunde svāhā.
In Shingon Buddhism, the mantra for Avalokiteśvara is On aruri kya sowa ka (Japanese: おん あるりきゃ そわか?)
The Nīlakaṇṭha Dhāraṇī is an 82-syllable dhāraṇī for Avalokiteśvara.
THOUSAND-ARMED AVALOKITESVARA
One prominent Buddhist story tells of Avalokiteśvara vowing never to rest until he had freed all sentient beings from saṃsāra. Despite strenuous effort, he realizes that still many unhappy beings were yet to be saved. After struggling to comprehend the needs of so many, his head splits into eleven pieces. Amitābha, seeing his plight, gives him eleven heads with which to hear the cries of the suffering. Upon hearing these cries and comprehending them, Avalokiteśvara attempts to reach out to all those who needed aid, but found that his two arms shattered into pieces. Once more, Amitābha comes to his aid and invests him with a thousand arms with which to aid the suffering multitudes.
The Bao'en Temple located in northwestern Sichuan has an outstanding wooden image of the Thousand-Armed Avalokiteśvara, an example of Ming dynasty decorative sculpture.
TIBETAN BUDDHIST BELIEFS CONCERNING CHENREZIG
Avalokiteśvara is an important deity in Tibetan Buddhism, and is regarded in the Vajrayana teachings as a Buddha.
In Tibetan Buddhism, Tara came into existence from a single tear shed by Avalokiteśvara. When the tear fell to the ground it created a lake, and a lotus opening in the lake revealed Tara. In another version of this story, Tara emerges from the heart of Avalokiteśvara. In either version, it is Avalokiteśvara's outpouring of compassion which manifests Tara as a being.
MANIFESTATIONS
Avalokiteśvara has an extraordinarily large number of manifestations in different forms (including wisdom goddesses (vidyaas) directly associated with him in images and texts).
______________________________________________
A mural is any piece of artwork painted or applied directly on a wall, ceiling or other large permanent surface. A distinguishing characteristic of mural painting is that the architectural elements of the given space are harmoniously incorporated into the picture.
Some wall paintings are painted on large canvases, which are then attached to the wall (e.g., with marouflage). Whether these works can be accurately called "murals" is a subject of some controversy in the art world, but the technique has been in common use since the late 19th century.
HISTORY
Murals of sorts date to Upper Paleolithic times such as the paintings in the Chauvet Cave in Ardèche department of southern France (around 30,000 BC). Many ancient murals have survived in Egyptian tombs (around 3150 BC), the Minoan palaces (Middle period III of the Neopalatial period, 1700-1600 BC) and in Pompeii (around 100 BC - AD 79).
During the Middle Ages murals were usually executed on dry plaster (secco). In Italy, circa 1300, the technique of painting of frescos on wet plaster was reintroduced and led to a significant increase in the quality of mural painting.
In modern times, the term became more well-known with the Mexican "muralista" art movement (Diego Rivera, David Siqueiros, or José Orozco). There are many different styles and techniques. The best-known is probably fresco, which uses water-soluble paints with a damp lime wash, a rapid use of the resulting mixture over a large surface, and often in parts (but with a sense of the whole). The colors lighten as they dry. The marouflage method has also been used for millennia.
Murals today are painted in a variety of ways, using oil or water-based media. The styles can vary from abstract to trompe-l'œil (a French term for "fool" or "trick the eye"). Initiated by the works of mural artists like Graham Rust or Rainer Maria Latzke in the 1980s, trompe-l'oeil painting has experienced a renaissance in private and public buildings in Europe. Today, the beauty of a wall mural has become much more widely available with a technique whereby a painting or photographic image is transferred to poster paper or canvas which is then pasted to a wall surface (see wallpaper, Frescography) to give the effect of either a hand-painted mural or realistic scene.
TECHNIQUE
In the history of mural several methods have been used:
A fresco painting, from the Italian word affresco which derives from the adjective fresco ("fresh"), describes a method in which the paint is applied on plaster on walls or ceilings. The buon fresco technique consists of painting in pigment mixed with water on a thin layer of wet, fresh, lime mortar or plaster. The pigment is then absorbed by the wet plaster; after a number of hours, the plaster dries and reacts with the air: it is this chemical reaction which fixes the pigment particles in the plaster. After this the painting stays for a long time up to centuries in fresh and brilliant colors.
