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Wow, what an Epic Joshua Tree National Park, California tour. Guided by the Evolutionary Futures Lab team
The latest on Instagram:
The program was part of the Nordic-Baltic Impact Week SOCAP program.
A business bridge for Sweden, the Nordic Baltics, and Silicon Valley.
Evolutionary Futures Lab:
The NBIW - SOCAP program is organized by CleanTech Region Impact Group. Accelerating Nordic-Baltic CleanTech solutions
Photo and video credit: Lars Ling
All rights reserved (c) copyright.
Life's a Great Big Fun House when you're trapped inside with two cats and you discover that all you wanted to get done you got done, mostly, and so it comes to this:
Serious ontological studies. Science and whatnot rendered incomprehensible through a visual medium.
Curiouser and curiouser...
Atheist myths debunked - Abiogenesis - the spontaneous generation of life from sterile matter.
Abiogenesis - the atheist and evolutionist belief - that life can spontaneously generate itself from sterile matter, whenever environmental conditions are conducive .... And the belief that this actually happened in the early Earth.
Is it possible?
IMPOSSIBLE ACCORDING TO INFORMATION THEORY.
Three fundamentals are essential for the material universe to exist: matter - energy - information.
Obviously, all theories about how the universe operates, and its origins, must take account of all three. However, every evolutionary, origin of life hypothesis yet devised (primordial soup, hydrothermal vent, etc. etc.) concentrates on the chemistry/physics of life, i.e. the interaction of matter and energy.
Atheists and evolutionists have virtually ignored the essential role and origin of information. We should demand to know why? Especially as we are told (through the popular media and education system) that an evolutionary, origin of life scenario, should be regarded as irrefutable, scientific fact.
Atheists and evolutionists are well aware that the information required for life cannot just arise of its own accord in a primordial soup. So why do they usually omit this crucial fact from their origin of life story?
In order to store information, a storage code is required. Just as the alphabet and language is the code used to store information in the written word, life requires both the information itself, which controls the construction and operation of all living things, and the means of storing that information. DNA is the storage code for living things.
No evolutionary, origin of life hypothesis has ever explained either how the DNA storage system was formed, or how the information encoded within that DNA storage system originated. In fact, even to attempt to look for the origin of information in physical matter is to ignore the natural laws about information.
Information theory completely rules out the spontaneous generation of life from non-life.
Information theory tells us: ANY MODEL FOR THE ORIGIN OF LIFE BASED SOLELY ON PHYSICAL AND/OR CHEMICAL PROCESSES, IS INHERENTLY FALSE. And: THERE IS NO KNOWN LAW OF NATURE, NO KNOWN PROCESS AND NO KNOWN SEQUENCE OF EVENTS, WHICH CAN CAUSE INFORMATION TO ORIGINATE BY ITSELF IN MATTER… So information theory not only rules out all evolutionary hypotheses which cannot explain the origin of information in original life, it also rules out all evolutionary hypotheses which cannot explain the origin of the completely new, increasingly complex information which would be required to be added to a gene pool for progressive evolution to take place in existing life.
Because of their zealous and unshakable faith in Darwinian evolution, most evolutionists choose to ignore this. They simply refuse to face this most important question of all, where does the complex information essential for all life come from? The reason seems obvious, it is because there are only two answers which could be compatible with the evolution fable, both are unscientific nonsense which violate information theory. They are: 1. That information can just arise magically out of nowhere. OR 2. That the material universe is an intelligent entity, which can actually create information.
(See more on genetic information and the DNA code later on)
Verdict of science - abiogenesis is not possible.
IMPOSSIBLE ACCORDING TO THE LAW OF BIOGENESIS.
The Law of Biogenesis rules out the spontaneous generation of life from non-living matter under all known circumstances. All modern scientists now accept this well tested law as valid. In fact, the whole concept of medical sterilisation, hygiene & food preservation is totally dependent on this law.
No sensible scientist would dare to claim that spontaneous generation of life ever happens in the world today, and there is no reason whatsoever to believe that this Law (like every natural law) is not always valid, in all places and at all times, within the material universe.
Yet, amazingly, in order to support biological evolution, evolutionists are quite prepared to flout this well, established Law and to resurrect the ancient belief in abiogenesis (life arising from non-life). Like latter-day advocates of the ancient Greek belief (that the goddess Gea could make life arise spontaneously from stones), evolutionists and atheists routinely present to the public, the preposterous notion that, original life on earth (and even elsewhere in the universe) just spontaneously generated itself from inert matter. Apparently, all that was required to bypass this well established Law was a chance accumulation of chemicals in some alchemist’s type brew of ‘primordial soup’ combined with raw energy from the sun, lightning or geothermal forces. (Such is their faith in the creative powers of matter). They call this science? Incredible!
Verdict of science - abiogenesis is not possible.
IMPOSSIBLE ACCORDING TO THE SECOND LAW OF THERMODYNAMICS.
The second Law of Thermodynamics rules out the spontaneous generation of life from non-life as a chance event. Even if we ignore the above reasons why spontaneous generation of life is impossible, the formation and arrangement by chance of all the components required for living cells is also impossible. The arrangement of all the components within the simplest of living cells is extremelprecise; these components cannot just arrange themselves by chance.
According to the Second Law of Thermodynamics, when left to themselves, things naturally become more disordered, rather than more ordered. Or in other words, things will naturally go to more probable arrangements and disorder is overwhelmingly more probable than order. Disorder actually increases with the passage of time and also with the application of raw (undirected) energy (for example, heat).
Yet we are repeatedly told the evolution fable, that the numerous components required to form a first, self-replicating, living cell just assembled themselves in precise order, by pure chance, over a vast period of time, aided by the random application of raw, undirected energy.
Verdict of science - abiogenesis is not possible.
IMPOSSIBLE ACCORDING TO THE LAW OF CAUSE AND EFFECT.
A fundamental principle of science is the law of cause and effect. It is a primary law of science, and the very basis of the scientific method.
The law of cause and effect tells us that an effect cannot be greater than its cause/s.
Life is not an intrinsic property of matter/energy - so it is beyond the capabilities of matter/energy to produce a property (life) it doesn't possess.
The interaction of matter and energy cannot produce an effect with properties extra and superior to its own properties, that would violate the law of cause and effect.
Can chemistry create biology - which has entirely different properties to its own?
Of course it can't.
Biology includes such properties as genetic information, the DNA code, consciousness and intelligence. To believe that chemistry can create biology - means believing that something inanimate can create additional, new properties that it doesn't possess. To exceed the limitations of its own properties would violate the law of cause and effect.
For matter/energy to be able to produce life whenever environmental conditions permit, it would have to be inherently predisposed to produce life.
It would have to embody an inherent plan/blueprint/instructions for life, as one of its properties. The inevitable question then has to be - where does an inherent predisposition for life come from? It can only signify the existence of purpose in the universe and that is something atheists could never accept.
A purpose, order or plan can only come from a planner or intelligent entity. So it is a catch 22 situation for atheists ... the atheist/ evolutionist belief in abiogenesis either violates the law of cause and effect, OR is an admission of purpose in the universe. It can only be one or the other. Atheists cannot possibly accept the existence of purpose in the universe, because that would be the end of atheism. So the atheist belief in abiogenesis violates the law of cause and effect.
Verdict of science - abiogenesis is not possible.
IMPOSSIBLE ACCORDING TO MATHEMATICS.
Even if we ignore the Law of Biogenesis, Information Theory and the Second Law of Thermodynamics (which all completely rule out the spontaneous generation of a living cell from non-living matter). Mathematical probability also rules out the spontaneous generation of life from non-living matter.
The laws of probability are summed up in the Law of Chance. According to this Law, when odds against a chance event are 10 to the power of 15, the chance of that event happening are negligible on a terrestrial scale. At odds of 10 to the power of 50, there is virtually no chance, even on a cosmic scale. The most generous and favourable, mathematical odds against a single living cell appearing in this way by chance are a staggering 10 to the power of 40,000. A more likely calculation would put the odds at an even more awesome 10 to the power of 119,850. Remember odds of 10 to the power of 50 is sufficient to make an event virtually impossible (except, perhaps, by magic!!).
Verdict of science - abiogenesis is not possible
Fred Hoyle, The Big Bang in Astronomy, New Scientist 19 Nov 1981. p.526. On the origin of life in primeval soup.
“I don’t know how long it is going to be before astronomers generally recognise that the combinatorial arrangement of not even one among the many thousands of biopolymers on which life depends could have been arrived at by natural processes here on the Earth. Astronomers will have a little difficulty at understanding this because they will be assured by biologists that it is not so. The biologists having been assured in their turn by others that it is not so. The “others” are a group of persons who believe, quite openly, in mathematical miracles. They advocate the belief that tucked away in nature, outside of normal physics, there is a law which performs miracles.”
“Since science does not have the faintest idea how life on earth originated, it would only be honest to confess this to other scientists, to grantors, and to the public at large. Prominent scientists speaking ex cathedra, should refrain from polarising the minds of students and young productive scientists with statements that are based solely on beliefs.” Bio-informaticist, Hubert P. Yockey. Journal of Theoretical Biology [Vol 91, 1981, p 13].
Conclusion: Abiogenesis is impossible - it is just another atheist myth debunked by science.
Evolutionists and atheists are quite entitled to abandon the scientific method and all common sense by choosing to believe that all the necessary information for life can just appear in matter, as if by magic. They can also choose to believe that: the Laws of; Biogenesis, Mathematical Probability, Cause and Effect and Second Law of Thermodynamics, were all somehow magically suspended to enable their purported evolution of life from sterile matter to take place. They can believe whatever they like. But they have no right to present such unscientific, flights of fancy through the media and our education system, as though they are supported by science.
More about DNA and the origin of life.
The discovery of DNA should have been the death knell for evolution. It is only because atheists and evolutionists tend to manipulate and interpret evidence to suit their own preconceptions that makes them believe DNA is evidence FOR evolution.
It is clear that there is no natural mechanism which can produce constructional, biological information, such as that encoded in DNA.
Information Theory (and common sense) tells us that the unguided interaction of matter and energy cannot produce constructive information.
Do atheists/evolutionists even know where the very first, genetic information in the alleged Primordial Soup came from?
Of course they don't, but with the usual bravado, they bluff it out, and regardless, they rashly present the spontaneous generation of life as a scientific fact.
However, a fact, it certainly isn't .... and good science it certainly isn't.
Even though atheists/evolutionists have no idea whatsoever about how the first, genetic information originated, they still claim that the spontaneous generation of life (abiogenesis) is an established scientific fact, but this is completely disingenuous. Apart from the fact that abiogenesis violates the Law of Biogenesis, the Law of Cause and Effect and the Second Law of Thermodynamics, it also violates Information Theory.
Evolutionists/atheists have an enormous problem with explaining how the DNA code itself originated. However that is not even the major problem. The impression is given to the public by evolutionists that they only have to find an explanation for the origin of DNA by natural processes - and the problem of the origin of genetic information will have been solved.
That is a confusion in the minds of many people that evolutionists/atheists cynically exploit,
Explaining how DNA was formed by chemical processes, explains only how the information storage medium was formed, it tells us nothing about the origin of the information it carries.
To clarify this it helps to compare DNA to other information, storage mediums.
For example, if we compare DNA to the written word, we understand that the alphabet is a tangible medium for storing, recording and expressing information, it is not information in itself. The information is recorded in the sequence of letters, forming meaningful words.
You could say that the alphabet is the 'hardware' created from paper and ink, and the sequential arrangement of the letters is the software. The software is a mental construct, not a physical one.
The same applies to DNA. DNA is not information of itself, just like the alphabet it is the medium for storing and expressing information. It is an amazingly efficient storage medium. However, it is the sequence or arrangement of the amino acids which is the actual information, not the DNA code.
So, if evolutionists are ever able to explain how DNA was formed by chemical processes, it would explain only how the information storage medium was formed. It will tell us nothing about the origin of the information it carries.
Thus, when atheists and evolutionists tell us it is only a matter of time before 'science' will be able to fill the 'gaps' in our knowledge and explain the origin of genetic information, they are not being honest. Explaining the origin of the 'hardware' by natural processes is an entirely different matter to explaining the origin of the software.
Next time you hear evolutionists/atheists skating over the problem of the origin of genetic information with their usual bluff and bluster, and parroting their usual nonsense about science being able to fill such gaps in knowledge in the future, don't be fooled. They cannot explain the origin of genetic information, and never will be able to. The software cannot be created by chemical processes or the interaction of energy and matter, it is not possible. If you don't believe that. then by all means put it to the test, by challenging any evolutionist to explain how genetic information (not DNA) can originate by natural means? I can guarantee they won't be able to do so.
Atheists often argue that the energy from the Sun can overcome the problem of entropy enabling an increase in comlexity that the origin of life requires - because the Earth is an open system, but that is clearly erroneous.
We can see entropy happening here and now, it happens everyday on Earth.
We are living in the OPEN system of the Earth, and yet we are well aware of entropy.
We see that the Sun does not halt or reverse entropy, in fact we see the opposite.
The raw energy and heat from the Sun, unless harnessed, does damage, things all around us obey the law - they deteriorate, rot, erode and decay, they do not naturally improve.
If you paint your house, the Sun, and the weather effects caused by the Sun, will eventually damage the paintwork, it will crack and peel after a few years. The hotter the Sun (the greater the energy input) the quicker it will happen.
Secondly, even if it were true that in an open system things can defy the law of entropy, natural laws are laws for the whole universe, and the universe, as a whole, is a closed system.
So what can we deduce from this?
Can the effects of entropy ever be reversed of halted? Obviously when you paint your house, you are reversing the bad effects of entropy for a short period, but you have to keep doing it, it is not permanent. Moreover, the energy you are using to repair and temporarily reverse the effects of entropy, is directed and guided by your skill and intelligence.
The atheist argument about the Earth being an open system is clearly not a valid one.
There are only 2 ways the effects of entropy can be temporarily decreased, halted or reversed by an input of energy. That is:
1. A directive means guiding the energy input.
OR,
2. A directive or conversion mechanism possessed by the recipient of the energy to utilise it in a constructive way.
For their argument to be valid atheists would have to
explain what it is that guides or directs the energy from the Sun to enable it to perform the task of creating order from disorder in the so-called primordial soup? And they are unable to do so.
Evolutionism: The Religion That Offers Nothing.
www.youtube.com/watch?v=znXF0S6D_Ts&list=TLqiH-mJoVPB...
FOUNDATIONS OF SCIENCE
The Law of Cause and Effect. Dominant Principle of Classical Physics. David L. Bergman and Glen C. Collins
www.thewarfareismental.net/b/wp-content/uploads/2011/02/b...
"The Big Bang's Failed Predictions and Failures to Predict: (Updated Aug 3, 2017.) As documented below, trust in the big bang's predictive ability has been misplaced when compared to the actual astronomical observations that were made, in large part, in hopes of affirming the theory."
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.
Greetings mate! As many of you know, I love marrying art, science, and math in my fine art portrait and landscape photography!
The 45surf and gold 45 revolver swimsuits, shirts, logos, designs, and lingerie are designed in accordance with the golden ratio! More about the design and my philosophy of "no retouching" on the beautiful goddesses in my new book:
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"Photographing Women Models: Portrait, Swimsuit, Lingerie, Boudoir, Fine Art, & Fashion Photography Exalting the Venus Goddess Archetype"
If you would like a free review copy, message me!
And here's more on the golden ratio which appears in many of my landscape and portrait photographs (while shaping the proportions of the golden gun)!
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The dx4/dt=ic above the gun on the lingerie derives from my new physics books devoted to Light, Time, Dimension Theory!
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Beautiful swimsuit bikini model goddess!
Golden Ratio Lingerie Model Goddess LTD Theory Lingerie dx4/dt=ic! The Birth of Venus, Athena, and Artemis! Girls and Guns!
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I am working on several books on "epic photography," and I recently finished a related one titled: The Golden Number Ratio Principle: Why the Fibonacci Numbers Exalt Beauty and How to Create PHI Compositions in Art, Design, & Photography: An Artistic and Scientific Introduction to the Golden Mean . Message me on facebook for a free review copy!
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The Golden Ratio informs a lot of my art and photographic composition. The Golden Ratio also informs the design of the golden revolver on all the swimsuits and lingerie, as well as the 45surf logo! Not so long ago, I came up with the Golden Ratio Principle which describes why The Golden Ratio is so beautiful.
The Golden Number Ratio Principle: Dr. E’s Golden Ratio Principle: The golden ratio exalts beauty because the number is a characteristic of the mathematically and physically most efficient manners of growth and distribution, on both evolutionary and purely physical levels. The golden ratio ensures that the proportions and structure of that which came before provide the proportions and structure of that which comes after. Robust, ordered growth is naturally associated with health and beauty, and thus we evolved to perceive the golden ratio harmonies as inherently beautiful, as we saw and felt their presence in all vital growth and life—in the salient features and proportions of humans and nature alike, from the distribution of our facial features and bones to the arrangements of petals, leaves, and sunflowers seeds. As ratios between Fibonacci Numbers offer the closest whole-number approximations to the golden ratio, and as seeds, cells, leaves, bones, and other physical entities appear in whole numbers, the Fibonacci Numbers oft appear in nature’s elements as “growth’s numbers.” From the dawn of time, humanity sought to salute their gods in art and temples exalting the same proportion by which all their vital sustenance and they themselves had been created—the golden ratio.
The Birth of Venus! Beautiful Golden Ratio Swimsuit Bikini Model Goddess! Helen of Troy! She was tall, thin, fit, and quite pretty!
Read all about how classical art such as The Birth of Venus inspires all my photography!
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"Photographing Women Models: Portrait, Swimsuit, Lingerie, Boudoir, Fine Art, & Fashion Photography Exalting the Venus Goddess Archetype"
The Manchester Museum, Oxford Road, Manchester, Greater Manchester.
The museum's first collections were assembled by the Manchester Society of Natural History formed in 1821 with the purchase of the collection of John Leigh Philips. In 1850 the collections of the Manchester Geological Society were added. By the 1860s both societies encountered financial difficulties and, on the advice of the evolutionary biologist Thomas Huxley, Owens College (now the University of Manchester) accepted responsibility for the collections in 1867. The museum in Peter Street was sold in 1875 after Owens College moved to new buildings in Oxford Street.
The college commissioned Alfred Waterhouse, architect of London's Natural History Museum, to design a museum to house the collections for the benefit of students and the public on a site in Oxford Road (then Oxford Street). The Manchester Museum was opened to the public in 1888. At the time, the scientific departments of the college were immediately adjacent, and students entered the galleries from their teaching rooms in the Beyer Building.
Two subsequent extensions mirror the development of its collections. The 1912 pavilion was largely funded by Jesse Haworth, a textile merchant, to house the archaeological and Egyptological collections acquired through excavations he had supported. The 1927 extension was built to house the ethnographic collections. The Gothic Revival street frontage which continues to the Whitworth Hall has been ingeniously integrated by three generations of the Waterhouse family. When the adjacent University Dental Hospital of Manchester moved to a new site, its old building was used for teaching and subsequently occupied by the museum.
The museum is one of the University of Manchester's 'cultural assets', along with the Whitworth Art Gallery, John Rylands Library, Jodrell Bank visitor centre and others.
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Nothing you see here is real, even though the conversion or the presented background story might be based historical facts. BEWARE!
Some background:
The Su-18 was the final evolutionary step in the long journey of the Su-7 fighter bomber. Seeking to improve low-speed and take-off/landing performance of the Su-7B fighter-bomber, in 1963 the Sukhoi OKB with input from TsAGI created a variable-sweep wing technology demonstrator. The Su-7IG (internal designation S-22I, NATO designation "Fitter-B"), converted from a production Su-7BM, had fixed inner portions of the wing with movable outer segments which could be swept to 28°, 45°, or 62°.
A fixed inner wing simplified construction, allowing the manufacturer to retain the Su-7 landing gear and avoiding the need for complex pivoting underwing hardpoints, and it minimized the shift in the center of pressure relative to the center of mass with change in wing sweep. The new wing also had extensive leading-edge slats and trailing-edge flaps. Su-7IG first flew on 2 August 1966 with V. S. Ilyushin at the controls, becoming the first Soviet variable geometry aircraft. Testing revealed that take-off and landing speeds had decreased by 50–60 km/h (31–37 mph) compared to the conventional Su-7.
The production aircraft was named Su-17 (NATO designation "Fitter-C", factory designation S-32) and was unofficially dubbed Strizh (Стриж, martlet) in service. Aside from the new wing, it differed from its predecessor Su-7 in having a new canopy and a dorsal fuselage spine for additional fuel and avionics. The Su-17 first flew on 1 July 1969.
The Su-17 saw several development steps, ending with the capable Su-17/22M3 and Su-17/22M4; the latter made its maiden flight in 1980 and the last variants were produced until 1990.