Fresco-secco painting is done on dry plaster (secco is "dry" in Italian). The pigments thus require a binding medium, such as egg (tempera), glue or oil to attach the pigment to the wall.
Mezzo-fresco is painted on nearly-dry plaster, and was defined by the sixteenth-century author Ignazio Pozzo as "firm enough not to take a thumb-print" so that the pigment only penetrates slightly into the plaster. By the end of the sixteenth century this had largely displaced the buon fresco method, and was used by painters such as Gianbattista Tiepolo or Michelangelo. This technique had, in reduced form, the advantages of a secco work.
MATERIAL
In Greco-Roman times, mostly encaustic colors applied in a cold state were used.
Tempera painting is one of the oldest known methods in mural painting. In tempera, the pigments are bound in an albuminous medium such as egg yolk or egg white diluted in water.
In 16th-century Europe, oil painting on canvas arose as an easier method for mural painting. The advantage was that the artwork could be completed in the artist’s studio and later transported to its destination and there attached to the wall or ceiling. Oil paint can be said to be the least satisfactory medium for murals because of its lack of brilliance in colour. Also the pigments are yellowed by the binder or are more easily affected by atmospheric conditions. The canvas itself is more subject to rapid deterioration than a plaster ground. Different muralists tend to become experts in their preferred medium and application, whether that be oil paints, emulsion or acrylic paints applied by brush, roller or airbrush/aerosols. Clients will often ask for a particular style and the artist may adjust to the appropriate technique.
A consultation usually leads to a detailed design and layout of the proposed mural with a price quote that the client approves before the muralist starts on the work. The area to be painted can be gridded to match the design allowing the image to be scaled accurately step by step. In some cases the design is projected straight onto the wall and traced with pencil before painting begins. Some muralists will paint directly without any prior sketching, preferring the spontaneous technique.
Once completed the mural can be given coats of varnish or protective acrylic glaze to protect the work from UV rays and surface damage.
As an alternative to a hand-painted or airbrushed mural, digitally printed murals can also be applied to surfaces. Already existing murals can be photographed and then be reproduced in near-to-original quality.
The disadvantages of pre-fabricated murals and decals are that they are often mass-produced and lack the allure and exclusivity of an original artwork. They are often not fitted to the individual wall sizes of the client and their personal ideas or wishes can not be added to the mural as it progresses. The Frescography technique, a digital manufacturing method (CAM) invented by Rainer Maria Latzke addresses some of the personalisation and size restrictions.
Digital techniques are commonly used in advertisements. A "wallscape" is a large advertisement on or attached to the outside wall of a building. Wallscapes can be painted directly on the wall as a mural, or printed on vinyl and securely attached to the wall in the manner of a billboard. Although not strictly classed as murals, large scale printed media are often referred to as such. Advertising murals were traditionally painted onto buildings and shops by sign-writers, later as large scale poster billboards.
SIGNIFICANCE OF MURALS
Murals are important in that they bring art into the public sphere. Due to the size, cost, and work involved in creating a mural, muralists must often be commissioned by a sponsor. Often it is the local government or a business, but many murals have been paid for with grants of patronage. For artists, their work gets a wide audience who otherwise might not set foot in an art gallery. A city benefits by the beauty of a work of art.
Murals can be a relatively effective tool of social emancipation or achieving a political goal. Murals have sometimes been created against the law, or have been commissioned by local bars and coffeeshops. Often, the visual effects are an enticement to attract public attention to social issues. State-sponsored public art expressions, particularly murals, are often used by totalitarian regimes as a tool of mass-control and propaganda. However, despite the propagandist character of that works, some of them still have an artistic value.
Murals can have a dramatic impact whether consciously or subconsciously on the attitudes of passers by, when they are added to areas where people live and work. It can also be argued that the presence of large, public murals can add aesthetic improvement to the daily lives of residents or that of employees at a corporate venue.