The Su-22M4 was also operated by the Soviet Naval Aviation (Авиация военно-морского флота in Russian, or Aviatsiya Voenno-Morskogo Flota, literally "aviation of the military maritime fleet") in the attack role, and from the beginning it was clear that the type had no sufficient capability for tactical strikes, esp. against sea targets. The Su-24 tactical bomber was an option, but it was complex and expensive, so that an upgrade of the Su-17 was considered. Primary requirement was a more capable radar/attack suite, tailored to a naval environment, and a better/more modern engine, esp. with a better fuel efficiency.
OKB Sukhoi started to take on the task in 1982. Effectively the design team tried to create a "Su-24 light" on the basis of as many proven Su-17/22 elements as possible. The project received the internal designation S-54D. Mission avionics were to comprise the ‘котёнок‘ (= ‘Kitten’) suite, a slimmed-down 'Puma' nav/attack system optimized for naval environment. This system complex consisted of two Orion-A superimposed radar scanners for nav/attack, a dedicated Relyef terrain clearance radar to provide automatic control of flights at low and extremely low altitudes, and an Orbita-10-58 onboard computer.
It soon became clear that the original Su-17/22 airframe with nose air intake and its central shock cone did not offer sufficient space for the radar scanners, so OKB Sukhoi had to modify the complete nose section in order to fit a large radome. This radically modified aircraft was designated T-54DM and presented as a mock-up in 1984.
To create sufficient room, the box-shaped air intakes were moved to the flanks and into the wing roots, what meant that the original NR-30 cannons were omitted. As a positive side effect, top speed at height and supersonic performance were reinstated since the Su-17M4's fixed nose cone was replaced by effective, adjustable splitter plates (not unlike the design on the Su-15 interceptor) in the new air intakes - getting the new aircraft's top speed back to more than 2.000 km/h at height. On the other side, the space for the original air duct around the cockpit could be used for avionics and other mission equipment, including a pair of more modern GSh-30-1 30 mm cannons in the lower front fuselage with a 150-round magazine each, which were more effective against ground and air targets alike.
Concerning the engine, the Su-17's Lyulka AL-21F-3 afterburning turbojet was to be replaced by the new and promising Soyuz R-79F-100 turbofan that yielded about 15% more thrust than the original AL-21F, even though fuel consumption was not much better and reliability remained a serious problem throughout the Su-18's career, how the type was officially called in service when it was delivered in early 1987 to the Baltic and Black Sea fleet.
When the aircraft was discovered on NATO’s satellite pictures, it was erroneously interpreted as a Su-22 export version for China (since the new nose arrangement reminded a lot of the Q-5 modification of the MiG-19 fighter), and some ‘experts’ even considered the Su-18 to be an interceptor version of the swing-wing fighter bomber. Anyway, since the Su-18 was still seen as part of the huge Su-7 family it kept its ‘Fitter’ ASCC code, with the ‘N’ suffix.
The Su-18’s service was short and ambivalent, though. The type was only introduced to the Soviet Naval Aviation, since its котёнок avionics suite was rather limited in scope and could not match up with the Su-24’s ‘Puma’ system. Additionally, the Su-27 multi-role fighter had become a more versatile option for the Soviet Air Force, which had begun to face a severe re-structuring program.
Positive asset was the fact that the Su-18 did not require much flight training – no trainer version was ever built and training was done on Su-17M3 two-seaters. On the other side the single crew layout coupled with the complex weapon system made flying and weapon operations at the same time rather demanding, so that the Su-18 could hardly play out its full potential.
Only about 120 Su-18s were produced until 1990, and in a move to eliminate single engine strike aircraft from its inventory the Russian Air Force already retired its last Su-17M4 along with its fleet of MiG-23/27s in 1998, while the Su-18 in Naval Aviation service soldiered on until 2000. Some countries like Peru and Indonesia showed interest in these aircraft, but all were destroyed in the course of the bilateral START (Strategic Arms Reduction Treaty) treaty.
General characteristics:
Crew: 1
Length: 19.02 m (62 ft 5 in)
Wingspan:
Spread: 13.68 m (44 ft 11 in)
Swept: 10.02 m (32 ft 10 in)
Height: 5.12 m (16 ft 10 in)
Wing area: 38.5 m² (415 ft²) spread, 34.5 m² (370 ft²) swept
Empty weight: 12,160 kg(12.2t) (26,810 lb)
Loaded weight: 16,400 kg(16.5t) (36,155 lb)
Fuel capacity: 3,770 kg (8,310 lb)
Powerplant:
1× Soyuz R-79F-100 turbofan, rated at 99 kN (22.275 lbf) dry thrust and 130 kN (29.250 lbf) with afterburner
Performance:
Maximum speed:
1.400 km/h (755 knots, 870 mph) at sea level, 1,860 km/h (1,005 knots, 1,156 mph, Mach 1.7) at altitude
Range:
1,150 km (620 nmi, 715 mi) combat range in hi-lo-hi attack with 2.000 kg (4.409 lb) warload; ferry range: 2.300 km (1.240 nmi, 1.430 mi)
Service ceiling: 14,200 m (46,590 ft)
Rate of climb: 230 m/s (45,275 ft/min)
Wing loading: 443 kg/m² (90.77 lb/ft²
Thrust/weight: 0.68
G-force limit: 7
Airframe lifespan: 2,000 flying hours, 20 years
Armament:
2 × 30 mm GSh-30-1 cannons, 150 RPG in the lower forward fuselage
Up to 4000 kg (8,820 lb) on ten hardpoints (three under the fixed portion of each wing, four on the fuselage sides), including Kh-23 (AS-7 'Kerry'), Kh-25 (AS-10 'Karen'), Kh-29 (AS-14 'Kedge'), Kh-31A & P (AS-17 ‘Krypton) anti-shipping/anti-radiation missiles and Kh-58 (AS-11 'Kilter') guided missiles, as well as electro-optical and laser-guided bombs, free-fall bombs, rocket pods, cluster bombs, SPPU-22-01 cannon pods with traversable barrels, ECM pods, napalm tanks, and nuclear weapons.
The kit and its assembly:
This whif creation was triggered by a discussion at whatifmodelers.com, circling around an updated/improved Su-17/22. I remembered a photoshop creation of a Su-17 with side air intakes (from an A-4) and a nose radome (probably from an F-14) in USAF-markings – a potential way to go, even though the graphic design had some flaws like the subsonic air intake design or the guns’ position right in front of the intakes. Well, “Let’s tackle that, and do it better”, and the Su-18 is my interpretation of that idea.
The kit the Su-17M4 from Smer, a kit that has nice proportions and good detail, but nothing really fits together – expect lots of putty work! From that basis only few things were actually changed or added:
• Nose intake replaced by a F-15 radome
• Side air intakes with splitter plates come from a PM Model Su-15
• The following ducts are a halved part from an Art Model Bv 155 underwing radiator
• A new seat had to be used in the cockpit
• Main wheels from a Me 262 replace the OOB parts
• New twin front wheel which retracts backwards now
• For the anti-shipping role, a pair of Kh-31 missiles and the launch rails from an ICM weapon set
My biggest concern were the air intakes and the wide ducts, since these had to be blended into the round Su-17 fuselage. For the intakes, the wing roots were cut open and the Su-15 parts inserted. The Bv 155 parts were a lucky find, as they matched perfectly in size and shape – otherwise I had had to sculpt the ducts from 2c Putty. The arrangement still looks a little brutal, but the side intakes look plausible.
The nose radome posed little problems, even though I worried for a long time that the nose section could look too bulbous for the rest of the aircraft. But finally, when the stabilizers were in place, everything looked more balanced than expected.
Changing the front wheel from the original, forward-retracting single-wheel arrangement to a rearward-retracting twin wheel creation also helped selling the new proportions.
Painting and markings:
Very early I had the idea to keep the Su-18 in Soviet/Russian service, but it should feature an unusual, yet plausible paint scheme. The Soviet/Russian Navy actually used the Su-17, but only in tactical camouflage, with green and brown upper surfaces and light blue undersides. While browsing for alternatives I came across the Su-24 (also flown by the Navy regiments), and their typical light grey/white livery was what perfectly fit my story for the aircraft.
Said and done, the model was painted in Humbrol 167 (RAF Barley Grey) from above and painted with the rattle can in a vintage VW car tone called “Grauweiß”, a very dull white. Later, panels were emphasized through dry-brushing (Humbrol 127 and 130), plus a light black ink wash and more overall dry-brushing with light grey tones. Also, some panels were painted all over the fuselage, as well as an overpainted Red Star on the fin which was replaced by a Russian Flag decal – a common experimental practice in the early 90ies, but the idea did not catch on.
Speaking of decals, these mostly come from the very complete Smer decal sheet. Personal additions are only the flags on the fin and the Russian Navy emblem on the nose.
The cockpit was painted in typical psychedelic cockpit interior turquoise, while the landing gear and the wells were painted in blue-grey (Humbrol 87); the wheel discs were kept in bright green (Humbrol 2) – a nice contrast to the rest.
The drop tanks were painted in Aluminum, for some overall contrast, and the Kh-31 missiles according to real-life pics; the launch rails were painted in Russian Underside Blue, again for variety and contrast.
While the finish of the model is far from perfect, I am satisfied with the convincing result. You could certainly place this aircraft in line with other, typical Suchoj types like the Su-7, -15, -17 and -24, and it would not look out of place! A highly effective whif, IMHO. ^^
The Spotted Towhee and the very similar Eastern Towhee used to be considered the same species, the Rufous-sided Towhee. The two forms still occur together in the Great Plains, where they sometimes interbreed. This is a common evolutionary pattern in North American birds – a holdover from when the great ice sheets split the continent down the middle, isolating birds into eastern and western populations that eventually became new species.
Early in the breeding season, male Spotted Towhees spend their mornings singing their hearts out, trying to attract a mate. Male towhees have been recorded spending 70 percent to 90 percent of their mornings singing. Almost as soon as they attract a mate, their attention shifts to other things, and they spend only about 5 percent of their time singing (so like a man!).
From:
www.allaboutbirds.org/guide/Spotted_Towhee/lifehistory
To hear their song:
www.allaboutbirds.org/guide/Spotted_Towhee/sounds
Member of the Flickr Bird Brigade
Activists for birds and wildlife
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based historical facts. BEWARE!
Some background:
The Hawker Cyclone was an evolutionary successor to the successful Hawker Typhoon and Tempest fighters and fighter-bombers of the Second World War. The Cyclone's design process was initiated in September 1942 by Sydney Camm, one of Hawker's foremost aircraft designers, to meet the Royal Air Force’s requirement for a lightweight Tempest Mk.II and V replacement.
The project, tentatively designated Tempest Mk. VIII, was formalised in January 1943 when the Air Ministry issued Specification F.2/42 around the "Tempest Light Fighter".This was followed up by Specification F.2/43, issued in May 1943, which required a high rate of climb of not less than 4,500 ft/min (23 m/s) from ground level to 20,000 feet (6,096 m), good fighting manoeu rability and a maximum speed of at least 450 mph (724 km/h) at 22,000 feet (6,705 m). The armament was to be four 20mm Hispano V cannon with a total capacity of 600 rounds, plus the capability of carrying two bombs each up to 1,000 pounds (454 kg). In April 1943, Hawker had also received Specification N.7/43 from the Admiralty, who sought a navalized version of the developing aircraft, what eventually led to the Hawker Sea Fury, which was a completely new aircraft, which only shared the general outlines of the Tempest.
The Royal Air Force was looking for a quicker solution, and Camm started working on a new laminar flow wing, which would further improve the Tempest’s speed. Further refinements were done to other aerodynamic components, too, like the radiator, since the Tempest V’s liquid-cooled Napier Sabre engine was to be used. After some experiments with new arrangements, an annular radiator directly behind the propeller was chosen – certainly inspired by fast German aircraft like the Fw 190D and developed by Napier.
A total of three prototypes were ordered; the first one was powered by a Napier Sabre IIA liquid-cooled H-24 sleeve-valve engine, generating 2,180 hp (1,625 kW), but the second and any following aircraft carried the more powerful Sabre V with 2,340 hp, driving a Rotol four-blade propeller. Later aircraft were even to carry the Napier Sabre VII, which was capable of developing 3,400–4,000 hp (2,535–2,983 kW) and pushing the top speed to 485 mph (780 km/h) and more. The third airframe was just a static test structure. However, since the differences between the Tempest and the new aircraft had become almost as big as to its predecessor, the Typhoon, the new type received its own name Cyclone.
The first Cyclone Mk. I to fly, on 30 August 1944, was NV950, and it became clear soon that the modifications would improve the Cyclone’s top speed vs. the Tempest by almost 30 mph (50 km/h), but the new components would also require a longer testing period than expected. The annular radiator frequently failed and overheated, and the new, slender wings caused directional stability problems so that the complete tail section had to be re-designed. This troubling phase took more than 6 months, so that eventual service aircraft would only be ready in mid-1945 – too late for any serious impact in the conflict.
However, since the Hawker Fury, the land-based variant of the Sea Fury, which had been developed from the Tempest for the Royal Navy in parallel, had been cancelled, the Royal Air Force still ordered 150 Cyclone fighters (F Mk. I), of which one third would also carry cameras and other reconnaissance equipment (as Cyclone FR Mk.II). Due to the end of hostilities in late 1945, this order immediately lost priority. Consequently, the first production Cyclone fighters were delivered in summer 1946 – and in the meantime, jet fighters had rendered the piston-powered fighters obsolete, at least in RAF service. As a consequence, all Cyclones were handed over to friendly Commonwealth nations and their nascent air forces, e. g. India, Thailand or Burma. India received its first Cyclones in late 1947, just when the Kashmir conflict with Pakistan entered a hot phase. The machines became quickly involved in this conflict from early 1948 onwards.
Cyclones played an important role in the strikes against hostiles at Pir Badesar and the dominating Pir Kalewa. The taking of Ramgarh fort and Pt. 6944 on the west flank of Bhimbar Gali was to be a classic close support action with Indian forces carrying out a final bayonet charge against the enemy trenches whilst RIAF Cyclones and Tempests strafed and rocketed the trenches at close quarters. On a chance reconnaissance, enemy airfields were located at Gilgit and 40 NMs south, at Chilas. Cyclones flew several strikes against the landing strips in Oct and Nov 48, cratering & damaging both and destroying several hangars, barracks and radio installations. This attack destroyed Pakistani plans to build an offensive air capability in the North. Already, with Tempests and Cyclones prowling the valleys, Pakistani re-supply by Dakotas had been limited to hazardous night flying through the valleys.
After the end of hostilities in late 1948 and the ensuing independence, the Cyclone squadrons settled into their peace time stations. However, constant engine troubles (particularly the radiator) continued to claim aircraft and lives and the skill required to land the Cyclone because of its high approach speed continued to cause several write offs. The arrival of the jet-engined Vampire were the first signs of the Cyclone’s demise. As the IAF began a rapid expansion to an all jet force, several Tempest and Cyclone squadrons began converting to Vampires, 7 Squadron being the first in Dec 49. By this time it had already been decided that the piston-engine fighters would be relegated to the fighter lead-in role to train pilots for the new jet fighters. A conversion training flight was set up at Ambala in Sep 49 with Spitfire T Mk IXs, XVIIIs and Tempests to provide 16 hrs/six weeks of supervised Tempest training. This unit eventually moved to Hakimpet two years later and operated till the end of 1952. Some Cyclone FR Mk. IIs remained in front line service until 1954, though.
General characteristics:
Crew: One
Length: 35 ft 5 3/4 in (10.83 m)
Wingspan: 42 ft 5 1/2 in (12.96 m)
Height (tail down): 15 ft 6 3/4 in (4.75 m)
Wing area: 302 ft² (28 m²)
Empty weight: 9,250 lb (4,195 kg)
Loaded weight: 11,400 lb (5,176 kg)
Max. takeoff weight: 13,640 lb (6,190 kg)
Powerplant:
1× Napier Sabre V liquid-cooled H-24 sleeve-valve engine with 2,340 hp (1,683 kW)
Performance:
Maximum speed: 460 mph (740 km/h) 18,400 ft (5,608 m),
Range: 740 mi (1,190 km)
1,530 mi (2,462 km) with two 90 gal (409 l) drop tanks
Service ceiling: 36,500 ft (11,125 m)
Rate of climb: 4,700 ft/min (23.9 m/s)
Wing loading: 37.75 lb/ft² (184.86 kg/m²)
Power/mass: 0.21 hp/lb (0.31 kW/kg)
Armament:
4× 20 mm (.79 in) Mark V Hispano cannons, 200 RPG
2× underwing hardpoints for 500 lb (227 kg) or 1,000 lb (454 kg) bombs
or 2 × 45 gal (205 l) or 2 × 90 gal (409 l) drop tanks
plus 6× 3” (76.2 mm) RP-3 rockets
The kit and its assembly:
Another episode in the series “Things to make and do with Supermarine Attacker wings”. And what started as a simple switch of wings eventually turned into a major kitbashing, since the model evolved from a modded Tempest into something more complex and conclusive.
The initial spark was the idea of a Hawker alternative to Supermarine’s Spiteful and Seafang developments – especially with their slender laminar flow wings. Wouldn’t a Hawker alternative make sense?
Said and done, I dug out a NOVO Attacker kit and a Matchbox Tempest, and started measuring – and the wing transplantation appeared feasible! I made the cut on the Tempest wing just outside of the oil cooler, and the Attacker wings were then attached to these stubs – after some gaps for the landing gear wells had been cut into the massive lower wing halves. The stunt went more smoothly than expected, the only cosmetic flaw is that the guns went pretty far outboard, but that’s negligible.
But the different wings were not enough. I had recently seen in a book a picture of a Tempest (NV 768) with an experimental annular radiator for the Sabre engine (looking like a streamlined Tempest II), and wondered if this arrangement would have been the aerodynamically more efficient solution than the bulbous chin radiator of the Tempest V and VI? I decided to integrate this feature into my build, too, even though not as a copy of the real-world arrangement. The whole nose section, even though based on the OOB Mk. V nose, was scratched and re-sculpted with lots of putty. The radiator intake comes from a FROG He 219, with the front end opened and a fan from a Matchbox Fw 190 placed inside, as well as a styrene tube for the new propeller. The latter was scratched, too, from a Matchbox He 70 spinner and single blades from an Italeri F4U, plus a metal axis. The exhaust stubs were taken OOB, but their attachment slits had to be re-engraved into the new and almost massive nose section.
Once the wings and the nose became more concrete, I found that the Tempest’s original rounded tail surfaces would not match with the new, square wings. Therefore I replaced the stabilizers with donations from a Heller F-84G and modified the fin with a new, square tip (from an Intech Fw 190D) and got rid of the fin fillet – both just small modifications, but they change the Tempest’s profile thoroughly.
In order to underline the aircraft’s new, sleek lines, I left away any ordnance – but instead I added some camera fairings: one under the rear fuselage or a pair of vertical/oblique cameras, and another camera window portside for a horizontal camera. The openings were drilled, and, after painting, the kit the camera windows were created with Humbrol Clearfix.
Painting and markings:
Somehow I thought that this aircraft had to carry Indian markings – and I had a set of standard Chakra Wheels from the late Forties period in my stash. The camouflage is, typical for early IAF machines of British origin, RAF standard, with Dark Green and Ocean Grey from above and Medium Sea Grey from below. I just used the more brownish pst-war RAF Dark Green tone (Humbrol 163), coupled with the rather light Ocean Grey from Modelmaster (2057). The underside became Humbrol 165. All interior surfaces were painted with RAF Interior Green, nothing fancy. The only colorful addition is the saffron-colored spinner, in an attempt to match the fin flash’s tone.
As a standard measure, the kit received a black ink wash and some panel post-shading with lighter tones – only subtly, since the machine was not to look too weathered and beaten, just used from its Kashmir involvements.
The national markings come from a Printscale Airspeed Oxford sheet, the tactical code with alternating white and black letters, depending on the underground (the sky fuselage band comes from a Matchbox Brewster Buffalo), was puzzled together from single letters from TL Modellbau – both seen on different contemporary RIAF aircraft.
As another, small individual detail I gave the machine a tactical code letter on the fuselage, and the small tiger emblems under the cockpit were home-printed from the official IAF No. 1 Squadron badge.
Despite the massive modifications this one is a relatively subtle result, all the changes become only visible at a second glance. A sleek aircraft, and from certain angley the Cyclone looks like an A-1 Skyraider on a diet?
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.
Testosterone
The chemical structure of testosterone.
A ball-and-stick model of testosterone.