Other world-famous murals can be found in Mexico, New York, Philadelphia, Belfast, Derry, Los Angeles, Nicaragua, Cuba and in India. They have functioned as an important means of communication for members of socially, ethnically and racially divided communities in times of conflict. They also proved to be an effective tool in establishing a dialogue and hence solving the cleavage in the long run. The Indian state Kerala has exclusive murals. These Kerala mural painting are on walls of Hindu temples. They can be dated from 9th century AD.
The San Bartolo murals of the Maya civilization in Guatemala, are the oldest example of this art in Mesoamerica and are dated at 300 BC.
Many rural towns have begun using murals to create tourist attractions in order to boost economic income. Colquitt, Georgia is one such town. Colquitt was chosen to host the 2010 Global Mural Conference. The town has more than twelve murals completed, and will host the Conference along with Dothan, Alabama, and Blakely, Georgia. In the summer of 2010, Colquitt will begin work on their Icon Mural.
WIKIPEDIA
A little edgy...some moody lighting...implied nude...sexy model with an awesome figure... what do you think?
The word ‘Jyotish’ has derived from ‘jyot + isha’. ‘Jyot’ implies to “light” and ‘isha’ to ‘lord’. It is also known as Vedic Astrology, an extant form of ancient astrology still practiced in India as a name of Indian Astrology. Jyotish is the instructional constituent of the Rig Veda, and as such is a Vedanga, or “body part” of the Vedas. Jyotish is called the Eye of the Veda, for its ability to see into the future. Jyotish has historically been part of a continuous “holistic” approach to living and to spiritual practice within the life of Hindus predominant in India. The birth chart cast on the Indian System is truly unique since the Indian system makes corrections for the fact that our Zodiac / Universe is moving and not fixed ( by the Big Bang theory of creation of).
The eastern gray squirrel (Sciurus carolinensis), also known, particularly outside of North America, as simply the grey squirrel, is a tree squirrel in the genus Sciurus. It is native to eastern North America, where it is the most prodigious and ecologically essential natural forest regenerator. Widely introduced to certain places around the world, the eastern gray squirrel in Europe, in particular, is regarded as an invasive species.
In Europe, Sciurus carolinensis is included since 2016 in the list of Invasive Alien Species of Union concern (the Union list). This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.
Distribution
Sciurus carolinensis is native to the eastern and midwestern United States, and to the southerly portions of the central provinces of Canada. In the mid-1800s the population in the midwestern United States was described as being "truly astonishing", but human predation and habitat destruction through deforestation resulted in drastic population reductions, to the point that the animal was almost absent from Illinois by 1900.
The native range of the eastern gray squirrel overlaps with that of the fox squirrel (Sciurus niger), with which it is sometimes confused, although the core of the fox squirrel's range is slightly more to the west. The eastern gray squirrel is found from New Brunswick, through southwestern Quebec and throughout southern Ontario plus in southern Manitoba, south to East Texas and Florida. Breeding eastern gray squirrels are found in Nova Scotia, but whether this population was introduced or came from natural range expansion is not known.
A prolific and adaptable species, the eastern gray squirrel has also been introduced to, and thrives in, several regions of the western United States and in 1966, this squirrel was introduced onto Vancouver Island in Western Canada in the area of Metchosin, and has spread widely from there. They are considered highly invasive and a threat to both the local ecosystem and the native squirrel, the American red squirrel.
Overseas, eastern gray squirrels in Europe are a concern because they have displaced some of the native squirrels there. They have been introduced into Ireland, Britain, Italy, South Africa, and Australia (where it was extirpated by 1973).
In Ireland, the native squirrel – also colored red – the Eurasian red squirrel S. vulgaris – has been displaced in several eastern counties, though it still remains common in the south and west of the country. The gray squirrel is also an invasive species in Britain; it has spread across the country and has largely displaced the red squirrel. That such a displacement might happen in Italy is of concern, as gray squirrels might spread to other parts of mainland Europe.
The generic name, Sciurus, is derived from two Greek words, skia 'shadow' and oura 'tail'. This name alludes to the squirrel sitting in the shadow of its tail. The specific epithet, carolinensis, refers to the Carolinas, where the species was first recorded and where the animal is still extremely common. In the United Kingdom and Canada, it is simply referred to as the "grey squirrel". In the US, "eastern" is used to differentiate the species from the western gray squirrel (Sciurus griseus).
Characteristics
The eastern gray squirrel has predominantly gray fur, but it can have a brownish color. It has a usual white underside as compared to the typical brownish-orange underside of the fox squirrel. It has a large bushy tail. Particularly in urban situations where the risk of predation is reduced, both white – and black-colored individuals are quite often found. The melanistic form, which is almost entirely black, is predominant in certain populations and in certain geographic areas, such as in large parts of southeastern Canada. Melanistic squirrels appear to exhibit a higher cold tolerance than the common gray morph; when exposed to −10 °C, black squirrels showed an 18% reduction in heat loss, a 20% reduction in basal metabolic rate, and an 11% increase to non-shivering thermogenesis capacity when compared to the common gray morph. The black coloration is caused by an incomplete dominant mutation of MC1R, where E+/E+ is a wild type squirrel, E+/EB is brown-black, and EB/EB is black.
The head and body length is from 23 to 30 cm (9.1 to 11.8 in), the tail from 19 to 25 cm (7.5 to 9.8 in), and the adult weight varies between 400 and 600 g (14 and 21 oz). They do not display sexual dimorphism, meaning there is no gender difference in size or coloration.
The tracks of an eastern gray squirrel are difficult to distinguish from the related fox squirrel and Abert's squirrel, though the latter's range is almost entirely different from the gray's. Like all squirrels, the eastern gray shows four toes on the front feet and five on the hind feet. The hind foot-pad is often not visible in the track. When bounding or moving at speed, the front foot tracks will be behind the hind foot tracks. The bounding stride can be two to three feet long.
The dental formula of the eastern gray squirrel is 1023/1013 (upper teeth/lower teeth).
1.0.2.3
1.0.1.3
× 2 = 22 total teeth.
Incisors exhibit indeterminate growth, meaning they grow consistently throughout life, and their cheek teeth exhibit brachydont (low-crowned teeth) and bunodont (having tubercles on crowns) structures.
Growth and ontogeny
Newborn gray squirrels weigh 13–18 grams and are entirely hairless and pink, although vibrissae are present at birth. 7–10 days postpartum, the skin begins to darken, just before the juvenile pelage grows in. Lower incisors erupt 19–21 days postpartum, while upper incisors erupt after 4 weeks. Cheek teeth erupt during week 6. Eyes open after 21–42 days, and ears open 3–4 weeks postpartum. Weaning is initiated around 7 weeks postpartum, and is usually finished by week 10, followed by the loss of the juvenile pelage. Full adult body mass is achieved by 8–9 months after birth.
Diseases
Diseases such as typhus, plague, and tularemia are spread by eastern gray squirrels. If not properly treated, these diseases have the potential to kill squirrels. When bitten or exposed to bodily fluids, humans can contract these diseases. Also carried by eastern gray squirrels are parasites such as ringworm, fleas, lice, mites, and ticks which can kill their squirrel host. Their skin may become rough, blotchy, and prone to hair loss due to the mite parasite during the chilly winter months. The parasites are not transferred to people when these squirrels reside in attics or homes. A frequent illness spread by ticks is Lyme disease. Ticks can also spread Rocky Mountain spotted fever. It can result in damage to internal organs including the heart and kidney if not properly treated. An eastern gray squirrel is susceptible to illness. They are susceptible to diseases including fibromatosis and squirrelpox. A squirrel with fibromatosis, a virus-induced illness, may grow massive skin tumors all over the body. Blindness could result from a tumor that is located close to a squirrel's eye.