Names
IUPAC name
17β-Hydroxyandrost-4-en-3-one
Systematic IUPAC name
(8R,9S,10R,13S,14S,17S)-17-Hydroxy-10,13-dimethyl-1,2,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-3-one
Other names
Androst-4-en-17β-ol-3-one
Identifiers
CAS Number
58-22-0 ☑
3D model (JSmol)
Interactive image
ChEBI
CHEBI:17347 ☑
ChEMBL
ChEMBL386630 ☑
ChemSpider
5791 ☑
DrugBank
DB00624 ☑
ECHA InfoCard100.000.336
KEGG
D00075 ☑
PubChem CID
6013
UNII
3XMK78S47O ☑
InChI[show]
SMILES[show]
Properties
Chemical formula
C19H28O2
Molar mass288.431 g·mol−1
Melting point155 °C
Pharmacology
ATC code
G03BA03 (WHO)
License data
EU EMA: by INN
Routes of
administration
Transdermal (gel, cream, solution, patch), by mouth (as testosterone undecanoate), in the cheek, intranasal (gel), intramuscular injection (as esters), subcutaneous pellets
Pharmacokinetics:
Bioavailability
Oral: very low (due to extensive first pass metabolism)
Protein binding
97.0–99.5% (to SHBG and albumin)[1]
Metabolism
Liver (mainly reduction and conjugation)
Biological half-life
2–4 hours[citation needed]
Excretion
Urine (90%), feces (6%)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Testosterone is the primary male sex hormone and an anabolic steroid. In male humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair.[2] In addition, testosterone is involved in health and well-being,[3] and the prevention of osteoporosis.[4] Insufficient levels of testosterone in men may lead to abnormalities including frailty and bone loss.
Testosterone is a steroid from the androstane class containing a keto and hydroxyl groups at the three and seventeen positions respectively. It is biosynthesized in several steps from cholesterol and is converted in the liver to inactive metabolites.[5] It exerts its action through binding to and activation of the androgen receptor.[5] In humans and most other vertebrates, testosterone is secreted primarily by the testicles of males and, to a lesser extent, the ovaries of females. On average, in adult males, levels of testosterone are about 7 to 8 times as great as in adult females.[6] As the metabolism of testosterone in males is more pronounced, the daily production is about 20 times greater in men.[7][8] Females are also more sensitive to the hormone.[9]
In addition to its role as a natural hormone, testosterone is used as a medication, for instance in the treatment of low testosterone levels in men and breast cancer in women.[10] Since testosterone levels decrease as men age, testosterone is sometimes used in older men to counteract this deficiency. It is also used illicitly to enhance physique and performance, for instance in athletes.
Contents
1Biological effects
1.1Before birth
1.2Early infancy
1.3Before puberty
1.4Pubertal
1.5Adult
1.6Aggression and criminality
1.7Brain
2Medical use
3Biological activity
3.1Steroid hormone activity
3.2Neurosteroid activity
4Biochemistry
4.1Biosynthesis
4.2Distribution
4.3Metabolism
4.4Levels
5Measurement
6History
7Other animals
8See also
9References
10Further reading
Biological effects[edit]
In general, androgens such as testosterone promote protein synthesis and thus growth of tissues with androgen receptors.[11] Testosterone can be described as having virilising and anabolic effects (though these categorical descriptions are somewhat arbitrary, as there is a great deal of mutual overlap between them).[12]
Anabolic effects include growth of muscle mass and strength, increased bone density and strength, and stimulation of linear growth and bone maturation.
Androgenic effects include maturation of the sex organs, particularly the penis and the formation of the scrotum in the fetus, and after birth (usually at puberty) a deepening of the voice, growth of facial hair (such as the beard) and axillary (underarm) hair. Many of these fall into the category of male secondary sex characteristics.
Testosterone effects can also be classified by the age of usual occurrence. For postnatal effects in both males and females, these are mostly dependent on the levels and duration of circulating free testosterone.
Before birth[edit]
Effects before birth are divided into two categories, classified in relation to the stages of development.
The first period occurs between 4 and 6 weeks of the gestation. Examples include genital virilisation such as midline fusion, phallic urethra, scrotal thinning and rugation, and phallic enlargement; although the role of testosterone is far smaller than that of dihydrotestosterone. There is also development of the prostate gland and seminal vesicles.
During the second trimester, androgen level is associated with sex formation.[13] This period affects the femininization or masculinization of the fetus and can be a better predictor of feminine or masculine behaviours such as sex typed behaviour than an adult's own levels. A mother's testosterone level during pregnancy is correlated with her daughter's sex-typical behavior as an adult, and the correlation is even stronger than with the daughter's own adult testosterone level.[14]
Early infancy[edit]
Early infancy androgen effects are the least understood. In the first weeks of life for male infants, testosterone levels rise. The levels remain in a pubertal range for a few months, but usually reach the barely detectable levels of childhood by 4–7 months of age.[15][16] The function of this rise in humans is unknown. It has been theorized that brain masculinization is occurring since no significant changes have been identified in other parts of the body.[17] The male brain is masculinized by the aromatization of testosterone into estrogen, which crosses the blood–brain barrier and enters the male brain, whereas female fetuses have α-fetoprotein, which binds the estrogen so that female brains are not affected.[18]
Before puberty[edit]
Before puberty effects of rising androgen levels occur in both boys and girls. These include adult-type body odor, increased oiliness of skin and hair, acne, pubarche (appearance of pubic hair), axillary hair (armpit hair), growth spurt, accelerated bone maturation, and facial hair.[19]
Pubertal[edit]
Pubertal effects begin to occur when androgen has been higher than normal adult female levels for months or years. In males, these are usual late pubertal effects, and occur in women after prolonged periods of heightened levels of free testosterone in the blood. The effects include:[19][20]
Growth of spermatogenic tissue in testicles, male fertility, penis or clitoris enlargement, increased libido and frequency of erection or clitoral engorgement occurs. Growth of jaw, brow, chin, and nose and remodeling of facial bone contours, in conjunction with human growth hormone occurs.[21] Completion of bone maturation and termination of growth. This occurs indirectly via estradiol metabolites and hence more gradually in men than women. Increased muscle strength and mass, shoulders become broader and rib cage expands, deepening of voice, growth of the Adam's apple. Enlargement of sebaceous glands. This might cause acne, subcutaneous fat in face decreases. Pubic hair extends to thighs and up toward umbilicus, development of facial hair (sideburns, beard, moustache), loss of scalp hair (androgenetic alopecia), increase in chest hair, periareolar hair, perianal hair, leg hair, armpit hair.
Adult[edit]
Testosterone is necessary for normal sperm development. It activates genes in Sertoli cells, which promote differentiation of spermatogonia. It regulates acute HPA (hypothalamic–pituitary–adrenal axis) response under dominance challenge.[22] Androgen including testosterone enhances muscle growth. Testosterone also regulates the population of thromboxane A2 receptors on megakaryocytes and platelets and hence platelet aggregation in humans.[23][24]
Adult testosterone effects are more clearly demonstrable in males than in females, but are likely important to both sexes. Some of these effects may decline as testosterone levels might decrease in the later decades of adult life.[25]
Health risks[edit]
Testosterone does not appear to increase the risk of developing prostate cancer. In people who have undergone testosterone deprivation therapy, testosterone increases beyond the castrate level have been shown to increase the rate of spread of an existing prostate cancer.[26][27][28]
Conflicting results have been obtained concerning the importance of testosterone in maintaining cardiovascular health.[29][30] Nevertheless, maintaining normal testosterone levels in elderly men has been shown to improve many parameters that are thought to reduce cardiovascular disease risk, such as increased lean body mass, decreased visceral fat mass, decreased total cholesterol, and glycemic control.[31]
High androgen levels are associated with menstrual cycle irregularities in both clinical populations and healthy women.[32]
Sexual arousal[edit]
See also: Hormones and sexual arousal
When testosterone and endorphins in ejaculated semen meet the cervical wall after sexual intercourse, females receive a spike in testosterone, endorphin, and oxytocin levels, and males after orgasm during copulation experience an increase in endorphins and a marked increase in oxytocin levels. This adds to the hospitable physiological environment in the female internal reproductive tract for conceiving, and later for nurturing the conceptus in the pre-embryonic stages, and stimulates feelings of love, desire, and paternal care in the male (this is the only time male oxytocin levels rival a female's).[citation needed]
Testosterone levels follow a nyctohemeral rhythm that peaks early each day, regardless of sexual activity.[33]
There are positive correlations between positive orgasm experience in women and testosterone levels where relaxation was a key perception of the experience. There is no correlation between testosterone and men's perceptions of their orgasm experience, and also no correlation between higher testosterone levels and greater sexual assertiveness in either sex.[34]
Sexual arousal and masturbation in women produce small increases in testosterone concentrations.[35] The plasma levels of various steroids significantly increase after masturbation in men and the testosterone levels correlate to those levels.[36]
Mammalian studies[edit]
Studies conducted in rats have indicated that their degree of sexual arousal is sensitive to reductions in testosterone. When testosterone-deprived rats were given medium levels of testosterone, their sexual behaviors (copulation, partner preference, etc.) resumed, but not when given low amounts of the same hormone. Therefore, these mammals may provide a model for studying clinical populations among humans suffering from sexual arousal deficits such as hypoactive sexual desire disorder.[37]
In every mammalian species examined demonstrated a marked increase in a male's testosterone level upon encountering a novel female. The reflexive testosterone increases in male mice is related to the male's initial level of sexual arousal.[38]
In non-human primates, it may be that testosterone in puberty stimulates sexual arousal, which allows the primate to increasingly seek out sexual experiences with females and thus creates a sexual preference for females.[39] Some research has also indicated that if testosterone is eliminated in an adult male human or other adult male primate's system, its sexual motivation decreases, but there is no corresponding decrease in ability to engage in sexual activity (mounting, ejaculating, etc.).[39]
In accordance with sperm competition theory, testosterone levels are shown to increase as a response to previously neutral stimuli when conditioned to become sexual in male rats.[40] This reaction engages penile reflexes (such as erection and ejaculation) that aid in sperm competition when more than one male is present in mating encounters, allowing for more production of successful sperm and a higher chance of reproduction.
Males[edit]
In men, higher levels of testosterone are associated with periods of sexual activity.[41][42]
Men who watch a sexually explicit movie have an average increase of 35% in testosterone, peaking at 60–90 minutes after the end of the film, but no increase is seen in men who watch sexually neutral films.[43] Men who watch sexually explicit films also report increased motivation, competitiveness, and decreased exhaustion.[44] A link has also been found between relaxation following sexual arousal and testosterone levels.[45]
Men's levels of testosterone, a hormone known to affect men's mating behaviour, changes depending on whether they are exposed to an ovulating or nonovulating woman's body odour. Men who are exposed to scents of ovulating women maintained a stable testosterone level that was higher than the testosterone level of men exposed to nonovulation cues. Testosterone levels and sexual arousal in men are heavily aware of hormone cycles in females.[46] This may be linked to the ovulatory shift hypothesis,[47] where males are adapted to respond to the ovulation cycles of females by sensing when they are most fertile and whereby females look for preferred male mates when they are the most fertile; both actions may be driven by hormones.
Females[edit]
Androgens may modulate the physiology of vaginal tissue and contribute to female genital sexual arousal.[48] Women's level of testosterone is higher when measured pre-intercourse vs pre-cuddling, as well as post-intercourse vs post-cuddling.[49] There is a time lag effect when testosterone is administered, on genital arousal in women. In addition, a continuous increase in vaginal sexual arousal may result in higher genital sensations and sexual appetitive behaviors.[50]
When females have a higher baseline level of testosterone, they have higher increases in sexual arousal levels but smaller increases in testosterone, indicating a ceiling effect on testosterone levels in females. Sexual thoughts also change the level of testosterone but not level of cortisol in the female body, and hormonal contraceptives may affect the variation in testosterone response to sexual thoughts.[51]
Testosterone may prove to be an effective treatment in female sexual arousal disorders,[52] and is available as a dermal patch. There is no FDA approved androgen preparation for the treatment of androgen insufficiency; however, it has been used off-label to treat low libido and sexual dysfunction in older women. Testosterone may be a treatment for postmenopausal women as long as they are effectively estrogenized.[52]
Romantic relationships[edit]
Falling in love decreases men's testosterone levels while increasing women's testosterone levels. There has been speculation that these changes in testosterone result in the temporary reduction of differences in behavior between the sexes.[53] However, it is suggested that after the "honeymoon phase" ends—about four years into a relationship—this change in testosterone levels is no longer apparent.[53] Men who produce less testosterone are more likely to be in a relationship[54] or married,[55] and men who produce more testosterone are more likely to divorce;[55] however, causality cannot be determined in this correlation. Marriage or commitment could cause a decrease in testosterone levels.[56] Single men who have not had relationship experience have lower testosterone levels than single men with experience. It is suggested that these single men with prior experience are in a more competitive state than their non-experienced counterparts.[57] Married men who engage in bond-maintenance activities such as spending the day with their spouse/and or child have no different testosterone levels compared to times when they do not engage in such activities. Collectively, these results suggest that the presence of competitive activities rather than bond-maintenance activities are more relevant to changes in testosterone levels.[58]
Men who produce more testosterone are more likely to engage in extramarital sex.[55] Testosterone levels do not rely on physical presence of a partner; testosterone levels of men engaging in same-city and long-distance relationships are similar.[54] Physical presence may be required for women who are in relationships for the testosterone–partner interaction, where same-city partnered women have lower testosterone levels than long-distance partnered women.[59]
Fatherhood[edit]
Fatherhood decreases testosterone levels in men, suggesting that the emotions and behavior tied to decreased testosterone promote paternal care. In humans and other species that utilize allomaternal care, paternal investment in offspring is beneficial to said offspring's survival because it allows the parental dyad to raise multiple children simultaneously. This increases the reproductive fitness of the parents, because their offspring are more likely to survive and reproduce. Paternal care increases offspring survival due to increased access to higher quality food and reduced physical and immunological threats.[60] This is particularly beneficial for humans since offspring are dependent on parents for extended periods of time and mothers have relatively short inter-birth intervals.[61] While extent of paternal care varies between cultures, higher investment in direct child care has been seen to be correlated with lower average testosterone levels as well as temporary fluctuations.[62] For instance, fluctuation in testosterone levels when a child is in distress has been found to be indicative of fathering styles. If a father's testosterone levels decrease in response to hearing their baby cry, it is an indication of empathizing with the baby. This is associated with increased nurturing behavior and better outcomes for the infant.[63]
Motivation[edit]
Testosterone levels play a major role in risk-taking during financial decisions.[64][65]
Aggression and criminality [edit]
See also: Aggression § Testosterone, and Biosocial criminology
Most studies support a link between adult criminality and testosterone, although the relationship is modest if examined separately for each sex. Nearly all studies of juvenile delinquency and testosterone are not significant. Most studies have also found testosterone to be associated with behaviors or personality traits linked with criminality such as antisocial behavior and alcoholism. Many studies have also been done on the relationship between more general aggressive behavior/feelings and testosterone. About half the studies have found a relationship and about half no relationship.[66]
Testosterone is only one of many factors that influence aggression and the effects of previous experience and environmental stimuli have been found to correlate more strongly. A few studies indicate that the testosterone derivative estradiol (one form of estrogen) might play an important role in male aggression.[66][67][68][69] Studies have also found that testosterone facilitates aggression by modulating vasopressin receptors in the hypothalamus.[70]
The sexual hormone can encourage fair behavior. For the study, subjects took part in a behavioral experiment where the distribution of a real amount of money was decided. The rules allowed both fair and unfair offers. The negotiating partner could subsequently accept or decline the offer. The fairer the offer, the less probable a refusal by the negotiating partner. If no agreement was reached, neither party earned anything. Test subjects with an artificially enhanced testosterone level generally made better, fairer offers than those who received placebos, thus reducing the risk of a rejection of their offer to a minimum. Two later studies have empirically confirmed these results.[71][72][73] However men with high testosterone were significantly 27% less generous in an ultimatum game.[74] The Annual NY Academy of Sciences has also found anabolic steroid use which increase testosterone to be higher in teenagers, and this was associated with increased violence.[75] Studies have also found administered testosterone to increase verbal aggression and anger in some participants.[76]
Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.[77] The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.[77] Thus it is the challenge of competition among males of the species that facilitates aggression and violence.[77] Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.[77] The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males.[77]
The second theory is similar and is known as "evolutionary neuroandrogenic (ENA) theory of male aggression".[78][79] Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even to the point of risking harm to the person and others. By doing so, individuals with masculinized brains as a result of pre-natal and adult life testosterone and androgens enhance their resource acquiring abilities in order to survive, attract and copulate with mates as much as possible.[78] The masculinization of the brain is not just mediated by testosterone levels at the adult stage, but also testosterone exposure in the womb as a fetus. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game.[80] Studies have also found higher pre-natal testosterone or lower digit ratio to be correlated with higher aggression in males.[81][82][83][84][85]
The rise in testosterone levels during competition predicted aggression in males but not in females.[86] Subjects who interacted with hand guns and an experimental game showed rise in testosterone and aggression.[87] Natural selection might have evolved males to be more sensitive to competitive and status challenge situations and that the interacting roles of testosterone are the essential ingredient for aggressive behaviour in these situations.[88] Testosterone produces aggression by activating subcortical areas in the brain, which may also be inhibited or suppressed by social norms or familial situations while still manifesting in diverse intensities and ways through thoughts, anger, verbal aggression, competition, dominance and physical violence.[89] Testosterone mediates attraction to cruel and violent cues in men by promoting extended viewing of violent stimuli.[90] Testosterone specific structural brain characteristic can predict aggressive behaviour in individuals.[91]
Estradiol is known to correlate with aggression in male mice.[92] Moreover, the conversion of testosterone to estradiol regulates male aggression in sparrows during breeding season.[93] Rats who were given anabolic steroids that increase testosterone were also more physically aggressive to provocation as a result of "threat sensitivity".[94]
Brain[edit]
The brain is also affected by this sexual differentiation;[13] the enzyme aromatase converts testosterone into estradiol that is responsible for masculinization of the brain in male mice. In humans, masculinization of the fetal brain appears, by observation of gender preference in patients with congenital diseases of androgen formation or androgen receptor function, to be associated with functional androgen receptors.[95]
There are some differences between a male and female brain (possibly the result of different testosterone levels), one of them being size: the male human brain is, on average, larger.[96] Men were found to have a total myelinated fiber length of 176 000 km at the age of 20, whereas in women the total length was 149 000 km (approx. 15% less).[97]
No immediate short term effects on mood or behavior were found from the administration of supraphysiologic doses of testosterone for 10 weeks on 43 healthy men.[98] A correlation between testosterone and risk tolerance in career choice exists among women.[64][99]
Attention, memory, and spatial ability are key cognitive functions affected by testosterone in humans. Preliminary evidence suggests that low testosterone levels may be a risk factor for cognitive decline and possibly for dementia of the Alzheimer's type,[100][101][102][103] a key argument in life extension medicine for the use of testosterone in anti-aging therapies. Much of the literature, however, suggests a curvilinear or even quadratic relationship between spatial performance and circulating testosterone,[104] where both hypo- and hypersecretion (deficient- and excessive-secretion) of circulating androgens have negative effects on cognition.
Medical use[edit]
Main article: Testosterone (medication)
Testosterone is used as a medication for the treatment of males with too little or no natural testosterone production, certain forms of breast cancer,[10] and gender dysphoria in transgender men. This is known as hormone replacement therapy (HRT) or testosterone replacement therapy (TRT), which maintains serum testosterone levels in the normal range. Decline of testosterone production with age has led to interest in androgen replacement therapy.[105] It is unclear if the use of testosterone for low levels due to aging is beneficial or harmful.[106]
Testosterone is included in the World Health Organization's list of essential medicines, which are the most important medications needed in a basic health system.[107] It is available as a generic medication.[10] The price depends on the form of testosterone used.[108] It can be administered as a cream or transdermal patch that is applied to the skin, by injection into a muscle, as a tablet that is placed in the cheek, or by ingestion.[10]
Common side effects from testosterone medication include acne, swelling, and breast enlargement in males.[10] Serious side effects may include liver toxicity, heart disease, and behavioral changes.[10] Women and children who are exposed may develop virilization.[10] It is recommended that individuals with prostate cancer not use the medication.[10] It can cause harm if used during pregnancy or breastfeeding.[10]
Biological activity[edit]
Steroid hormone activity[edit]
The effects of testosterone in humans and other vertebrates occur by way of multiple mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of certain estrogen receptors.[109][110] Androgens such as testosterone have also been found to bind to and activate membrane androgen receptors.[111][112][113]
Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (DHT) by the cytoplasmic enzyme 5α-reductase. DHT binds to the same androgen receptor even more strongly than testosterone, so that its androgenic potency is about 5 times that of T.[114] The T-receptor or DHT-receptor complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to specific nucleotide sequences of the chromosomal DNA. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects.
Androgen receptors occur in many different vertebrate body system tissues, and both males and females respond similarly to similar levels. Greatly differing amounts of testosterone prenatally, at puberty, and throughout life account for a share of biological differences between males and females.