Behavior and ecology
Like many members of the family Sciuridae, the eastern gray squirrel is a scatter-hoarder; it hoards food in numerous small caches for later recovery. Some caches are quite temporary, especially those made near the site of a sudden abundance of food which can be retrieved within hours or days for reburial in a more secure site. Others are more permanent and are not retrieved until months later. Each squirrel is estimated to make several thousand caches each season. The squirrels have very accurate spatial memory for the locations of these caches, using distant and nearby landmarks to retrieve them. Smell is used partly to uncover food caches, and also to find food in other squirrels' caches. Scent can be unreliable when the ground is too dry or covered in snow.
Squirrels sometimes use deceptive behavior to prevent other animals from retrieving cached food. For example, they will pretend to bury the object if they feel that they are being watched. They do this by preparing the spot as usual, for instance, digging a hole or widening a crack, miming the placement of the food, while actually concealing it in their mouths, and then covering up the "cache" as if they had deposited the object. They also hide behind vegetation while burying food or hide it high up in trees (if their rival is not arboreal). Such a complex repertoire suggests that the behaviours are not innate, and imply theory of mind thinking.
The eastern gray squirrel is one of very few mammalian species that can descend a tree head-first. It does this by turning its feet so the claws of its hind paws are backward-pointing and can grip the tree bark.
Eastern gray squirrels build a type of nest, known as a drey, in the forks of trees, consisting mainly of dry leaves and twigs. The dreys are roughly spherical, about 30 to 60 cm in diameter and are usually insulated with moss, thistledown, dried grass, and feathers to reduce heat loss. Males and females may share the same nest for short times during the breeding season, and during cold winter spells. Squirrels may share a drey to stay warm. They may also nest in the attic or exterior walls of a house, where they may be regarded as pests, as well as fire hazards due to their habit of gnawing on electrical cables. In addition, squirrels may inhabit a permanent tree den hollowed out in the trunk or a large branch of a tree.
Eastern gray squirrels are crepuscular, or more active during the early and late hours of the day, and tend to avoid the heat in the middle of a summer day. They do not hibernate.
Eastern gray squirrels can breed twice a year, but younger and less experienced mothers normally have a single litter per year in the spring. Depending on forage availability, older and more experienced females may breed again in summer. In a year of abundant food, 36% of females bear two litters, but none will do so in a year of poor food. Their breeding seasons are December to February and May to June, though this is slightly delayed in more northern latitudes. The first litter is born in February or March, the second in June or July, though, again, bearing may be advanced or delayed by a few weeks depending on climate, temperature, and forage availability. In any given breeding season, an average of 61 – 66% of females bear young. If a female fails to conceive or loses her young to unusually cold weather or predation, she re-enters estrus and has a later litter. Five days before a female enters estrus, she may attract up to 34 males from up to 500 meters away. Eastern gray squirrels exhibit a form of polyandry, in which the competing males will form a hierarchy of dominance, and the female will mate with multiple males depending on the hierarchy established.
Normally, one to four young are born in each litter, but the largest possible litter size is eight. The gestation period is about 44 days. The young are weaned around 10 weeks, though some may wean up to six weeks later in the wild. They begin to leave the nest after 12 weeks, with autumn born young often wintering with their mother. Only one in four squirrel kits survives to one year of age, with mortality around 55% for the following year. Mortality rates then decrease to around 30% for following years until they increase sharply at eight years of age.
Rarely, eastern gray females can enter estrus as early as five and a half months old, but females are not normally fertile until at least one year of age. Their mean age of first estrus is 1.25 years. The presence of a fertile male will induce ovulation in a female going through estrus. Male eastern grays are sexually mature between one and two years of age. Reproductive longevity for females appears to be over 8 years, with 12.5 years documented in North Carolina. These squirrels can live to be 20 years old in captivity, but in the wild live much shorter lives due to predation and the challenges of their habitat. At birth, their life expectancy is 1–2 years, an adult typically can live to be six, with exceptional individuals making it to 12 years.