The bones and the brain are two important tissues in humans where the primary effect of testosterone is by way of aromatization to estradiol. In the bones, estradiol accelerates ossification of cartilage into bone, leading to closure of the epiphyses and conclusion of growth. In the central nervous system, testosterone is aromatized to estradiol. Estradiol rather than testosterone serves as the most important feedback signal to the hypothalamus (especially affecting LH secretion).[115] In many mammals, prenatal or perinatal "masculinization" of the sexually dimorphic areas of the brain by estradiol derived from testosterone programs later male sexual behavior.[116]
Neurosteroid activity[edit]
Testosterone, via its active metabolite 3α-androstanediol, is a potent positive allosteric modulator of the GABAA receptor.[117]
Testosterone has been found to act as an antagonist of the TrkA and p75NTR, receptors for the neurotrophin nerve growth factor (NGF), with high affinity (around 5 nM).[118][119][120] In contrast to testosterone, DHEA and DHEA sulfate have been found to act as high-affinity agonists of these receptors.[118][119][120]
Testosterone is an antagonist of the sigma σ1 receptor (Ki = 1,014 or 201 nM).[121] However, the concentrations of testosterone required for binding the receptor are far above even total circulating concentrations of testosterone in adult males (which range between 10 and 35 nM).[122]
Biochemistry[edit]
Human steroidogenesis, showing testosterone near bottom.[123]
Biosynthesis[edit]
Like other steroid hormones, testosterone is derived from cholesterol (see figure).[124] The first step in the biosynthesis involves the oxidative cleavage of the side-chain of cholesterol by cholesterol side-chain cleavage enzyme (P450scc, CYP11A1), a mitochondrial cytochrome P450 oxidase with the loss of six carbon atoms to give pregnenolone. In the next step, two additional carbon atoms are removed by the CYP17A1 (17α-hydroxylase/17,20-lyase) enzyme in the endoplasmic reticulum to yield a variety of C19 steroids.[125] In addition, the 3β-hydroxyl group is oxidized by 3β-hydroxysteroid dehydrogenase to produce androstenedione. In the final and rate limiting step, the C17 keto group androstenedione is reduced by 17β-hydroxysteroid dehydrogenase to yield testosterone.
The largest amounts of testosterone (>95%) are produced by the testes in men,[2] while the adrenal glands account for most of the remainder. Testosterone is also synthesized in far smaller total quantities in women by the adrenal glands, thecal cells of the ovaries, and, during pregnancy, by the placenta.[126] In the testes, testosterone is produced by the Leydig cells.[127] The male generative glands also contain Sertoli cells, which require testosterone for spermatogenesis. Like most hormones, testosterone is supplied to target tissues in the blood where much of it is transported bound to a specific plasma protein, sex hormone-binding globulin (SHBG).
Regulation[edit]
Hypothalamic–pituitary–testicular axis
In males, testosterone is synthesized primarily in Leydig cells. The number of Leydig cells in turn is regulated by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In addition, the amount of testosterone produced by existing Leydig cells is under the control of LH, which regulates the expression of 17β-hydroxysteroid dehydrogenase.[128]
The amount of testosterone synthesized is regulated by the hypothalamic–pituitary–testicular axis (see figure to the right).[129] When testosterone levels are low, gonadotropin-releasing hormone (GnRH) is released by the hypothalamus, which in turn stimulates the pituitary gland to release FSH and LH. These latter two hormones stimulate the testis to synthesize testosterone. Finally, increasing levels of testosterone through a negative feedback loop act on the hypothalamus and pituitary to inhibit the release of GnRH and FSH/LH, respectively.
Factors affecting testosterone levels may include:
Age: Testosterone levels gradually reduce as men age.[130][131] This effect is sometimes referred to as andropause or late-onset hypogonadism.[132]
Exercise: Resistance training increases testosterone levels,[133] however, in older men, that increase can be avoided by protein ingestion.[134] Endurance training in men may lead to lower testosterone levels.[135]
Nutrients: Vitamin A deficiency may lead to sub-optimal plasma testosterone levels.[136] The secosteroid vitamin D in levels of 400–1000 IU/d (10–25 µg/d) raises testosterone levels.[137] Zinc deficiency lowers testosterone levels[138] but over-supplementation has no effect on serum testosterone.[139]
Weight loss: Reduction in weight may result in an increase in testosterone levels. Fat cells synthesize the enzyme aromatase, which converts testosterone, the male sex hormone, into estradiol, the female sex hormone.[140] However no clear association between body mass index and testosterone levels has been found.[141]
Miscellaneous: Sleep: (REM sleep) increases nocturnal testosterone levels.[142] Behavior: Dominance challenges can, in some cases, stimulate increased testosterone release in men.[143] Drugs: Natural or man-made antiandrogens including spearmint tea reduce testosterone levels.[144][145][146] Licorice can decrease the production of testosterone and this effect is greater in females.[147]
Distribution[edit]
The plasma protein binding of testosterone is 98.0 to 98.5%, with 1.5 to 2.0% free or unbound.[148] It is bound 65% to sex hormone-binding globulin (SHBG) and 33% bound weakly to albumin.[149]
Plasma protein binding of testosterone and dihydrotestosterone show
Metabolism[edit]
vte Testosterone metabolism in humans
Testosterone structures
The image above contains clickable linksTestosterone metabolism in humans. Conjugation (sulfation and glucuronidation) occurs both with testosterone and with all of the other steroids that have one or more available hydroxyl (-OH) groups in this diagram.
Both testosterone and 5α-DHT are metabolized mainly in the liver.[1][151] Approximately 50% of testosterone is metabolized via conjugation into testosterone glucuronide and to a lesser extent testosterone sulfate by glucuronosyltransferases and sulfotransferases, respectively.[1] An additional 40% of testosterone is metabolized in equal proportions into the 17-ketosteroids androsterone and etiocholanolone via the combined actions of 5α- and 5β-reductases, 3α-hydroxysteroid dehydrogenase, and 17β-HSD, in that order.[1][151][152] Androsterone and etiocholanolone are then glucuronidated and to a lesser extent sulfated similarly to testosterone.[1][151] The conjugates of testosterone and its hepatic metabolites are released from the liver into circulation and excreted in the urine and bile.[1][151][152] Only a small fraction (2%) of testosterone is excreted unchanged in the urine.[151]
In the hepatic 17-ketosteroid pathway of testosterone metabolism, testosterone is converted in the liver by 5α-reductase and 5β-reductase into 5α-DHT and the inactive 5β-DHT, respectively.[1][151] Then, 5α-DHT and 5β-DHT are converted by 3α-HSD into 3α-androstanediol and 3α-etiocholanediol, respectively.[1][151] Subsequently, 3α-androstanediol and 3α-etiocholanediol are converted by 17β-HSD into androsterone and etiocholanolone, which is followed by their conjugation and excretion.[1][151] 3β-Androstanediol and 3β-etiocholanediol can also be formed in this pathway when 5α-DHT and 5β-DHT are acted upon by 3β-HSD instead of 3α-HSD, respectively, and they can then be transformed into epiandrosterone and epietiocholanolone, respectively.[153][154] A small portion of approximately 3% of testosterone is reversibly converted in the liver into androstenedione by 17β-HSD.[152]
In addition to conjugation and the 17-ketosteroid pathway, testosterone can also be hydroxylated and oxidized in the liver by cytochrome P450 enzymes, including CYP3A4, CYP3A5, CYP2C9, CYP2C19, and CYP2D6.[155] 6β-Hydroxylation and to a lesser extent 16β-hydroxylation are the major transformations.[155] The 6β-hydroxylation of testosterone is catalyzed mainly by CYP3A4 and to a lesser extent CYP3A5 and is responsible for 75 to 80% of cytochrome P450-mediated testosterone metabolism.[155] In addition to 6β- and 16β-hydroxytestosterone, 1β-, 2α/β-, 11β-, and 15β-hydroxytestosterone are also formed as minor metabolites.[155][156] Certain cytochrome P450 enzymes such as CYP2C9 and CYP2C19 can also oxidize testosterone at the C17 position to form androstenedione.[155]
Two of the immediate metabolites of testosterone, 5α-DHT and estradiol, are biologically important and can be formed both in the liver and in extrahepatic tissues.[151] Approximately 5 to 7% of testosterone is converted by 5α-reductase into 5α-DHT, with circulating levels of 5α-DHT about 10% of those of testosterone, and approximately 0.3% of testosterone is converted into estradiol by aromatase.[2][151][157][158] 5α-Reductase is highly expressed in the male reproductive organs (including the prostate gland, seminal vesicles, and epididymides),[159] skin, hair follicles, and brain[160] and aromatase is highly expressed in adipose tissue, bone, and the brain.[161][162] As much as 90% of testosterone is converted into 5α-DHT in so-called androgenic tissues with high 5α-reductase expression,[152] and due to the several-fold greater potency of 5α-DHT as an AR agonist relative to testosterone,[163] it has been estimated that the effects of testosterone are potentiated 2- to 3-fold in such tissues.[164]
Levels[edit]
Total levels of testosterone in the body are 264 to 916 ng/dL in men age 19 to 39 years,[165] while mean testosterone levels in adult men have been reported as 630 ng/dL.[166] Levels of testosterone in men decline with age.[165] In women, mean levels of total testosterone have been reported to be 32.6 ng/dL.[167][168] In women with hyperandrogenism, mean levels of total testosterone have been reported to be 62.1 ng/dL.[167][168]
Testosterone levels in males and females show
Total testosterone levels in males throughout life show
Reference ranges for blood tests, showing adult male testosterone levels in light blue at center-left.
Measurement[edit]
Testosterone’s bioavailable concentration is commonly determined using the Vermeulen calculation or more precisely using the modified Vermeulen method,[174][175] which considers the dimeric form of sex-hormone-binding-globulin.[176]
Both methods use chemical equilibrium to derive the concentration of bioavailable testosterone: in circulation testosterone has two major binding partners, albumin (weakly bound) and sex-hormone-binding-globulin (strongly bound). These methods are described in detail in the accompanying figure.
Dimeric sex-hormone-binding-globulin with its testosterone ligands
Two methods for determining concentration of bioavailable testosterone.
History[edit]
A testicular action was linked to circulating blood fractions – now understood to be a family of androgenic hormones – in the early work on castration and testicular transplantation in fowl by Arnold Adolph Berthold (1803–1861).[177] Research on the action of testosterone received a brief boost in 1889, when the Harvard professor Charles-Édouard Brown-Séquard (1817–1894), then in Paris, self-injected subcutaneously a "rejuvenating elixir" consisting of an extract of dog and guinea pig testicle. He reported in The Lancet that his vigor and feeling of well-being were markedly restored but the effects were transient,[178] and Brown-Séquard's hopes for the compound were dashed. Suffering the ridicule of his colleagues, he abandoned his work on the mechanisms and effects of androgens in human beings.
In 1927, the University of Chicago's Professor of Physiologic Chemistry, Fred C. Koch, established easy access to a large source of bovine testicles — the Chicago stockyards — and recruited students willing to endure the tedious work of extracting their isolates. In that year, Koch and his student, Lemuel McGee, derived 20 mg of a substance from a supply of 40 pounds of bovine testicles that, when administered to castrated roosters, pigs and rats, remasculinized them.[179] The group of Ernst Laqueur at the University of Amsterdam purified testosterone from bovine testicles in a similar manner in 1934, but isolation of the hormone from animal tissues in amounts permitting serious study in humans was not feasible until three European pharmaceutical giants—Schering (Berlin, Germany), Organon (Oss, Netherlands) and Ciba (Basel, Switzerland)—began full-scale steroid research and development programs in the 1930s.
Nobel Prize winner, Leopold Ruzicka of Ciba, a pharmaceutical industry giant that synthesized testosterone.
The Organon group in the Netherlands were the first to isolate the hormone, identified in a May 1935 paper "On Crystalline Male Hormone from Testicles (Testosterone)".[180] They named the hormone testosterone, from the stems of testicle and sterol, and the suffix of ketone. The structure was worked out by Schering's Adolf Butenandt, at the Chemisches Institut of Technical University in Gdańsk.[181][182]
The chemical synthesis of testosterone from cholesterol was achieved in August that year by Butenandt and Hanisch.[183] Only a week later, the Ciba group in Zurich, Leopold Ruzicka (1887–1976) and A. Wettstein, published their synthesis of testosterone.[184] These independent partial syntheses of testosterone from a cholesterol base earned both Butenandt and Ruzicka the joint 1939 Nobel Prize in Chemistry.[182][185] Testosterone was identified as 17β-hydroxyandrost-4-en-3-one (C19H28O2), a solid polycyclic alcohol with a hydroxyl group at the 17th carbon atom. This also made it obvious that additional modifications on the synthesized testosterone could be made, i.e., esterification and alkylation.
The partial synthesis in the 1930s of abundant, potent testosterone esters permitted the characterization of the hormone's effects, so that Kochakian and Murlin (1936) were able to show that testosterone raised nitrogen retention (a mechanism central to anabolism) in the dog, after which Allan Kenyon's group[186] was able to demonstrate both anabolic and androgenic effects of testosterone propionate in eunuchoidal men, boys, and women. The period of the early 1930s to the 1950s has been called "The Golden Age of Steroid Chemistry",[187] and work during this period progressed quickly. Research in this golden age proved that this newly synthesized compound—testosterone—or rather family of compounds (for many derivatives were developed from 1940 to 1960), was a potent multiplier of muscle, strength, and well-being.[188]
Other animals[edit]
Testosterone is observed in most vertebrates. Testosterone and the classical nuclear androgen receptor first appeared in gnathostomes (jawed vertebrates).[189] Agnathans (jawless vertebrates) such as lampreys do not produce testosterone but instead use androstenedione as a male sex hormone.[190] Fish make a slightly different form called 11-ketotestosterone.[191] Its counterpart in insects is ecdysone.[192] The presence of these ubiquitous steroids in a wide range of animals suggest that sex hormones have an ancient evolutionary history.[193]
Abstract
To understand the evolutionary significance of geographic variation, one must identify the factors that generate phenotypic differences among populations. I examined the causes of geographic variation in and evolutionary history of number of trunk vertebrae in slender salamanders. Batrachoseps (Caudata: Plethodontidae). Number of trunk vertebrae varies at many taxonomic levels within Batrachoseps. Parallel clines in number occur along an environmental gradient in three lineages in the Coast Ranges of California. These parallel clines may signal either adaptation or a shared phenotypically plastic response to the environmental gradient. By raising eggs from 10 populations representing four species of Batrachoseps, I demonstrated that number of trunk vertebrae can be altered by the developmental temperature; however, the degree of plasticity is insufficient to account for geographic variation. Thus, the geographic variation results largely from genetic variation. Number of trunk vertebrae covaries with body size and shape in diverse vertebrate taxa, including Batrachoseps. I hypothesize that selection for different degrees of elongation, possibly related to fossoriality, has led to the extensive evolution of number of trunk vertebrae in Batrachoseps. Analysis of intrapopulational variation revealed sexual dimorphism in both body shape and number of trunk vertebrae, but no correlation between these variables in either sex. Females are more elongate than males, a pattern that has been attributed to fecundity selection in other taxa. Patterns of covariation among different classes of vertebrae suggest that some intrapopulational variation in number results from changes in vertebral identity rather than changes in segmentation.
Elizabeth L. Jockusch
Evolution
Images in this gallery were captured by:
Mark Smith M.S. Geoscientist mark@macroscopicsolutions.com
Daniel Saftner B.S. Geoscientist and Returned Peace Corps Volunteer daniel@macroscopicsolutions.com
Annette Evans Ph.D. Student at the University of Connecticut annette@macroscopicsolutions.com
Rapid strata formation in soft sand (field evidence).
Photo of strata formation in soft sand on a beach, created by tidal action of the sea.
Formed in a single, high tidal event. Stunning evidence which displays multiple strata/layers.
Why this is so important ....
It has long been assumed, ever since the 17th century, that layers/strata observed in sedimentary rocks were built up gradually, layer upon layer, over many years. It certainly seemed logical at the time, from just looking at rocks, that lower layers would always be older than the layers above them, i.e. that lower layers were always laid down first followed, in time, by successive layers on top.
This was assumed to be true and became known as the superposition principle.
It was also assumed that a layer comprising a different material from a previous layer, represented a change in environmental conditions/factors.
These changes in composition of layers or strata were considered to represent different, geological eras on a global scale, spanning millions of years. This formed the basis for the Geologic Column, which is used to date rocks and also fossils. The evolutionary, 'fossil record' was based on the vast ages and assumed geological eras of the Geologic Column.
There was also circular reasoning applied with the assumed age of 'index' fossils (based on evolutionary beliefs & preconceptions) used to date strata in the Geologic Column. Dating strata from the assumed age of (index) fossils is known as Biostratigraphy.
We now know that, although these assumptions seemed logical, they are not supported by the evidence.
At the time, the mechanics of stratification were not properly known or studied.
An additional factor was that this assumed superposition and uniformitarian model became essential, with the wide acceptance of Darwinism, for the long ages required for progressive microbes-to-human evolution. There was no incentive to question or challenge the superposition, uniformitarian model, because the presumed, fossil 'record' had become dependant on it, and any change in the accepted model would present devastating implications for Darwinism.
This had the unfortunate effect of linking the study of geology so closely to Darwinism, that any study independent of Darwinian considerations was effectively stymied. This link of geology with Darwinian preconceptions is known as biostratigraphy.
Some other field evidence can be observed here: www.flickr.com/photos/101536517@N06/sets/72157635944904973/
and also in the links to stunning, experimental evidence, carried out by sedimentologists, given later.
_______________________________________________
GEOLOGIC PRINCIPLES (established by Nicholas Steno in the 17th Century):
What Nicolas Steno believed about strata formation is the basis of the principle of Superposition and the principle of Original Horizontality.
dictionary.sensagent.com/Law_of_superposition/en-en/
“Assuming that all rocks and minerals had once been fluid, Nicolas Steno reasoned that rock strata were formed when particles in a fluid such as water fell to the bottom. This process would leave horizontal layers. Thus Steno's principle of original horizontality states that rock layers form in the horizontal position, and any deviations from this horizontal position are due to the rocks being disturbed later.”)
BEDDING PLANES.
'Bedding plane' describes the surface in between each stratum which are formed during sediment deposition.
science.jrank.org/pages/6533/Strata.html
“Strata form during sediment deposition, that is, the laying down of sediment. Meanwhile, if a change in current speed or sediment grain size occurs or perhaps the sediment supply is cut off, a bedding plane forms. Bedding planes are surfaces that separate one stratum from another. Bedding planes can also form when the upper part of a sediment layer is eroded away before the next episode of deposition. Strata separated by a bedding plane may have different grain sizes, grain compositions, or colours. Sometimes these other traits are better indicators of stratification as bedding planes may be very subtle.”
______________________________________________
Several catastrophic events, flash floods, volcanic eruptions etc. have forced Darwinian, influenced geologists to admit to rapid stratification in some instances. However they claim it is a rare phenomenon, which they have known about for many years, and which does nothing to invalidate the Geologic Column, the fossil record, evolutionary timescale, or any of the old assumptions regarding strata formation, sedimentation and the superposition principle. They fail to face up to the fact that rapid stratification is not an extraordinary phenonemon, but rather the prevailing and normal mechanism of sedimentary deposition whenever and wherever there is moving, sediment-laden water. The experimental evidence demonstrates the mechanism and a mass of field evidence in normal (non-catastrophic) conditions shows it is a normal everyday occurrence.
It is clear from the experimental evidence that the usual process of stratification is - that strata are not formed by horizontal layers being laid on top of each other in succession, as was assumed. But by sediment being sorted in the flowing water and laid down diagonally in the direction of flow. See diagram:
www.flickr.com/photos/truth-in-science/39821536092/in/dat...
The field evidence (in the image) presented here - of rapid, simultaneous stratification refutes the Superposition Principle and the Principle of Lateral Continuity.
We now know, the Superposition Principle only applies on a rare occasion where sedimentary deposits are laid down in still water.
Superposition is required for the long evolutionary timescale, but the evidence shows it is not the general rule, as was once believed. Most sediment is laid down in moving water, where particle segregation is the general rule, resulting in the simultaneous deposition of strata/layers as shown in the photo.
See many other examples of rapid stratification (with geological features): www.flickr.com/photos/101536517@N06/sets/72157635944904973/
Rapid, simultaneous formation of layers/strata, through particle segregation in moving water, is so easily created it has even been described by sedimentologists (working on flume experiments) as a law ...
"Upon filling the tank with water and pouring in sediments, we immediately saw what was to become the rule: The sediments sorted themselves out in very clear layers. This became so common that by the end of two weeks, we jokingly referred to Andrew's law as "It's difficult not to make layers," and Clark's law as "It's easy to make layers." Later on, I proposed the "law" that liquefaction destroys layers, as much to my surprise as that was." Ian Juby, www.ianjuby.org/sedimentation/
The example in the photo is the result of normal, everyday tidal action in a single incident. Where the water current or movement is more turbulent, violent, or catastrophic, great depths (many metres) of stratified sediment can be laid down in a short time. Certainly not the many millions of years assumed by evolutionists.