Communication
As in most other mammals, communication among eastern gray squirrel individuals involves both vocalizations and posturing. The species has a quite varied repertoire of vocalizations, including a squeak similar to that of a mouse, a low-pitched noise, a chatter, and a raspy "mehr mehr mehr". Other methods of communication include tail-flicking and other gestures, including facial expressions. Tail flicking and the "kuk" or "quaa" call are used to ward off and warn other squirrels about predators, as well as to announce when a predator is leaving the area. Squirrels also make an affectionate coo-purring sound that biologists call the "muk-muk" sound. This is used as a contact sound between a mother and her kits and in adulthood, by the male when he courts the female during mating season. The use of vocal and visual communication has been shown to vary by location, based on elements such as noise pollution and the amount of open space. For instance, populations living in large cities generally rely more on the visual signals, due to the generally louder environment with more areas without much visual restriction. However, in heavily wooded areas, vocal signals are used more often due to the relatively lower noise levels and a dense canopy restricting visual range.
Habitat
In the wild, eastern gray squirrels can be found inhabiting large areas of mature, dense woodland ecosystems, generally covering 100 acres (40 hectares) of land. These forests usually contain large mast-producing trees such as oaks and hickories, providing ample food sources. Oak-hickory hardwood forests are generally preferred over coniferous forests due to the greater abundance of mast forage. This is why they are found only in parts of eastern Canada which do not contain boreal forest (i.e. they are found in some parts of New Brunswick, in southwestern Quebec, throughout southern Ontario and in southern Manitoba).
Eastern gray squirrels generally prefer constructing their dens upon large tree branches and within the hollow trunks of trees. They also have been known to take shelter within abandoned bird nests. The dens are usually lined with moss plants, thistledown, dried grass, and feathers. These perhaps provide and assist in the insulation of the den, used to reduce heat loss. A cover to the den is usually built afterwards. Eastern grays squirrels also use dens for protection from prey and helps them look after their young. Young survive 40 percent less if they lived in a leaf nest compared to a den. Squirrels tend to claim 2-3 dens at the same time. Canopy and midstory Trees are used by squirrels to hide from predators such as hawks and owls. The typical squirrel ranges over 1.5 to 8 acres (0.61 to 3.24 ha) and tend to be smaller where more of them are found.
Close to human settlements, eastern gray squirrels are found in parks and back yards of houses within urban environments and in the farmlands of rural environments.
Ecosystem
Eastern Grey Squirrels are important to the ecosystem by eating a lot of seeds. By caching seeds, they help in the spread of tree seeds. Also, by eating truffles, they contribute to the spread of fungal spores. In addition, they are essential to the environment because they transport parasites. The ecology is influenced by the contribution of squirrels to nature. They often collect seeds and bury them for later consumption, but they often forget where have left them, and they have effectively planted those seeds. These seeds increase the diversity of trees by bringing additional trees into the environment. They are an important key to the forest ecosystem that they belong to.
Predation
Eastern gray squirrels predators include hawks, weasels, raccoons, bobcats, foxes, domestic and feral cats, snakes, owls, and dogs. Their primary predators are hawks, owls, and snakes. Raccoons and weasels may consume a squirrel depending on where it lives in the United States. Rattlesnakes eat squirrels in California as they are searching for food in a heavy forest. The squirrel is susceptible to be eaten by a fox in the eastern region of the United States.
In its introduced range in South Africa, it has been preyed on by African harrier-hawks. When a predator is approaching the eastern gray squirrel, other squirrels will inform the squirrel of the predator by sending an acoustic signal to let the squirrel know. The speed of a squirrel makes it hard for it to be captured by the predators.
Fossil record of the eastern gray squirrel
Twenty different Pleistocene fauna specimens contain S. carolinensis, found in Florida and dated to be as early as the late Irvingtonian period. Body size seems to have increased during the early to middle Holocene and then decreased to the present size seen today.
Diet
Eastern gray squirrels eat a range of foods, such as tree bark, tree buds, flowers, berries, many types of seeds and acorns, walnuts, and other nuts, like hazelnuts (see picture) and some types of fungi found in the forests, including fly agaric mushrooms and truffles. They can cause damage to trees by tearing the bark and eating the soft cambial tissue underneath. In Europe, sycamore and beech suffer the greatest damage. Mast-bearing gymnosperms such as cedar, hemlock, pine, and spruce are another food source, as well as angiosperms such as hickory, oak, and walnut. These trees produce important foods for them during the spring and fall months. The squirrels will vary the species they forage from depending on the season. The squirrels also raid gardens for wheat, tomatoes, corn, strawberries, and other garden crops. Sometimes they eat the tomato seeds and discard the rest. On occasion, eastern gray squirrels also prey upon insects, frogs, small rodents including other squirrels, and small birds, their eggs, and young. They also gnaw on bones, antlers, and turtle shells – likely as a source of minerals scarce in their normal diet. In urban and suburban areas, these squirrels scavenge for food in trash bins. However, these foods are not safe for them to digest because they include sugar, fat, as well as additives that can make them sick. Eastern gray squirrels are sometimes mistakenly thought to be herbivores, but they are omnivores.
Eastern gray squirrels have a high enough tolerance for humans to inhabit residential neighborhoods and raid bird feeders for millet, corn, and sunflower seeds. Some people who feed and watch birds for entertainment also intentionally feed seeds and nuts to the squirrels for the same reason. However, in the UK eastern gray squirrels can take a significant proportion of supplementary food from feeders, preventing access and reducing use by wild birds. Attraction to supplementary feeders can increase local bird nest predation, as eastern gray squirrels are more likely to forage near feeders, resulting in increased likelihood of finding nests, eggs and nestlings of small passerines.
Introductions and impact
The eastern gray squirrel is an introduced species in a variety of locations in western North America: in western Canada, to the southwest corner of British Columbia and to the city of Calgary, Alberta; in the United States, to the states of Washington and Oregon and, in California, to the city of San Francisco and the San Francisco Peninsula area in San Mateo and Santa Clara Counties, south of the city. It has become the most common squirrel in many urban and suburban habitats in western North America, from north of central California to southwest British Columbia.
By the turn of the 20th century, breeding populations of the eastern gray squirrel had been introduced into South Africa, Ireland, Italy, Australia (extirpated by 1973), and the United Kingdom.
In South Africa, though exotic, it is not usually considered an invasive species owing to its small range (only found in the extreme southwestern part of the Western Cape, going north as far as the small farming town of Franschhoek), as well because it inhabits urban areas and places greatly affected by humans, such as agricultural areas and exotic pine plantations. Here, it mostly eats acorns and pine seeds, although it will take indigenous and commercial fruit, as well. Even so, it is unable to use the natural vegetation (fynbos) found in the area, a factor which has helped to limit its spread. It does not come into contact with native squirrels due to geographic isolation (a native tree squirrel, Paraxerus cepapi, is found only in the savanna regions in the northeast of the country) and different habitats.
Gray squirrels were first introduced to Britain in the 1870s, as fashionable additions to estates. In 1921 it was reported in The Times that the Zoological Society of London had released eastern greys to breed at liberty in Regents Park:
A dozen years ago the Zoological Society of London obtained a number from a private collection in Bedfordshire for the purpose of inducing them to breed at liberty in the Gardens in Regent's Park. They were first kept in a large enclosure from which, when they had become used to visitors, they were allowed to pass in and out by a rope bridge to a tree. It was hoped that they would spread from the Gardens to the Park. After two or three years in which they seemed to be disappearing, they suddenly became ubiquitous...The grey squirrels are plainly happy and plainly give happiness to Londoners...On the other hand, grey squirrels, whether by taking advantage of tubes and buses, or by deliberate human connivance, have spread from London and are invading the country over very wide areas. They are said to drive out the red squirrel, to raid gardens, and to add to the anxieties of the pheasant breeder. We hope that fuller inquiry will not sustain these charges.
They spread rapidly across England, and then became established in both Wales and parts of southern Scotland. On mainland Britain, they have almost entirely displaced native red squirrels. Larger than red squirrels and capable of storing up to four times more fat, gray squirrels are better able to survive winter conditions. They produce more young and can live at higher densities. Gray squirrels also carry the squirrelpox virus, to which red squirrels have no immunity. When an infected gray squirrel introduces squirrelpox to a red squirrel population, its decline is 17–25 times greater than through competition alone.