The composition of strata formed in any deposition event. is related to whatever materials are in the sediment mix, not to any particular timescale. Whatever is in the mix will be automatically sorted into strata/layers. It could be sand, or other material added from mud slides, erosion of chalk deposits, coastal erosion, volcanic ash etc. Any organic material (potential fossils), alive or dead, engulfed by, or swept into, a turbulent sediment mix, will also be sorted and buried within the rapidly, forming layers.
See many other examples of rapid stratification with geological features: www.flickr.com/photos/101536517@N06/sets/72157635944904973/
Stratified, soft sand deposit. demonstrates the rapid, stratification principle.
Important, field evidence which supports the work of the eminent, sedimentologist Dr Guy Berthault MIAS - Member of the International Association of Sedimentologists.
(Dr Berthault's experiments (www.sedimentology.fr/)
And also the experimental work of Dr M.E. Clark (Professor Emeritus, U of Illinois @ Urbana), Andrew Rodenbeck and Dr. Henry Voss, (www.ianjuby.org/sedimentation/)
Location: Sandown, Isle of Wight. Formed 18/02/2018, This field evidence demonstrates that multiple strata in sedimentary deposits do not need millions of years to form and can be formed rapidly. This natural example confirms the principle demonstrated by the sedimentation experiments carried out by Dr Guy Berthault and other sedimentologists. It calls into question the standard, multi-million year dating of sedimentary rocks, and the dating of fossils by depth of burial or position in the strata.
Mulltiple strata/layers are evident in this example.
Dr Berthault's experiments (www.sedimentology.fr/) and other experiments (www.ianjuby.org/sedimentation/) and field studies of floods and volcanic action show that, rather than being formed by gradual, slow deposition of sucessive layers superimposed upon previous layers, with the strata or layers representing a particular timescale, particle segregation in moving water or airborne particles can form strata or layers very quickly, frequently, in a single event.
And, most importantly, lower strata are not older than upper strata, they are the same age, having been created in the same sedimentary episode.
Such field studies confirm experiments which have shown that there is no longer any reason to conclude that strata/layers in sedimentary rocks relate to different geological eras and/or a multi-million year timescale. www.youtube.com/watch?v=5PVnBaqqQw8&feature=share&.... they also show that the relative position of fossils in rocks is not indicative of an order of evolutionary succession. Obviously, the uniformitarian principle, on which the geologic column is based, can no longer be considered valid. And the multi-million, year dating of sedimentary rocks and fossils needs to be reassessed. Rapid deposition of stratified sediments also explains the enigma of polystrate fossils, i.e. large fossils that intersect several strata. In some cases, tree trunk fossils are found which intersect the strata of sedimentary rock up to forty feet in depth. upload.wikimedia.org/wikipedia/commons/thumb/0/08/Lycopsi... They must have been buried in stratified sediment in a short time (certainly not millions, thousands, or even hundreds of years), or they would have rotted away. youtu.be/vnzHU9VsliQ
In fact, the vast majority of fossils are found in good, intact condition, which is testament to their rapid burial. You don't get good fossils from gradual burial, because they would be damaged or destroyed by decay, predation or erosion. The existence of so many fossils in sedimentary rock on a global scale is stunning evidence for the rapid depostion of sedimentary rock as the general rule. It is obvious that all rock containing good intact fossils was formed from sediment laid down in a very short time, not millions, or even thousands of years.
See set of photos of other examples of rapid stratification: www.flickr.com/photos/101536517@N06/sets/72157635944904973/
Carbon dating of coal should not be possible if it is millions of years old, yet significant amounts of Carbon 14 have been detected in coal and other fossil material, which indicates that it is less than 50,000 years old. www.ldolphin.org/sewell/c14dating.html
www.grisda.org/origins/51006.htm
Evolutionists confidently cite multi-million year ages for rocks and fossils, but what most people don't realise is that no one actually knows the age of sedimentary rocks or the fossils found within them. So how are evolutionists so sure of the ages they so confidently quote? The astonishing thing is they aren't. Sedimentary rocks cannot be dated by radiometric methods*, and fossils can only be dated to less than 50,000 years with Carbon 14 dating. The method evolutionists use is based entirely on assumptions. Unbelievably, fossils are dated by the assumed age of rocks, and rocks are dated by the assumed age of fossils, that's right ... it is known as circular reasoning.
* Regarding the radiometric dating of igneous rocks, which is claimed to be relevant to the dating of sedimentary rocks, in an occasional instance there is an igneous intrusion associated with a sedimentary deposit -
Prof. Aubouin says in his Précis de Géologie: "Each radioactive element disintegrates in a characteristic and constant manner, which depends neither on the physical state (no variation with pressure or temperature or any other external constraint) nor on the chemical state (identical for an oxide or a phosphate)."
"Rocks form when magma crystallizes. Crystallisation depends on pressure and temperature, from which radioactivity is independent. So, there is no relationship between radioactivity and crystallisation.
Consequently, radioactivity doesn't date the formation of rocks. Moreover, daughter elements contained in rocks result mainly from radioactivity in magma where gravity separates the heavier parent element, from the lighter daughter element. Thus radiometric dating has no chronological signification." Dr. Guy Berthault www.sciencevsevolution.org/Berthault.htm
Visit the fossil museum:
www.flickr.com/photos/101536517@N06/sets/72157641367196613/
Just how good are peer reviews of scientific papers?
www.sciencemag.org/content/342/6154/60.full
www.examiner.com/article/want-to-publish-science-paper-ju...
The neo-Darwinian idea that the human genome consists entirely of an accumulation of billions of mutations is, quite obviously, completely bonkers. Nevertheless, it is compulsorily taught in schools and universities as 'science'.
FIST BUMP: content.time.com/time/nation/article/0,8599,1812102,00.html
It's a hand gesture normally associated with sporting events and Bud Lite commercials. But on Tuesday night, millions of people witnessed Michelle Obama daintily knocking knuckles with her husband as the Illinois Senator took the stage to claim the 2008 Democratic presidential nomination. The Washington Post called it "the fist bump heard 'round the world."
The origins of the bump are murky, though most communication experts agree on a basic — if fuzzy — evolutionary timeline: the handshake (which itself dates back to ancient times) begat the "gimme-five" palm slap that later evolved into the now universal "high-five" and, finally, the fist bump.
Some claim the act of knuckle-bumping began in the 1970s with NBA players like Baltimore Bullets guard Fred Carter. Others claim the fist bump's national debut occurred off the court, citing the Wonder Twins, minor characters in the 1970s Hanna-Barbera superhero cartoon The Superfriends, who famously touched knuckles and cried "Wonder Twin powers, activate!' before morphing into animals or ice sculptures. One might also credit germaphobics for the fist bump's popularity. Deal or No Deal host Howie Mandel reportedly adopted the gesture as a friendly way to avoid his contestants' germs.
Even the terminology used to describe the manual move is under dispute. On reporting Obama's speech, The New York Times described it stuffily as a "closed-fisted high-five" while Human Events reader racily suggested it was closer to "Hezbollah-style fist-jabbing," (the comment was later removed from the article). One Internet poster even referred to it as "the fist bump of hope." Other terms for the move include "power five," "fist pound," "knuckle bump," "Quarter Pounder" and "dap."
The fist bump's precursor, the low- and high-fives, originated in the 1950s, again mostly among athletes, who deemed handshakes too muted and formal for celebrating teamwork and triumph. The 1980s are generally regarded as the heyday of the high-five, though the gesture has enjoyed a revival of sorts in recent years — especially among Gen-X parents and their offspring. Modern-day high-five enthusiasts have even created a cellphone version: Callers high-five their phones (slap the speakers) or simultaneously type "5."
The problem with the high-five is that it can occasionally be hard to pull off. Just ask Tiger Woods and his caddie, who botched a high-five on national TV during the 2005 U.S. Masters Golf Tournament. Perhaps this is what makes the fist bump so unique. Though simple in motion, its meaning is far more complicated. In any other context, a clenched fist would be perceived as hostile.
Ambiguities aside, most pundits and observers alike had complimentary words for the Obama family's fist bump, seeing it as a rare moment of spontaneity and playfulness that a race already in its 17th month sorely needed.
"Gestures, particularly ones that are recent, haven't been studied that much," says David Givens, director of the Center for Nonverbal Studies in Spokane, Wash. "For me, it's ironic because we all noticed that fist bump. I thought it was very touching. It was an elegant little non-verbal moment and it gave us a view into their relationship."
For his part, Obama, who once likened himself to NBA star LeBron James, said the fist bump reflects a marriage that keeps him grounded. "It captures what I love about my wife," he later explained to NBC's Brian Williams. "That for all the hoopla I'm her husband and sometimes we'll do silly things."
Though National High-Five Day already exists — the third Thursday in April every year — the fist bump has yet to claim its own day on the calendar. June 3rd might be a good candidate.
HIGH-FIVE:
mentalfloss.com/article/50163/brief-history-high-five
Since 2002, the third Thursday of April is recognized as National High Five Day—a 24-hour period for giving familiars and strangers alike as many high fives as humanly possible. A few University of Virginia students invented the day, which has since evolved into a “High 5-A-Thon” that raises money each year for cancer research. Here are a few more facts to get you in the celebrating spirit.
UP HIGH
That may sound like a lot of celebration for a simple hand gesture, but the truth is, the act of reaching your arm up over your head and slapping the elevated palm and five fingers of another person has revolutionized the way Americans (and many all over world) cheer for everything from personal achievements to miraculous game-winning plays in the sports world. Psychological studies on touch and human contact have found that gestures like the high five enhance bonding among sports teammates, which in turn has a winning effect on the whole team. Put 'er there!
DOWN LOW
There is some dispute about who actually invented the high five. Some claim the gesture was invented by Los Angeles Dodgers outfielder Glenn Burke when he spontaneously high-fived fellow outfielder Dusty Baker after a home run during a game in 1977. Others claim the 1978-79 Louisville basketball team started it on the court. Since no one could definitively pinpoint the exact origin, National High Five Day co-founder Conor Lastowka made up a story about Murray State basketballer Lamont Sleets inventing it in the late '70s/early '80s, inspired by his father's Vietnam unit, “The Fives.”
Regardless of which high-five origin story is more accurate, there is little question of its roots. The high five evolved from its sister-in-slappage, the low five. The gesture, also known as “slapping skin,” was made popular in the jazz age by the likes of Al Jolson, Cab Calloway and the Andrews Sisters.
GIMME FIVE
As the high five has evolved over the past few decades, variations have developed and become popular in and of themselves. Here are five popular styles:
The Baby Five
Before most babies learn to walk or talk, they learn to high five. Baby hands are much smaller than adult hands, so grownups have to either use one finger, scrunch their fingers together or flat-out palm it.
The Air Five
Also known as the "wi-five" in the more recent technology age, this one is achieved just like a regular high five, minus the hand-to-hand contact. Its great for germaphobes and long distance celebrations.
The Double High Five
Also known as a “high ten,” it is characterized by using both hands simultaneously to high five.
The Fist Bump
It's a trendy off-shoot of the high five that made headlines thanks to a public display by the U.S. President and First Lady. Instead of palm slapping, it involves contact between the knuckles of two balled fists. In some cases, the fist bump can be “exploding,” by which the bump is followed by a fanning out of all involved fingers.
The Self High Five
If something awesome happens and there's no one else around, the self high five may be appropriate. It happens when one person raises one hand and brings the other hand up to meet it, high-five style. Pro-wrestler Diamond Dallas Page made the move famous in his appearances at WCW matches.
YOU'RE TOO SLOW!
Don't fall for that old joke. The key to a solid high five is threefold. Always watch for the elbow of your high-fiving mate to ensure accuracy; never leave a buddy hanging; and always have hand sanitizer on you. Have a Happy High Five Day!
The Manchester Museum, Oxford Road, Manchester, Greater Manchester.
The museum's first collections were assembled by the Manchester Society of Natural History formed in 1821 with the purchase of the collection of John Leigh Philips. In 1850 the collections of the Manchester Geological Society were added. By the 1860s both societies encountered financial difficulties and, on the advice of the evolutionary biologist Thomas Huxley, Owens College (now the University of Manchester) accepted responsibility for the collections in 1867. The museum in Peter Street was sold in 1875 after Owens College moved to new buildings in Oxford Street.
The college commissioned Alfred Waterhouse, architect of London's Natural History Museum, to design a museum to house the collections for the benefit of students and the public on a site in Oxford Road (then Oxford Street). The Manchester Museum was opened to the public in 1888. At the time, the scientific departments of the college were immediately adjacent, and students entered the galleries from their teaching rooms in the Beyer Building.
Two subsequent extensions mirror the development of its collections. The 1912 pavilion was largely funded by Jesse Haworth, a textile merchant, to house the archaeological and Egyptological collections acquired through excavations he had supported. The 1927 extension was built to house the ethnographic collections. The Gothic Revival street frontage which continues to the Whitworth Hall has been ingeniously integrated by three generations of the Waterhouse family. When the adjacent University Dental Hospital of Manchester moved to a new site, its old building was used for teaching and subsequently occupied by the museum.
The museum is one of the University of Manchester's 'cultural assets', along with the Whitworth Art Gallery, John Rylands Library, Jodrell Bank visitor centre and others.
Information Source:
Killyleagh Castle, Northern Ireland
The European lute and the modern Near-Eastern oud descend from a common ancestor via diverging evolutionary paths. The lute is used in a great variety of instrumental music from the Medieval to the late Baroque eras and was the most important instrument for secular music in the Renaissance.
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
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.
Stratified, soft sand deposit. demonstrates the rapid stratification principle.
Photo of strata formation in soft sand on a beach, created by tidal action of the sea.
This distance photo shows the context, see close up photo here: www.flickr.com/photos/truth-in-science/30349004783
Rapidly deposited, sandbank with geological features of sedimentary rock, i.e. strata, folded strata and faulting. Formed in a single, tidal event of turbulent, high tide with gale force winds.
Rapid stratification. Field evidence.
Location: Sandown beach, Isle of Wight. Formed on 17/11/2016, Overall depth of deposit: approx 20 inches.
This field evidence demonstrates that multiple strata in sedimentary deposits do not need millions of years to form and can be formed rapidly. This natural example confirms the principle demonstrated by the sedimentation experiments carried out by Dr Guy Berthault and other sedimentologists. It calls into question the standard, multi-million year dating of sedimentary rocks, and the dating of fossils by depth of burial or position in the strata.
Strata lines/layers are clearly visible in this photo.
Dr Berthault's experiments (sedimentology.fr/) and other experiments (ianjuby.org/sedimentation/) and field studies of floods and volcanic action show that, rather than being formed by gradual, slow deposition of sediment, with the strata or layers representing a timescale or even a particular, environmental epoch, particle segregation in moving water or airborne particles can form strata or layers very quickly. Such field studies and the experiments show that there is no longer any reason to conclude that strata in sedimentary rocks relate to different geological eras and/or a multi-million year timescale. www.youtube.com/watch?v=5PVnBaqqQw8&feature=share&.... It also shows that the relative position of fossils in rocks is not indicative of an order of evolutionary succession. Obviously, the uniformitarian principle, on which the geologic column is based, can no longer be considered valid. And the multi-million, year dating of sedimentary rocks and fossils needs to be reassessed. Rapid deposition of stratified sediments also explains the enigma of polystrate fossils, i.e. large fossils that intersect several strata. In some cases, tree trunk fossils are found which intersect the strata of sedimentary rock up to forty feet in depth. upload.wikimedia.org/wikipedia/commons/thumb/0/08/Lycopsi... They must have been buried in stratified sediment in a short time (certainly not millions or even thousands of years), or they would have rotted away. youtu.be/vnzHU9VsliQ
See set of photos of another example of rapid stratification: www.flickr.com/photos/101536517@N06/sets/72157635944904973/
Carbon dating of coal should not be possible if it is millions of years old, yet significant amounts of Carbon 14 have been detected in coal and other fossil material, which indicates that it is less than 50,000 years old. www.ldolphin.org/sewell/c14dating.html
www.grisda.org/origins/51006.htm
Evolutionists confidently cite multi-million year ages for rocks and fossils, but what most people don't realise is that no one actually knows the age of sedimentary rocks or the fossils found within them. So how are evolutionists so sure of the ages they so confidently quote? The astonishing thing is they aren't. Sedimentary rocks cannot be dated by radiometric methods, and fossils can only be dated to less than 50,000 years with Carbon 14 dating. The method evolutionists use is based entirely on assumptions. Unbelievably, fossils are dated by the assumed age of rocks, and rocks are dated by the assumed age of fossils, that's right ... it is known as circular reasoning.
www.nhm.ac.uk/nature-online/science-of-natural-history/th...
Visit the fossil museum:
www.flickr.com/photos/101536517@N06/sets/72157641367196613/
Just how good are peer reviews of scientific papers?
www.sciencemag.org/content/342/6154/60.full
www.examiner.com/article/want-to-publish-science-paper-ju...
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.
Evolutionary Loop 517, a monumental six-metre bronze sculpture by the London-based contemporary artist, Nasser Azam, will be unveiled on the 27th May at the University of Aberdeen. The sculpture was commissioned for the Sir Duncan Rice Library, and is a new defining landmark for the University campus. The Library was officially opened in September 2012 by Her Majesty Queen Elizabeth, and the Duke of Edinburgh.
Azam worked closely with the architect of the library, Morten Schmidt, a founding Partner of the award-winning Scandinavian architectural practice schmidt/hammer/lassen architects, who have designed some of Europe’s most ground breaking library buildings. The sculptural forms of Evolutionary Loop 517 thus establish a strong rapport with the surrounding buildings and landscape. Azam commented: “The project has been most rewarding as I was involved with the architects from the outset.Evolutionary Loop 517 to me reflects the visually striking interior design of the library and the use of bronze cements a strong connectivity between the historic relevance and traditions of the university, and the bold and beautiful statement of the contemporary library building.”
The sculpture was named following a competition launched by Aberdeen University, in collaboration with the artist. The winning entry came from Chemistry Professor Marcel Jaspars, who explained his choice: “I came up with the name as I felt this is a very organic piece, and the intertwined forms connect in a loop, which reminded me of the evolutionary process, with continuous change and connection. It reflects the fact that students, academics and staff are constantly evolving in their experiences and connections at the University of Aberdeen, to show the organic nature of the sculpture in symbiosis with the research carried out at the University and to represent the age of the University when this sculpture was made. In a diverse way, we will all have a connection with the University of Aberdeen just by looking at the sculpture. In future years, maybe people will simply say ’Let’s meet at the Loop’.”
Chris Banks, Aberdeen University Librarian and Director of Library Special Collections and Museums, commented: “I am thrilled that the sculpture is now taking pride of place in front of the library. We are extremely grateful to the donor who commissioned the piece and to Nasser who has created this stunning piece of art for us.”
The £57 million Sir Duncan Rice Library provides an advanced learning environment in which the latest learning technology adds value to a magnificent collection of over one million books and journals. It also safeguards the University’s internationally-significant archive of historic books, manuscripts and works of art within the Special Collection Centre and Loop provides another important addition to these collections. The Library is not only a magnificent and inspirational building – it is a hugely important institutional and regional asset which will benefit students, scholars and communities for decades to come.
Alongside the sculpture, Azam has finished a large painting, titled Loop, reflecting on the relationship between sculpture and architecture. Loop has entered the collection of the University, and will be hung in the new library building.
Other major commissions of Nasser Azam’s career to date include the sculpture Athena, commissioned for the entrance to London City Airport, and unveiled on 5th July 2012 to coincide with the 2012 London Olympics. Athena is the UK’s tallest bronze sculpture. Azam also created the large bronze sculpture The Dance, unveiled on the South Bank on 21 February 2008, as well as work for the National Botanic Gardens of Ireland, in Dublin.
Between 2008 and 2010 he participated in a number of high-profile ‘Performance painting’ projects including; Life In Space, a project that took place on board a Russian parabolic aircraft, where he completed two triptychs as an homage to Francis Bacon in zero gravity; and the widely reported Antarctica project, where the artist endured severe weather conditions, to create a series of large oil canvases on an ice desert of the frozen Tundra. Nasser Azam was born in Pakistan in 1963 and spent several years in Japan, before settling in London where he has a studio. He has projects coming up in New York, London and Rio de Janeiro.
NOTES TO EDITORS
Founded in 1495, the University of Aberdeen is one of the UK’s most internationally distinguished ancient universities. It has a student population of around 16,000 and a large international community of students drawn from 120 different countries. The University, which is Scotland’s third oldest, is at the forefront of teaching, learning and discovery, as it has been for over 500 years. As the ‘global university of the north’, it has consistently sent pioneers and ideas outward to every part of the world. Aberdeen is an ambitious, research-driven university with a global outlook, committed to excellence in everything it does. It is committed to providing excellent support services and facilities and has made an unprecedented multi-million pound investment to provide its students with some of the very best facilities available in the UK including the Sir Duncan Rice Library.
TIMINGS AND LOCATION OF UNVEILING
The unveiling of the sculpture will take place on 27th May will be between 11am-1pm
The address of the Library is: The Sir Duncan Rice Library, University of Aberdeen,
A very peaceful evening by Poole Harbour. Such a standard shot but it doesn't stop it being a beautiful scene and mood.
I have been considering the evolutionary causes for our appreciation of beauty. Some aspect are pretty obvious: a beautiful woman (for a male*), recognisably feminine, young, healthy and smiling is obviously a good potential mate; a beautiful landscape, with a river or coast, trees and lush vegetation, a view of the surroundings, mountains in the background, is a good place to make a home. But it took me a while to figure out why a sunset is beautiful and provokes a feeling of peace.
I have realised that for our ancestors, daytime was a constant struggle to get food and compete with rivals and predators and survive, but night time is when you retreat into a safe place and sleep – so sunset is a signal to stop work, be with your companions and relax. This makes the orange light and the sun on the horizon a natural tranquilliser. And a universally popular subject for photography.
*It also took me a while to undertand why feminine beauty is also appreciated by women (more than male "beauty"). I think it is because biologically males can afford to pass on their genes with any females who look like they will co-operate (or even if not) whereas for females with a limited number of offspring, their choice of mate will be focussed on the individual survival of each child, requiring a mate who is healthy, effective, at least moderately dominant and therefore able to provide for, and defend the family – and also romantic enough to fall in love with them and stay around in difficult times (especially pregnancy). So personality rather than appearance is the better guide. But as our male and female genes are mostly shared, men share the female appreciation of reliable personality factors and women share the male visual appreciation of female beauty – explaining why womens' magazines almost all have beautiful women the covers.
This ultimate evolutionary stage of the 928 model series combines wide wings with a spoiler and a band of taillights in a very distinct silhouette.
Its sporty look goes hand in hand with the increased engine capacity, underscoring its affinity with the Gran Turismo class in motorsports.
The 928 proves to be ideal as a comfortable touring car for long trips.
5.397 cc
V8
350 PS
Vmax : 275 km/h
Techno Classica 2016
Essen
Deutschland - Germany
April 2016
Greetings mate! As many of you know, I love marrying art, science, and math in my fine art portrait and landscape photography!
The 45surf and gold 45 revolver swimsuits, shirts, logos, designs, and lingerie are designed in accordance with the golden ratio! More about the design and my philosophy of "no retouching" on the beautiful goddesses in my new book:
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"Photographing Women Models: Portrait, Swimsuit, Lingerie, Boudoir, Fine Art, & Fashion Photography Exalting the Venus Goddess Archetype"
If you would like a free review copy, message me!
Epic Landscape Photography! New Book!
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And here's more on the golden ratio which appears in many of my landscape and portrait photographs (while shaping the proportions of the golden gun)!
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The dx4/dt=ic above the gun on the lingerie derives from my new physics books devoted to Light, Time, Dimension Theory!
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Thanks for being a fan! Would love to hears your thoughts on my philosophies and books! :)
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Beautiful swimsuit bikini model goddess!
Golden Ratio Lingerie Model Goddess LTD Theory Lingerie dx4/dt=ic! The Birth of Venus, Athena, and Artemis! Girls and Guns!
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I am working on several books on "epic photography," and I recently finished a related one titled: The Golden Number Ratio Principle: Why the Fibonacci Numbers Exalt Beauty and How to Create PHI Compositions in Art, Design, & Photography: An Artistic and Scientific Introduction to the Golden Mean . Message me on facebook for a free review copy!
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The Golden Ratio informs a lot of my art and photographic composition. The Golden Ratio also informs the design of the golden revolver on all the swimsuits and lingerie, as well as the 45surf logo! Not so long ago, I came up with the Golden Ratio Principle which describes why The Golden Ratio is so beautiful.
The Golden Number Ratio Principle: Dr. E’s Golden Ratio Principle: The golden ratio exalts beauty because the number is a characteristic of the mathematically and physically most efficient manners of growth and distribution, on both evolutionary and purely physical levels. The golden ratio ensures that the proportions and structure of that which came before provide the proportions and structure of that which comes after. Robust, ordered growth is naturally associated with health and beauty, and thus we evolved to perceive the golden ratio harmonies as inherently beautiful, as we saw and felt their presence in all vital growth and life—in the salient features and proportions of humans and nature alike, from the distribution of our facial features and bones to the arrangements of petals, leaves, and sunflowers seeds. As ratios between Fibonacci Numbers offer the closest whole-number approximations to the golden ratio, and as seeds, cells, leaves, bones, and other physical entities appear in whole numbers, the Fibonacci Numbers oft appear in nature’s elements as “growth’s numbers.” From the dawn of time, humanity sought to salute their gods in art and temples exalting the same proportion by which all their vital sustenance and they themselves had been created—the golden ratio.
The Birth of Venus! Beautiful Golden Ratio Swimsuit Bikini Model Goddess! Helen of Troy! She was tall, thin, fit, and quite pretty!
Read all about how classical art such as The Birth of Venus inspires all my photography!
www.facebook.com/Photographing-Women-Models-Portrait-Swim...
"Photographing Women Models: Portrait, Swimsuit, Lingerie, Boudoir, Fine Art, & Fashion Photography Exalting the Venus Goddess Archetype"
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word slug is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semi-slugs (this is in contrast to the common name snail, which applies to gastropods that have a coiled shell large enough that they can fully retract their soft parts into it).
Various taxonomic families of land slugs form part of several quite different evolutionary lineages, which also include snails. Thus, the various families of slugs are not closely related, despite a superficial similarity in the overall body form. The shell-less condition has arisen many times independently as an example of convergent evolution, and thus the category "slug" is polyphyletic.
Taxonomy
Of the six orders of Pulmonata, two – the Onchidiacea and Soleolifera – solely comprise slugs. A third group, the Sigmurethra, contains various clades of snails, semi-slugs (i.e. snails whose shells are too small for them to retract fully into), and slugs.[1] The taxonomy of this group is in the process of being revised in light of DNA sequencing. It appears that pulmonates are paraphyletic and basal to the opisthobranchs, which are a terminal branch of the tree. The family Ellobiidae are also polyphyletic.
Subinfraorder Orthurethra
Superfamily Achatinelloidea Gulick, 1873
Superfamily Cochlicopoidea Pilsbry, 1900
Superfamily Partuloidea Pilsbry, 1900
Superfamily Pupilloidea Turton, 1831
Subinfraorder Sigmurethra
Superfamily Acavoidea Pilsbry, 1895
Superfamily Achatinoidea Swainson, 1840
Superfamily Aillyoidea Baker, 1960
Superfamily Arionoidea J.E. Gray in Turnton, 1840
Superfamily Athoracophoroidea
Family Athoracophoridae
Superfamily Orthalicoidea
Subfamily Bulimulinae
Superfamily Camaenoidea Pilsbry, 1895
Superfamily Clausilioidea Mörch, 1864
Superfamily Dyakioidea Gude & Woodward, 1921
Superfamily Gastrodontoidea Tryon, 1866
Superfamily Helicoidea Rafinesque, 1815
Superfamily Helixarionoidea Bourguignat, 1877
Superfamily Limacoidea Rafinesque, 1815
Superfamily Oleacinoidea H. & A. Adams, 1855
Superfamily Orthalicoidea Albers-Martens, 1860
Superfamily Plectopylidoidea Moellendorf, 1900
Superfamily Polygyroidea Pilsbry, 1894
Superfamily Punctoidea Morse, 1864
Superfamily Rhytidoidea Pilsbry, 1893
Family Rhytididae
Superfamily Sagdidoidera Pilsbry, 1895
Superfamily Staffordioidea Thiele, 1931
Superfamily Streptaxoidea J.E. Gray, 1806
Superfamily Strophocheiloidea Thiele, 1926
Superfamily Parmacelloidea
Superfamily Zonitoidea Mörch, 1864
Superfamily Quijotoidea Jesús Ortea and Juan José Bacallado, 2016
Family Quijotidae
Description
Tentacles: Like other pulmonate land gastropods, the majority of land slugs have two pairs of 'feelers' or tentacles on their head. The upper pair is light-sensing and has eyespots at the ends, while the lower pair provides the sense of smell. Both pairs are retractable in stylommatophoran slugs, but contractile in veronicellid slugs.
Mantle: On top of the slug, behind the head, is the saddle-shaped mantle. In stylommatophoran slugs, on the right-hand side of the mantle is a respiratory opening, the pneumostome, which is easier to see when open; also on the right side at the front are the genital opening and anus. Veronicellid slugs have a mantle covering the whole dorsal part of the body, they have no respiratory opening, and the anus opens posteriorly.
Tail: The part of a slug behind the mantle is called the 'tail'.
Keel: Some species of slugs, for example Tandonia budapestensis, have a prominent ridge running over their back along the middle of the tail (sometimes along the whole tail, sometimes only the posterior part).
Foot: The bottom side of a slug, which is flat, is called the 'foot'. Like almost all gastropods, a slug moves by rhythmic waves of muscular contraction on the underside of its foot. It simultaneously secretes a layer of mucus that it travels on, which helps prevent damage to the foot tissues. Around the edge of the foot in some slugs is a structure called the 'foot fringe'.
Vestigial shell: Most slugs retain a remnant of their shell, which is usually internalized. This organ generally serves as storage for calcium salts, often in conjunction with the digestive glands. An internal shell is present in the Limacidae and Parmacellidae. Adult Philomycidae, Onchidiidae and Veronicellidae lack shells.
Physiology
An active Ambigolimax slug in Fremont, California
Slugs' bodies are made up mostly of water and, without a full-sized shell, their soft tissues are prone to desiccation. They must generate protective mucus to survive. Many species are most active just after a rain because of the moist ground or during nighttime. In drier conditions, they hide in damp places such as under tree bark, fallen logs, rocks and manmade structures, such as planters, to help retain body moisture.[3] Like all other gastropods, they undergo torsion (a 180° twisting of the internal organs) during development. Internally, slug anatomy clearly shows the effects of this rotation—but externally, the bodies of slugs appear more or less symmetrical, except the pneumostome, which is on one side of the animal, normally the right-hand side.
Slugs produce two types of mucus: one is thin and watery, and the other thick and sticky. Both kinds are hygroscopic. The thin mucus spreads from the foot's centre to its edges, whereas the thick mucus spreads from front to back. Slugs also produce thick mucus that coats the whole body of the animal. The mucus secreted by the foot contains fibres that help prevent the slug from slipping down vertical surfaces.
The "slime trail" a slug leaves behind has some secondary effects: other slugs coming across a slime trail can recognise the slime trail as produced by one of the same species, which is useful in finding a mate. Following a slime trail is also part of the hunting behaviour of some carnivorous slugs. Body mucus provides some protection against predators, as it can make the slug hard to pick up and hold by a bird's beak, for example, or the mucus itself can be distasteful. Some slugs can also produce very sticky mucus which can incapacitate predators and can trap them within the secretion. Some species of slug, such as Limax maximus, secrete slime cords to suspend a pair during copulation.
Reproduction
Slugs are hermaphrodites, having both female and male reproductive organs. Once a slug has located a mate, they encircle each other and sperm is exchanged through their protruded genitalia. A few days later, the slugs lay approximately thirty eggs in a hole in the ground, or beneath the cover of an object such as a fallen log.
Apophallation has been reported only in some species of banana slug (Ariolimax) and one species of Deroceras. In the banana slugs, the penis sometimes becomes trapped inside the body of the partner. Apophallation allows the slugs to separate themselves by one or both of the slugs chewing off the other's or its own penis. Once the penis has been discarded, banana slugs are still able to mate using only the female parts of the reproductive system.
In a temperate climate, slugs usually live one year outdoors. In greenhouses, many adult slugs may live for more than one year.
Ecology
Slugs play an important role in the ecosystem by eating decaying plant material and fungi. Most carnivorous slugs on occasion also eat dead specimens of their own kind.
Feeding habits
Most species of slugs are generalists, feeding on a broad spectrum of organic materials, including leaves from living plants, lichens, mushrooms, and even carrion. Some slugs are predators and eat other slugs and snails, or earthworms.
Lehmannia feeding on a small fruit in Mexico City
Slugs can feed on a wide variety of vegetables and herbs, including flowers such as petunias, chrysanthemums, daisies, lobelia, lilies, dahlias, narcissus, gentians, primroses, tuberous begonias, hollyhocks, marigolds, and fruits such as strawberries. They also feed on carrots, peas, apples, and cabbage that are offered as a sole food source.
Slugs from different families are fungivores. It is the case in the Philomycidae (e. g. Philomycus carolinianus and Phylomicus flexuolaris) and Ariolimacidae (Ariolimax californianus), which respectively feed on slime molds (myxomycetes) and mushrooms (basidiomycetes).[16] Species of mushroom producing fungi used as food source by slugs include milk-caps, Lactarius spp., the oyster mushroom, Pleurotus ostreatus and the penny bun, Boletus edulis. Other species pertaining to different genera, such as Agaricus, Pleurocybella and Russula, are also eaten by slugs. Slime molds used as food source by slugs include Stemonitis axifera and Symphytocarpus flaccidus. Some slugs are selective towards certain parts or developmental stages of the fungi they eat, though this is very variable. Depending on the species and other factors, slugs eat only fungi at specific stages of development. Moreover, in other cases, whole mushrooms can be eaten, without any selection or bias towards ontogenetic stages.
Predators
Slugs are preyed upon by various vertebrates and invertebrates. The predation of slugs has been the subject of studies for at least a century. Because some species of slugs are considered agricultural pests, research investments have been made to discover and investigate potential predators in order to establish biological control strategies.
Vertebrates
Slugs are preyed upon by virtually every major vertebrate group. With many examples among reptiles, birds, mammals, amphibians and fish, vertebrates can occasionally feed on, or be specialised predators of, slugs. Fish that feed on slugs include the brown trout (Salmo trutta), which occasionally feeds on Arion circumscriptus, an arionid slug. Similarly, the shortjaw kokopu (Galaxias postvectis) includes slugs in its diet. Amphibians such as frogs and toads have long been regarded as important predators of slugs. Among them are species in the genus Bufo, Rhinella and Ceratophrys.
Reptiles that feed on slugs include mainly snakes and lizards. Some colubrid snakes are known predators of slugs. Coastal populations of the garter snake, Thamnophis elegans, have a specialised diet consisting of slugs, such as Ariolimax, while inland populations have a generalized diet. One of its congeners, the Northwestern garter snake (Thamnophis ordinoides), is not a specialized predator of slugs but occasionally feeds on them. The redbelly snake (Storeria occipitomaculata) and the brown snake (Storeria dekayi) feed mainly but not solely on slugs, while some species in the genus Dipsas (e.g. Dipsas neuwiedi) and the common slug eater snake (Duberria lutrix), are exclusively slug eaters. Several lizards include slugs in their diet. This is the case in the slowworm (Anguis fragilis), the bobtail lizard (Tiliqua rugosa), the she-oak skink (Cyclodomorphus casuarinae) and the common lizard (Zootoca vivipara).
Birds that prey upon slugs include common blackbirds (Turdus merula), starlings (Sturnus vulgaris), rooks (Corvus frugilegus), jackdaws (Corvus monedula), owls, vultures and ducks. Studies on slug predation also cite fieldfares (feeding on Deroceras reticulatum), redwings (feeding on Limax and Arion), thrushes (on Limax and Arion ater), red grouse (on Deroceras and Arion hortensis), game birds, wrynecks (on Limax flavus), rock doves and charadriiform birds as slug predators.
Mammals that eat slugs include foxes, badgers and hedgehogs.
Invertebrates
Beetles in the family Carabidae, such as Carabus violaceus and Pterostichus melanarius, are known to feed on slugs.Ants are a common predator of slugs; some ant species are deterred by the slug's mucus coating, while others such as driver ants will roll the slug in dirt to absorb its mucus.
Parasites and parasitoids
Slugs are parasitised by several organisms, including acari and a wide variety of nematodes. The slug mite, Riccardoella limacum, is known to parasitise several dozen species of molluscs, including many slugs, such as Deroceras reticulatum, Arianta arbustorum, Arion ater, Arion hortensis, Limax maximus, Tandonia budapestensis, Milax gagates, and Tandonia sowerbyi. R. limacum can often be seen swarming about their host's body, and live in its respiratory cavity.
Several species of nematodes are known to parasitise slugs. The nematode worms Agfa flexilis and Angiostoma limacis respectively live in the salivary glands and rectum of Limax maximus. Species of widely known medical importance pertaining to the genus Angiostrongylus are also parasites of slugs. Both Angiostrongylus costaricensis and Angiostrongylus cantonensis, a meningitis-causing nematode, have larval stages that can only live in molluscs, including slugs, such as Limax maximus.
Insects such as dipterans are known parasitoids of molluscs. To complete their development, many dipterans use slugs as hosts during their ontogeny. Some species of blow-flies (Calliphoridae) in the genus Melinda are known parasitoids of Arionidae, Limacidae and Philomycidae. Flies in the family Phoridae, specially those in the genus Megaselia, are parasitoids of Agriolimacidae, including many species of Deroceras. House flies in the family Muscidae, mainly those in the genus Sarcophaga, are facultative parasitoids of Arionidae.
Behavior
Slug contracts itself and retracts its tentacles when attacked
A brown and yellow spotted slug curled up into a tight ball so that its head is withdrawn completely, its mantle edge and tail are nearly touching, and none of its foot surface is exposed
The alarm response posture of the Kerry slug, which is found only in this species
When attacked, slugs can contract their body, making themselves harder and more compact and more still and round. By doing this, they become firmly attached to the substrate. This, combined with the slippery mucus they produce, makes slugs more difficult for predators to grasp. The unpleasant taste of the mucus is also a deterrent. Slugs can also incapacitate predators through the production of a highly sticky and elastic mucus which can trap predators in the secretion.
Some species present different response behaviors when attacked, such as the Kerry slug. In contrast to the general behavioral pattern, the Kerry slug retracts its head, lets go of the substrate, rolls up completely, and stays contracted in a ball-like shape. This is a unique feature among all the Arionidae, and among most other slugs. Some slugs can self-amputate (autotomy) a portion of their tail to help the slug escape from a predator. Some slug species hibernate underground during the winter in temperate climates, but in other species, the adults die in the autumn.
Intra- and inter-specific agonistic behavior is documented, but varies greatly among slug species. Slugs often resort to aggression, attacking both conspecifics and individuals from other species when competing for resources. This aggressiveness is also influenced by seasonality, because the availability of resources such as shelter and food may be compromised due to climatic conditions. Slugs are prone to attack during the summer, when the availability of resources is reduced. During winter, the aggressive responses are substituted by a gregarious behavior.
Human relevance
The great majority of slug species are harmless to humans and to their interests, but a small number of species are serious pests of agriculture and horticulture. They can destroy foliage faster than plants can grow, thus killing even fairly large plants. They also feed on fruits and vegetables prior to harvest, making holes in the crop, which can make individual items unsuitable to sell for aesthetic reasons, and can make the crop more vulnerable to rot and disease. Excessive buildup of slugs within some wastewater treatment plants with inadequate screening have been found to cause process issues resulting in increased energy and chemical use.
In a few rare cases, humans have developed Angiostrongylus cantonensis-induced meningitis from eating raw slugs. Live slugs that are accidentally eaten with improperly cleaned vegetables (such as lettuce), or improperly cooked slugs (for use in recipes requiring larger slugs such as banana slugs), can act as a vector for a parasitic infection in humans.
Prevention
As control measures, baits are commonly used in both agriculture and the garden. In recent years, iron phosphate baits have emerged and are preferred over the more toxic metaldehyde, especially because domestic or wild animals may be exposed to the bait. The environmentally safer iron phosphate has been shown to be at least as effective as baits. Methiocarb baits are no longer widely used. Parasitic nematodes (Phasmarhabditis hermaphrodita) are a commercially available biological control method that are effective against a wide range of common slug species. The nematodes are applied in water and actively seek out slugs in the soil and infect them, leading to the death of the slug. This control method is suitable for use in organic growing systems.
Other slug control methods are generally ineffective on a large scale, but can be somewhat useful in small gardens. These include beer traps [de], diatomaceous earth, crushed eggshells, coffee grounds, and copper. Salt kills slugs by causing water to leave the body owing to osmosis but this is not used for agricultural control as soil salinity is detrimental to crops. Conservation tillage worsens slug infestations. Hammond et al. 1999 find maize/corn and soybean in the US to be more severely affected under low till because this increases organic matter, thus providing food and shelter.
Charles Jencks's "The Century is Over, Evolutionary Tree of Twentieth-Century Architecture" with its attractor basins, scanned from Architectural Review, July 2000, p. 77.
See also this updated diagram from an Architectural Review article published March 2015.