In Ireland, the displacement of red squirrels has not been as rapid because only a single introduction occurred, in County Longford. Schemes have been introduced to control the population of gray squirrels in Ireland to encourage the native red squirrels. Eastern gray squirrels have also been introduced to Italy, and the European Union has expressed concern that they will similarly displace the red squirrel from parts of the European continent.
Main article: Tree squirrel § As food
Gray squirrels were eaten in earlier times by Native Americans and their meat is still popular with hunters across most of their range in North America. Today, it is still available for human consumption and is occasionally sold in the United Kingdom. However, physicians in the United States have warned that squirrel brains should not be eaten, because of the risk that they may carry Creutzfeldt–Jakob disease.
Displacement of red squirrels
Further information: Eastern gray squirrels in Europe
In Britain and Ireland, the eastern gray squirrel is not regulated by natural predators, other than the European pine marten, which is generally absent from England and Wales. This has aided its rapid population growth and has led to the species being classed as a pest. Measures are being devised to reduce its numbers, including a campaign starting in 2006 named "Save Our Squirrels" using the slogan "Save a red, eat a grey!" which attempted to re-introduce squirrel meat in to the local market, with celebrity chefs promoting the idea, cookbooks introducing recipes containing squirrel and the Forestry Commission providing a regular supply of squirrel meat to British restaurants, factories and butchers. In areas where relict populations of red squirrels survive, such as the islands of Anglesey, Brownsea and the Isle of Wight, programs exist to eradicate gray squirrels and prevent them from reaching these areas in order to allow red squirrel populations to recover and grow.
Although complex and controversial, the main factor in the eastern gray squirrel's displacement of the red squirrel is thought to be its greater fitness, hence a competitive advantage over the red squirrel on all measures. Within 15 years of the grey squirrel's introduction to a red squirrel habitat, red squirrel populations are extinct. The eastern gray squirrel tends to be larger and stronger than the red squirrel and has been shown to have a greater ability to store fat for winter. Due to the lack of trees in their native Ireland for them to reside in, red squirrels are the only species being harmed by the invasion of grey squirrels. The squirrel can, therefore, compete more effectively for a larger share of the available food, resulting in relatively lower survival and breeding rates among the red squirrel. Parapoxvirus may also be a strongly contributing factor; red squirrels have long been fatally affected by the disease, while the eastern gray squirrels are unaffected, but thought to be carriers – although how the virus is transmitted has yet to be determined. Red squirrel extinction rates can be 20–25 times greater in areas with confirmed cases of squirrel pox than they are in areas without the disease. This competitive action done between these two squirrels is reasoned to qualify the eastern gray squirrel as a keystone species because since the eastern gray squirrel is coming and wiping out the red squirrels, there would be a reduced chance of competition hence more eastern gray squirrels will come in to Ireland. However, several cases of red squirrels surviving have been reported, as they have developed an immunity – although their population is still being massively affected. The red squirrel is also less tolerant of habitat destruction and fragmentation, which has led to its population decline, while the more adaptable eastern gray squirrel has taken advantage and expanded. Methods done to control this competition between these squirrels are that red squirrels should remain in their original habitats, such as Ireland, while the grey squirrels should be kept out of these places entirely as a means of controlling this squirrel competition.
Similar factors appear to have been at play in the Pacific region of North America, where the native American red squirrel has been largely displaced by the eastern gray squirrel in parks and forests throughout much of the region.
Ironically, "fears" for the future of the eastern gray squirrel arose in 2008, as the melanistic form (black) began to spread through the southern British population. In the UK, if a "grey squirrel" (eastern gray squirrel) is trapped, under the Wildlife and Countryside Act 1981, it is illegal to release it or to allow it to escape into the wild; instead, it is legally required be "humanely dispatched".
In the late 1990s, Italy's National Wildlife Institute and University of Turin launched an eradication attempt to halt the spread of gray squirrels in northwest Italy, but court action by animal rights groups blocked this. Hence gray squirrels are expected to cross the Alps into France and Switzerland in the next few decades