Scanned from fourth edition of "The Language of Post-modern Architecture" (Academy Editions/Rizzoli, 1984).
I don't know the exact copyright of this illustration, but other Evolutionary Trees by Jencks have indicated "no copyright," so I'm marking this one public domain.
Rapid strata formation in soft sand (field evidence).
Photo of strata formation in soft sand on a beach, created by tidal action of the sea.
Formed in a single, high tidal event. Stunning evidence which displays multiple strata/layers.
Why this is so important ....
It has long been assumed, ever since the 17th century, that layers/strata observed in sedimentary rocks were built up gradually, layer upon layer, over many years. It certainly seemed logical at the time, from just looking at rocks, that lower layers would always be older than the layers above them, i.e. that lower layers were always laid down first followed, in time, by successive layers on top.
This was assumed to be true and became known as the superposition principle.
It was also assumed that a layer comprising a different material from a previous layer, represented a change in environmental conditions/factors.
These changes in composition of layers or strata were considered to represent different, geological eras on a global scale, spanning millions of years. This formed the basis for the Geologic Column, which is used to date rocks and also fossils. The evolutionary, 'fossil record' was based on the vast ages and assumed geological eras of the Geologic Column.
There was also circular reasoning applied with the assumed age of 'index' fossils (based on evolutionary beliefs & preconceptions) used to date strata in the Geologic Column. Dating strata from the assumed age of (index) fossils is known as Biostratigraphy.
We now know that, although these assumptions seemed logical, they are not supported by the evidence.
At the time, the mechanics of stratification were not properly known or studied.
An additional factor was that this assumed superposition and uniformitarian model became essential, with the wide acceptance of Darwinism, for the long ages required for progressive microbes-to-human evolution. There was no incentive to question or challenge the superposition, uniformitarian model, because the presumed, fossil 'record' had become dependant on it, and any change in the accepted model would present devastating implications for Darwinism.
This had the unfortunate effect of linking the study of geology so closely to Darwinism, that any study independent of Darwinian considerations was effectively stymied. This link of geology with Darwinian preconceptions is known as biostratigraphy.
Some other field evidence, in various situations, can be observed here: www.flickr.com/photos/101536517@N06/sets/72157635944904973/
and also in the links to stunning, experimental evidence, carried out by sedimentologists, given later.
_______________________________________________
GEOLOGIC PRINCIPLES (established by Nicholas Steno in the 17th Century):
What Nicolas Steno believed about strata formation is the basis of the principle of Superposition and the principle of Original Horizontality.
dictionary.sensagent.com/Law_of_superposition/en-en/
“Assuming that all rocks and minerals had once been fluid, Nicolas Steno reasoned that rock strata were formed when particles in a fluid such as water fell to the bottom. This process would leave horizontal layers. Thus Steno's principle of original horizontality states that rock layers form in the horizontal position, and any deviations from this horizontal position are due to the rocks being disturbed later.”)
BEDDING PLANES.
'Bedding plane' describes the surface in between each stratum which are formed during sediment deposition.
science.jrank.org/pages/6533/Strata.html
“Strata form during sediment deposition, that is, the laying down of sediment. Meanwhile, if a change in current speed or sediment grain size occurs or perhaps the sediment supply is cut off, a bedding plane forms. Bedding planes are surfaces that separate one stratum from another. Bedding planes can also form when the upper part of a sediment layer is eroded away before the next episode of deposition. Strata separated by a bedding plane may have different grain sizes, grain compositions, or colours. Sometimes these other traits are better indicators of stratification as bedding planes may be very subtle.”
______________________________________________
Several catastrophic events, flash floods, volcanic eruptions etc. have forced Darwinian, influenced geologists to admit to rapid stratification in some instances. However they claim it is a rare phenomenon, which they have known about for many years, and which does nothing to invalidate the Geologic Column, the fossil record, evolutionary timescale, or any of the old assumptions regarding strata formation, sedimentation and the superposition principle. They fail to face up to the fact that rapid stratification is not an extraordinary phenonemon, but rather the prevailing and normal mechanism of sedimentary deposition whenever and wherever there is moving, sediment-laden water. The experimental evidence demonstrates the mechanism and a mass of field evidence in normal (non-catastrophic) conditions shows it is a normal everyday occurrence.
It is clear from the experimental evidence that the usual process of stratification is - that strata are not formed by horizontal layers being laid on top of each other in succession, as was assumed. But by sediment being sorted in the flowing water and laid down diagonally in the direction of flow. See diagram:
www.flickr.com/photos/truth-in-science/39821536092/in/dat...
The field evidence (in the image) presented here - of rapid, simultaneous stratification refutes the Superposition Principle and the Principle of Lateral Continuity.
We now know, the Superposition Principle only applies on a rare occasion where sedimentary deposits are laid down in still water.
Superposition is required for the long evolutionary timescale, but the evidence shows it is not the general rule, as was once believed. Most sediment is laid down in moving water, where particle segregation is the general rule, resulting in the simultaneous deposition of strata/layers as shown in the photo.
See many other examples of rapid stratification (with geological features): www.flickr.com/photos/101536517@N06/sets/72157635944904973/
Rapid, simultaneous formation of layers/strata, through particle segregation in moving water, is so easily created it has even been described by sedimentologists (working on flume experiments) as a law ...
"Upon filling the tank with water and pouring in sediments, we immediately saw what was to become the rule: The sediments sorted themselves out in very clear layers. This became so common that by the end of two weeks, we jokingly referred to Andrew's law as "It's difficult not to make layers," and Clark's law as "It's easy to make layers." Later on, I proposed the "law" that liquefaction destroys layers, as much to my surprise as that was." Ian Juby, www.ianjuby.org/sedimentation/
The field example in the photo is the result of normal, everyday tidal action formed in a single incident,
Where the water current or movement is more turbulent, violent, or catastrophic, great depths (many metres) of stratified sediment can be laid down in a short time. Certainly not the many millions of years assumed by evolutionists.
The composition of strata formed in any deposition event. is related to whatever materials are in the sediment mix, not to any particular timescale. Whatever is in the mix will be automatically sorted into strata/layers. It could be sand, or other material added from mud slides, erosion of chalk deposits, coastal erosion, volcanic ash etc. Any organic material (potential fossils), alive or dead, engulfed by, or swept into, a turbulent sediment mix, will also be sorted and buried within the rapidly, forming layers.
See many other examples of rapid stratification with geological features: www.flickr.com/photos/101536517@N06/sets/72157635944904973/
Stratified, soft sand deposit. demonstrates the rapid, stratification principle.
Important, field evidence which supports the work of the eminent, sedimentologist Dr Guy Berthault MIAS - Member of the International Association of Sedimentologists.
(Dr Berthault's experiments (www.sedimentology.fr/)
And also the experimental work of Dr M.E. Clark (Professor Emeritus, U of Illinois @ Urbana), Andrew Rodenbeck and Dr. Henry Voss, (www.ianjuby.org/sedimentation/)
Location: Yaverland, Isle of Wight. photographed 04/06/2018, formed several months earlier and in the early stages of consolidation.
This field evidence demonstrates that multiple strata in sedimentary deposits do not need millions of years to form and can be formed rapidly. This natural example confirms the principle demonstrated by the sedimentation experiments carried out by Dr Guy Berthault and other sedimentologists. It calls into question the standard, multi-million year dating of sedimentary rocks, and the dating of fossils by depth of burial or position in the strata.
Mulltiple strata/layers are evident in this example.
Dr Berthault's experiments (www.sedimentology.fr/) and other experiments (www.ianjuby.org/sedimentation/) and field studies of floods and volcanic action show that, rather than being formed by gradual, slow deposition of sucessive layers superimposed upon previous layers, with the strata or layers representing a particular timescale, particle segregation in moving water or airborne particles can form strata or layers very quickly, frequently, in a single event.
And, most importantly, lower strata are not older than upper strata, they are the same age, having been created in the same sedimentary episode.
Such field studies confirm experiments which have shown that there is no longer any reason to conclude that strata/layers in sedimentary rocks relate to different geological eras and/or a multi-million year timescale. www.youtube.com/watch?v=5PVnBaqqQw8&feature=share&.... they also show that the relative position of fossils in rocks is not indicative of an order of evolutionary succession. Obviously, the uniformitarian principle, on which the geologic column is based, can no longer be considered valid. And the multi-million, year dating of sedimentary rocks and fossils needs to be reassessed. Rapid deposition of stratified sediments also explains the enigma of polystrate fossils, i.e. large fossils that intersect several strata. In some cases, tree trunk fossils are found which intersect the strata of sedimentary rock up to forty feet in depth. upload.wikimedia.org/wikipedia/commons/thumb/0/08/Lycopsi... They must have been buried in stratified sediment in a short time (certainly not millions, thousands, or even hundreds of years), or they would have rotted away. youtu.be/vnzHU9VsliQ
In fact, the vast majority of fossils are found in good, intact condition, which is testament to their rapid burial. You don't get good fossils from gradual burial, because they would be damaged or destroyed by decay, predation or erosion. The existence of so many fossils in sedimentary rock on a global scale is stunning evidence for the rapid depostion of sedimentary rock as the general rule. It is obvious that all rock containing good intact fossils was formed from sediment laid down in a very short time, not millions, or even thousands of years.
See set of photos of other examples of rapid stratification: www.flickr.com/photos/101536517@N06/sets/72157635944904973/
Carbon dating of coal should not be possible if it is millions of years old, yet significant amounts of Carbon 14 have been detected in coal and other fossil material, which indicates that it is less than 50,000 years old. www.ldolphin.org/sewell/c14dating.html
www.grisda.org/origins/51006.htm
Evolutionists confidently cite multi-million year ages for rocks and fossils, but what most people don't realise is that no one actually knows the age of sedimentary rocks or the fossils found within them. So how are evolutionists so sure of the ages they so confidently quote? The astonishing thing is they aren't. Sedimentary rocks cannot be dated by radiometric methods*, and fossils can only be dated to less than 50,000 years with Carbon 14 dating. The method evolutionists use is based entirely on assumptions. Unbelievably, fossils are dated by the assumed age of rocks, and rocks are dated by the assumed age of fossils, that's right ... it is known as circular reasoning.
* Regarding the radiometric dating of igneous rocks, which is claimed to be relevant to the dating of sedimentary rocks, in an occasional instance there is an igneous intrusion associated with a sedimentary deposit -
Prof. Aubouin says in his Précis de Géologie: "Each radioactive element disintegrates in a characteristic and constant manner, which depends neither on the physical state (no variation with pressure or temperature or any other external constraint) nor on the chemical state (identical for an oxide or a phosphate)."
"Rocks form when magma crystallizes. Crystallisation depends on pressure and temperature, from which radioactivity is independent. So, there is no relationship between radioactivity and crystallisation.
Consequently, radioactivity doesn't date the formation of rocks. Moreover, daughter elements contained in rocks result mainly from radioactivity in magma where gravity separates the heavier parent element, from the lighter daughter element. Thus radiometric dating has no chronological signification." Dr. Guy Berthault www.sciencevsevolution.org/Berthault.htm
"A team of Russian sedimentologists directed by Alexander Lalomov (Russian Academy of Sciences’ Institute of Ore Deposits) applied paleohydraulic analyses to geological formations in Russia. One example is the publication of a report in 2007 by the Lithology and Mineral Resources journal of the Russian Academy of Sciences. It concerns the Crimean Peninsular. It shows that the time of sedimentation of the sequence studied corresponds to a virtually instantaneous episode whilst according to stratigraphy it took several millions of years. Moreover, a recent report concerning the North-West Russian plateau in the St. Petersburg region shows that the time of sedimentation was much shorter than that attributed to it by the stratigraphic time-scale: 0.05% of the time."
www.sciencevsevolution.org/Berthault.htm
Rapid strata formation and rapid erosion at Mount St Helens.
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Visit the fossil museum:
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Just how good are peer reviews of scientific papers?
www.sciencemag.org/content/342/6154/60.full
www.examiner.com/article/want-to-publish-science-paper-ju...
The neo-Darwinian idea that the human genome consists entirely of an accumulation of billions of mutations is, quite obviously, completely bonkers. Nevertheless, it is compulsorily taught in schools and universities as 'science'.
Dashing Darlings of the Bird World…
"It's not going to happen while you're peering through your binoculars, but glossy starlings change color more than 10 times faster than their ancestors and even their modern relatives, according to researchers at The University of Akron and Columbia University. And these relatively rapid changes have led to new species of birds with color combinations previously unseen, according to the study funded in part by the National Science Foundation.
Source: www.sciencedaily.com
"Just like bar cruisers who don flashy clothes before a night out, birds use feathers to attract the opposite sex and intimidate the competition. The feathers aren't just there for flying."
The team of scientists used analysis of microscopic feather structures, spectral color analysis and evolutionary modeling to analyze patterns of evolution in Long Tailed, African or Meves's starlings, a diverse group of primarily brightly colored birds known for their metallic sheens. By comparison, the European starling -- the only starling found in the United States -- is a drab creature.
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Dr. E’s Golden Ratio Principle: The golden ratio exalts beauty because the number is a characteristic of the mathematically and physically most efficient manners of growth and distribution, on both evolutionary and purely physical levels. The golden ratio ensures that the proportions and structure of that which came before provide the proportions and structure of that which comes after, thusly providing symmetry over not only space but time, and exalting life’s foundational dynamic symmetry. Robust, ordered, symmetric growth is naturally associated with health and beauty, and thus we evolved to perceive the golden ratio harmonies as inherently beautiful, as we saw and felt their presence in all vital growth and life. In the salient features and proportions of humans and nature alike, from the distribution of our facial features and bones to the arrangements of petals, leaves, and sunflowers seeds. As ratios between Fibonacci Numbers offer the closest whole-number approximations to the golden ratio, and as seeds, cells, leaves, bones, and other physical entities appear in whole numbers, the Fibonacci Numbers oft appear in the arrangement of nature’s discrete elements as “growth’s numbers.” From the dawn of time, humanity sought to salute their gods in art and temples exalting the same proportion by which they and all their vital sustenance, as well as all the flowers and nature’s epic beauty, had been created—the golden ratio.
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Light Time Dimension Theory's dx4/dt=ic graces all the clothes, swimsuits, and lingerie!
Proof of Light Time Dimension Theory's principle of a fourth expanding dimension:
Proof of ltd’s principle:
1. The velocity of every object through
Spacetime is c.
2. The velocity of light through the
Three spatial dimensions is always c.
3. If light had any velocity through x4,
Light’s total velocity would not be c.
4. Ergo light remains stationary in x4.
5. Thus light tracks and traces the
Movement and character of x4.
6. As light is a spherically-symmetric,
Probabilistic wavefront expanding
At c, x4 expands at the rate of c in a
Spherically-symmetric manner,
Distributing nonlocality.
QED
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Fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group. As members of the phylum Chordata, fish share certain features with other vertebrates. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals—amphibians, reptiles, birds, and mammals. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Extant agnathans are the lampreys and the hagfishes. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. Sharks, skates, and rays are examples of cartilaginous fishes. The bony fishes are by far the largest class. Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone. Bony fishes also have an operculum that covers the gill slits.
The study of fishes, the science of ichthyology, is of broad importance. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.
Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. The zebra fish is used as a model in studies of gene expression.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Aquarium fishes provide a personal challenge to many aquarists, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing supports multimillion-dollar industries throughout the world.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 mm (0.4 inch) to more than 20 metres (60 feet) and in weight from about 1.5 grams (less than 0.06 ounce) to many thousands of kilograms. Some live in shallow thermal springs at temperatures slightly above 42 °C (100 °F), others in cold Arctic seas a few degrees below 0 °C (32 °F) or in cold deep waters more than 4,000 metres (13,100 feet) beneath the ocean surface. The structural and, especially, the physiological adaptations for life at such extremes are relatively poorly known and provide the scientifically curious with great incentive for study.
Almost all natural bodies of water bear fish life, the exceptions being very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. The present distribution of fishes is a result of the geological history and development of Earth as well as the ability of fishes to undergo evolutionary change and to adapt to the available habitats. Fishes may be seen to be distributed according to habitat and according to geographical area. Major habitat differences are marine and freshwater. For the most part, the fishes in a marine habitat differ from those in a freshwater habitat, even in adjacent areas, but some, such as the salmon, migrate from one to the other. The freshwater habitats may be seen to be of many kinds. Fishes found in mountain torrents, Arctic lakes, tropical lakes, temperate streams, and tropical rivers will all differ from each other, both in obvious gross structure and in physiological attributes. Even in closely adjacent habitats where, for example, a tropical mountain torrent enters a lowland stream, the fish fauna will differ. The marine habitats can be divided into deep ocean floors (benthic), mid-water oceanic (bathypelagic), surface oceanic (pelagic), rocky coast, sandy coast, muddy shores, bays, estuaries, and others. Also, for example, rocky coastal shores in tropical and temperate regions will have different fish faunas, even when such habitats occur along the same coastline.
Although much is known about the present geographical distribution of fishes, far less is known about how that distribution came about. Many parts of the fish fauna of the fresh waters of North America and Eurasia are related and undoubtedly have a common origin. The faunas of Africa and South America are related, extremely old, and probably an expression of the drifting apart of the two continents. The fauna of southern Asia is related to that of Central Asia, and some of it appears to have entered Africa. The extremely large shore-fish faunas of the Indian and tropical Pacific oceans comprise a related complex, but the tropical shore fauna of the Atlantic, although containing Indo-Pacific components, is relatively limited and probably younger. The Arctic and Antarctic marine faunas are quite different from each other. The shore fauna of the North Pacific is quite distinct, and that of the North Atlantic more limited and probably younger. Pelagic oceanic fishes, especially those in deep waters, are similar the world over, showing little geographical isolation in terms of family groups. The deep oceanic habitat is very much the same throughout the world, but species differences do exist, showing geographical areas determined by oceanic currents and water masses.
All aspects of the life of a fish are closely correlated with adaptation to the total environment, physical, chemical, and biological. In studies, all the interdependent aspects of fish, such as behaviour, locomotion, reproduction, and physical and physiological characteristics, must be taken into account.
Correlated with their adaptation to an extremely wide variety of habitats is the extremely wide variety of life cycles that fishes display. The great majority hatch from relatively small eggs a few days to several weeks or more after the eggs are scattered in the water. Newly hatched young are still partially undeveloped and are called larvae until body structures such as fins, skeleton, and some organs are fully formed. Larval life is often very short, usually less than a few weeks, but it can be very long, some lampreys continuing as larvae for at least five years. Young and larval fishes, before reaching sexual maturity, must grow considerably, and their small size and other factors often dictate that they live in a habitat different than that of the adults. For example, most tropical marine shore fishes have pelagic larvae. Larval food also is different, and larval fishes often live in shallow waters, where they may be less exposed to predators.
After a fish reaches adult size, the length of its life is subject to many factors, such as innate rates of aging, predation pressure, and the nature of the local climate. The longevity of a species in the protected environment of an aquarium may have nothing to do with how long members of that species live in the wild. Many small fishes live only one to three years at the most. In some species, however, individuals may live as long as 10 or 20 or even 100 years.
Fish behaviour is a complicated and varied subject. As in almost all animals with a central nervous system, the nature of a response of an individual fish to stimuli from its environment depends upon the inherited characteristics of its nervous system, on what it has learned from past experience, and on the nature of the stimuli. Compared with the variety of human responses, however, that of a fish is stereotyped, not subject to much modification by “thought” or learning, and investigators must guard against anthropomorphic interpretations of fish behaviour.
Fishes perceive the world around them by the usual senses of sight, smell, hearing, touch, and taste and by special lateral line water-current detectors. In the few fishes that generate electric fields, a process that might best be called electrolocation aids in perception. One or another of these senses often is emphasized at the expense of others, depending upon the fish’s other adaptations. In fishes with large eyes, the sense of smell may be reduced; others, with small eyes, hunt and feed primarily by smell (such as some eels).
Specialized behaviour is primarily concerned with the three most important activities in the fish’s life: feeding, reproduction, and escape from enemies. Schooling behaviour of sardines on the high seas, for instance, is largely a protective device to avoid enemies, but it is also associated with and modified by their breeding and feeding requirements. Predatory fishes are often solitary, lying in wait to dart suddenly after their prey, a kind of locomotion impossible for beaked parrot fishes, which feed on coral, swimming in small groups from one coral head to the next. In addition, some predatory fishes that inhabit pelagic environments, such as tunas, often school.
Sleep in fishes, all of which lack true eyelids, consists of a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most can dart away. A few kinds of fishes lie on the bottom to sleep. Most catfishes, some loaches, and some eels and electric fishes are strictly nocturnal, being active and hunting for food during the night and retiring during the day to holes, thick vegetation, or other protective parts of the environment.
Communication between members of a species or between members of two or more species often is extremely important, especially in breeding behaviour (see below Reproduction). The mode of communication may be visual, as between the small so-called cleaner fish and a large fish of a very different species. The larger fish often allows the cleaner to enter its mouth to remove gill parasites. The cleaner is recognized by its distinctive colour and actions and therefore is not eaten, even if the larger fish is normally a predator. Communication is often chemical, signals being sent by specific chemicals called pheromones.
Many fishes have a streamlined body and swim freely in open water. Fish locomotion is closely correlated with habitat and ecological niche (the general position of the animal to its environment).
Many fishes in both marine and fresh waters swim at the surface and have mouths adapted to feed best (and sometimes only) at the surface. Often such fishes are long and slender, able to dart at surface insects or at other surface fishes and in turn to dart away from predators; needlefishes, halfbeaks, and topminnows (such as killifish and mosquito fish) are good examples. Oceanic flying fishes escape their predators by gathering speed above the water surface, with the lower lobe of the tail providing thrust in the water. They then glide hundreds of yards on enlarged, winglike pectoral and pelvic fins. South American freshwater flying fishes escape their enemies by jumping and propelling their strongly keeled bodies out of the water.
So-called mid-water swimmers, the most common type of fish, are of many kinds and live in many habitats. The powerful fusiform tunas and the trouts, for example, are adapted for strong, fast swimming, the tunas to capture prey speedily in the open ocean and the trouts to cope with the swift currents of streams and rivers. The trout body form is well adapted to many habitats. Fishes that live in relatively quiet waters such as bays or lake shores or slow rivers usually are not strong, fast swimmers but are capable of short, quick bursts of speed to escape a predator. Many of these fishes have their sides flattened, examples being the sunfish and the freshwater angelfish of aquarists. Fish associated with the bottom or substrate usually are slow swimmers. Open-water plankton-feeding fishes almost always remain fusiform and are capable of rapid, strong movement (for example, sardines and herrings of the open ocean and also many small minnows of streams and lakes).
Bottom-living fishes are of many kinds and have undergone many types of modification of their body shape and swimming habits. Rays, which evolved from strong-swimming mid-water sharks, usually stay close to the bottom and move by undulating their large pectoral fins. Flounders live in a similar habitat and move over the bottom by undulating the entire body. Many bottom fishes dart from place to place, resting on the bottom between movements, a motion common in gobies. One goby relative, the mudskipper, has taken to living at the edge of pools along the shore of muddy mangrove swamps. It escapes its enemies by flipping rapidly over the mud, out of the water. Some catfishes, synbranchid eels, the so-called climbing perch, and a few other fishes venture out over damp ground to find more promising waters than those that they left. They move by wriggling their bodies, sometimes using strong pectoral fins; most have accessory air-breathing organs. Many bottom-dwelling fishes live in mud holes or rocky crevices. Marine eels and gobies commonly are found in such habitats and for the most part venture far beyond their cavelike homes. Some bottom dwellers, such as the clingfishes (Gobiesocidae), have developed powerful adhesive disks that enable them to remain in place on the substrate in areas such as rocky coasts, where the action of the waves is great.
The methods of reproduction in fishes are varied, but most fishes lay a large number of small eggs, fertilized and scattered outside of the body. The eggs of pelagic fishes usually remain suspended in the open water. Many shore and freshwater fishes lay eggs on the bottom or among plants. Some have adhesive eggs. The mortality of the young and especially of the eggs is very high, and often only a few individuals grow to maturity out of hundreds, thousands, and in some cases millions of eggs laid.
Males produce sperm, usually as a milky white substance called milt, in two (sometimes one) testes within the body cavity. In bony fishes a sperm duct leads from each testis to a urogenital opening behind the vent or anus. In sharks and rays and in cyclostomes the duct leads to a cloaca. Sometimes the pelvic fins are modified to help transmit the milt to the eggs at the female’s vent or on the substrate where the female has placed them. Sometimes accessory organs are used to fertilize females internally—for example, the claspers of many sharks and rays.
In the females the eggs are formed in two ovaries (sometimes only one) and pass through the ovaries to the urogenital opening and to the outside. In some fishes the eggs are fertilized internally but are shed before development takes place. Members of about a dozen families each of bony fishes (teleosts) and sharks bear live young. Many skates and rays also bear live young. In some bony fishes the eggs simply develop within the female, the young emerging when the eggs hatch (ovoviviparous). Others develop within the ovary and are nourished by ovarian tissues after hatching (viviparous). There are also other methods utilized by fishes to nourish young within the female. In all live-bearers the young are born at a relatively large size and are few in number. In one family of primarily marine fishes, the surfperches from the Pacific coast of North America, Japan, and Korea, the males of at least one species are born sexually mature, although they are not fully grown.
Some fishes are hermaphroditic—an individual producing both sperm and eggs, usually at different stages of its life. Self-fertilization, however, is probably rare.
Successful reproduction and, in many cases, defense of the eggs and the young are assured by rather stereotypical but often elaborate courtship and parental behaviour, either by the male or the female or both. Some fishes prepare nests by hollowing out depressions in the sand bottom (cichlids, for example), build nests with plant materials and sticky threads excreted by the kidneys (sticklebacks), or blow a cluster of mucus-covered bubbles at the water surface (gouramis). The eggs are laid in these structures. Some varieties of cichlids and catfishes incubate eggs in their mouths.
Some fishes, such as salmon, undergo long migrations from the ocean and up large rivers to spawn in the gravel beds where they themselves hatched (anadromous fishes). Some, such as the freshwater eels (family Anguillidae), live and grow to maturity in fresh water and migrate to the sea to spawn (catadromous fishes). Other fishes undertake shorter migrations from lakes into streams, within the ocean, or enter spawning habitats that they do not ordinarily occupy in other ways.
The basic structure and function of the fish body are similar to those of all other vertebrates. The usual four types of tissues are present: surface or epithelial, connective (bone, cartilage, and fibrous tissues, as well as their derivative, blood), nerve, and muscle tissues. In addition, the fish’s organs and organ systems parallel those of other vertebrates.
The typical fish body is streamlined and spindle-shaped, with an anterior head, a gill apparatus, and a heart, the latter lying in the midline just below the gill chamber. The body cavity, containing the vital organs, is situated behind the head in the lower anterior part of the body. The anus usually marks the posterior termination of the body cavity and most often occurs just in front of the base of the anal fin. The spinal cord and vertebral column continue from the posterior part of the head to the base of the tail fin, passing dorsal to the body cavity and through the caudal (tail) region behind the body cavity. Most of the body is of muscular tissue, a high proportion of which is necessitated by swimming. In the course of evolution this basic body plan has been modified repeatedly into the many varieties of fish shapes that exist today.
The skeleton forms an integral part of the fish’s locomotion system, as well as serving to protect vital parts. The internal skeleton consists of the skull bones (except for the roofing bones of the head, which are really part of the external skeleton), the vertebral column, and the fin supports (fin rays). The fin supports are derived from the external skeleton but will be treated here because of their close functional relationship to the internal skeleton. The internal skeleton of cyclostomes, sharks, and rays is of cartilage; that of many fossil groups and some primitive living fishes is mostly of cartilage but may include some bone. In place of the vertebral column, the earliest vertebrates had a fully developed notochord, a flexible stiff rod of viscous cells surrounded by a strong fibrous sheath. During the evolution of modern fishes the rod was replaced in part by cartilage and then by ossified cartilage. Sharks and rays retain a cartilaginous vertebral column; bony fishes have spool-shaped vertebrae that in the more primitive living forms only partially replace the notochord. The skull, including the gill arches and jaws of bony fishes, is fully, or at least partially, ossified. That of sharks and rays remains cartilaginous, at times partially replaced by calcium deposits but never by true bone.
The supportive elements of the fins (basal or radial bones or both) have changed greatly during fish evolution. Some of these changes are described in the section below (Evolution and paleontology). Most fishes possess a single dorsal fin on the midline of the back. Many have two and a few have three dorsal fins. The other fins are the single tail and anal fins and paired pelvic and pectoral fins. A small fin, the adipose fin, with hairlike fin rays, occurs in many of the relatively primitive teleosts (such as trout) on the back near the base of the caudal fin.
The skin of a fish must serve many functions. It aids in maintaining the osmotic balance, provides physical protection for the body, is the site of coloration, contains sensory receptors, and, in some fishes, functions in respiration. Mucous glands, which aid in maintaining the water balance and offer protection from bacteria, are extremely numerous in fish skin, especially in cyclostomes and teleosts. Since mucous glands are present in the modern lampreys, it is reasonable to assume that they were present in primitive fishes, such as the ancient Silurian and Devonian agnathans. Protection from abrasion and predation is another function of the fish skin, and dermal (skin) bone arose early in fish evolution in response to this need. It is thought that bone first evolved in skin and only later invaded the cartilaginous areas of the fish’s body, to provide additional support and protection. There is some argument as to which came first, cartilage or bone, and fossil evidence does not settle the question. In any event, dermal bone has played an important part in fish evolution and has different characteristics in different groups of fishes. Several groups are characterized at least in part by the kind of bony scales they possess.
Scales have played an important part in the evolution of fishes. Primitive fishes usually had thick bony plates or thick scales in several layers of bone, enamel, and related substances. Modern teleost fishes have scales of bone, which, while still protective, allow much more freedom of motion in the body. A few modern teleosts (some catfishes, sticklebacks, and others) have secondarily acquired bony plates in the skin. Modern and early sharks possessed placoid scales, a relatively primitive type of scale with a toothlike structure, consisting of an outside layer of enamel-like substance (vitrodentine), an inner layer of dentine, and a pulp cavity containing nerves and blood vessels. Primitive bony fishes had thick scales of either the ganoid or the cosmoid type. Cosmoid scales have a hard, enamel-like outer layer, an inner layer of cosmine (a form of dentine), and then a layer of vascular bone (isopedine). In ganoid scales the hard outer layer is different chemically and is called ganoin. Under this is a cosminelike layer and then a vascular bony layer. The thin, translucent bony scales of modern fishes, called cycloid and ctenoid (the latter distinguished by serrations at the edges), lack enameloid and dentine layers.
Skin has several other functions in fishes. It is well supplied with nerve endings and presumably receives tactile, thermal, and pain stimuli. Skin is also well supplied with blood vessels. Some fishes breathe in part through the skin, by the exchange of oxygen and carbon dioxide between the surrounding water and numerous small blood vessels near the skin surface.
Skin serves as protection through the control of coloration. Fishes exhibit an almost limitless range of colours. The colours often blend closely with the surroundings, effectively hiding the animal. Many fishes use bright colours for territorial advertisement or as recognition marks for other members of their own species, or sometimes for members of other species. Many fishes can change their colour to a greater or lesser degree, by movement of pigment within the pigment cells (chromatophores). Black pigment cells (melanophores), of almost universal occurrence in fishes, are often juxtaposed with other pigment cells. When placed beneath iridocytes or leucophores (bearing the silvery or white pigment guanine), melanophores produce structural colours of blue and green. These colours are often extremely intense, because they are formed by refraction of light through the needlelike crystals of guanine. The blue and green refracted colours are often relatively pure, lacking the red and yellow rays, which have been absorbed by the black pigment (melanin) of the melanophores. Yellow, orange, and red colours are produced by erythrophores, cells containing the appropriate carotenoid pigments. Other colours are produced by combinations of melanophores, erythrophores, and iridocytes.
The major portion of the body of most fishes consists of muscles. Most of the mass is trunk musculature, the fin muscles usually being relatively small. The caudal fin is usually the most powerful fin, being moved by the trunk musculature. The body musculature is usually arranged in rows of chevron-shaped segments on each side. Contractions of these segments, each attached to adjacent vertebrae and vertebral processes, bends the body on the vertebral joint, producing successive undulations of the body, passing from the head to the tail, and producing driving strokes of the tail. It is the latter that provides the strong forward movement for most fishes.
The digestive system, in a functional sense, starts at the mouth, with the teeth used to capture prey or collect plant foods. Mouth shape and tooth structure vary greatly in fishes, depending on the kind of food normally eaten. Most fishes are predacious, feeding on small invertebrates or other fishes and have simple conical teeth on the jaws, on at least some of the bones of the roof of the mouth, and on special gill arch structures just in front of the esophagus. The latter are throat teeth. Most predacious fishes swallow their prey whole, and the teeth are used for grasping and holding prey, for orienting prey to be swallowed (head first) and for working the prey toward the esophagus. There are a variety of tooth types in fishes. Some fishes, such as sharks and piranhas, have cutting teeth for biting chunks out of their victims. A shark’s tooth, although superficially like that of a piranha, appears in many respects to be a modified scale, while that of the piranha is like that of other bony fishes, consisting of dentine and enamel. Parrot fishes have beaklike mouths with short incisor-like teeth for breaking off coral and have heavy pavementlike throat teeth for crushing the coral. Some catfishes have small brushlike teeth, arranged in rows on the jaws, for scraping plant and animal growth from rocks. Many fishes (such as the Cyprinidae or minnows) have no jaw teeth at all but have very strong throat teeth.
Some fishes gather planktonic food by straining it from their gill cavities with numerous elongate stiff rods (gill rakers) anchored by one end to the gill bars. The food collected on these rods is passed to the throat, where it is swallowed. Most fishes have only short gill rakers that help keep food particles from escaping out the mouth cavity into the gill chamber.
Once reaching the throat, food enters a short, often greatly distensible esophagus, a simple tube with a muscular wall leading into a stomach. The stomach varies greatly in fishes, depending upon the diet. In most predacious fishes it is a simple straight or curved tube or pouch with a muscular wall and a glandular lining. Food is largely digested there and leaves the stomach in liquid form.
Between the stomach and the intestine, ducts enter the digestive tube from the liver and pancreas. The liver is a large, clearly defined organ. The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine. The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca (blind sacs) occur in some fishes at this junction and have a digestive or absorptive function or both.
The intestine itself is quite variable in length, depending upon the fish’s diet. It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency, and a spiral valve is one method of increasing its absorption surface.
Sharks, rays, chimaeras, lungfishes, surviving chondrosteans, holosteans, and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi (fingerlike projections) somewhat like those in humans. Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system.
Oxygen and carbon dioxide dissolve in water, and most fishes exchange dissolved oxygen and carbon dioxide in water by means of the gills. The gills lie behind and to the side of the mouth cavity and consist of fleshy filaments supported by the gill arches and filled with blood vessels, which give gills a bright red colour. Water taken in continuously through the mouth passes backward between the gill bars and over the gill filaments, where the exchange of gases takes place. The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.
Most modern fishes have a hydrostatic (ballast) organ, called the swim bladder, that lies in the body cavity just below the kidney and above the stomach and intestine. It originated as a diverticulum of the digestive canal. In advanced teleosts, especially the acanthopterygians, the bladder has lost its connection with the digestive tract, a condition called physoclistic. The connection has been retained (physostomous) by many relatively primitive teleosts. In several unrelated lines of fishes, the bladder has become specialized as a lung or, at least, as a highly vascularized accessory breathing organ. Some fishes with such accessory organs are obligate air breathers and will drown if denied access to the surface, even in well-oxygenated water. Fishes with a hydrostatic form of swim bladder can control their depth by regulating the amount of gas in the bladder. The gas, mostly oxygen, is secreted into the bladder by special glands, rendering the fish more buoyant; the gas is absorbed into the bloodstream by another special organ, reducing the overall buoyancy and allowing the fish to sink. Some deep-sea fishes may have oils, rather than gas, in the bladder. Other deep-sea and some bottom-living forms have much-reduced swim bladders or have lost the organ entirely.
The swim bladder of fishes follows the same developmental pattern as the lungs of land vertebrates. There is no doubt that the two structures have the same historical origin in primitive fishes. More or less intermediate forms still survive among the more primitive types of fishes, such as the lungfishes Lepidosiren and Protopterus.
The circulatory, or blood vascular, system consists of the heart, the arteries, the capillaries, and the veins. It is in the capillaries that the interchange of oxygen, carbon dioxide, nutrients, and other substances such as hormones and waste products takes place. The capillaries lead to the veins, which return the venous blood with its waste products to the heart, kidneys, and gills. There are two kinds of capillary beds: those in the gills and those in the rest of the body. The heart, a folded continuous muscular tube with three or four saclike enlargements, undergoes rhythmic contractions and receives venous blood in a sinus venosus. It passes the blood to an auricle and then into a thick muscular pump, the ventricle. From the ventricle the blood goes to a bulbous structure at the base of a ventral aorta just below the gills. The blood passes to the afferent (receiving) arteries of the gill arches and then to the gill capillaries. There waste gases are given off to the environment, and oxygen is absorbed. The oxygenated blood enters efferent (exuant) arteries of the gill arches and then flows into the dorsal aorta. From there blood is distributed to the tissues and organs of the body. One-way valves prevent backflow. The circulation of fishes thus differs from that of the reptiles, birds, and mammals in that oxygenated blood is not returned to the heart prior to distribution to the other parts of the body.
The primary excretory organ in fishes, as in other vertebrates, is the kidney. In fishes some excretion also takes place in the digestive tract, skin, and especially the gills (where ammonia is given off). Compared with land vertebrates, fishes have a special problem in maintaining their internal environment at a constant concentration of water and dissolved substances, such as salts. Proper balance of the internal environment (homeostasis) of a fish is in a great part maintained by the excretory system, especially the kidney.
The kidney, gills, and skin play an important role in maintaining a fish’s internal environment and checking the effects of osmosis. Marine fishes live in an environment in which the water around them has a greater concentration of salts than they can have inside their body and still maintain life. Freshwater fishes, on the other hand, live in water with a much lower concentration of salts than they require inside their bodies. Osmosis tends to promote the loss of water from the body of a marine fish and absorption of water by that of a freshwater fish. Mucus in the skin tends to slow the process but is not a sufficient barrier to prevent the movement of fluids through the permeable skin. When solutions on two sides of a permeable membrane have different concentrations of dissolved substances, water will pass through the membrane into the more concentrated solution, while the dissolved chemicals move into the area of lower concentration (diffusion).
The kidney of freshwater fishes is often larger in relation to body weight than that of marine fishes. In both groups the kidney excretes wastes from the body, but the kidney of freshwater fishes also excretes large amounts of water, counteracting the water absorbed through the skin. Freshwater fishes tend to lose salt to the environment and must replace it. They get some salt from their food, but the gills and skin inside the mouth actively absorb salt from water passed through the mouth. This absorption is performed by special cells capable of moving salts against the diffusion gradient. Freshwater fishes drink very little water and take in little water with their food.
Marine fishes must conserve water, and therefore their kidneys excrete little water. To maintain their water balance, marine fishes drink large quantities of seawater, retaining most of the water and excreting the salt. Most nitrogenous waste in marine fishes appears to be secreted by the gills as ammonia. Marine fishes can excrete salt by clusters of special cells (chloride cells) in the gills.
There are several teleosts—for example, the salmon—that travel between fresh water and seawater and must adjust to the reversal of osmotic gradients. They adjust their physiological processes by spending time (often surprisingly little time) in the intermediate brackish environment.
Marine hagfishes, sharks, and rays have osmotic concentrations in their blood about equal to that of seawater and so do not have to drink water nor perform much physiological work to maintain their osmotic balance. In sharks and rays the osmotic concentration is kept high by retention of urea in the blood. Freshwater sharks have a lowered concentration of urea in the blood.
Endocrine glands secrete their products into the bloodstream and body tissues and, along with the central nervous system, control and regulate many kinds of body functions. Cyclostomes have a well-developed endocrine system, and presumably it was well developed in the early Agnatha, ancestral to modern fishes. Although the endocrine system in fishes is similar to that of higher vertebrates, there are numerous differences in detail. The pituitary, the thyroid, the suprarenals, the adrenals, the pancreatic islets, the sex glands (ovaries and testes), the inner wall of the intestine, and the bodies of the ultimobranchial gland make up the endocrine system in fishes. There are some others whose function is not well understood. These organs regulate sexual activity and reproduction, growth, osmotic pressure, general metabolic activities such as the storage of fat and the utilization of foodstuffs, blood pressure, and certain aspects of skin colour. Many of these activities are also controlled in part by the central nervous system, which works with the endocrine system in maintaining the life of a fish. Some parts of the endocrine system are developmentally, and undoubtedly evolutionarily, derived from the nervous system.
As in all vertebrates, the nervous system of fishes is the primary mechanism coordinating body activities, as well as integrating these activities in the appropriate manner with stimuli from the environment. The central nervous system, consisting of the brain and spinal cord, is the primary integrating mechanism. The peripheral nervous system, consisting of nerves that connect the brain and spinal cord to various body organs, carries sensory information from special receptor organs such as the eyes, internal ears, nares (sense of smell), taste glands, and others to the integrating centres of the brain and spinal cord. The peripheral nervous system also carries information via different nerve cells from the integrating centres of the brain and spinal cord. This coded information is carried to the various organs and body systems, such as the skeletal muscular system, for appropriate action in response to the original external or internal stimulus. Another branch of the nervous system, the autonomic nervous system, helps to coordinate the activities of many glands and organs and is itself closely connected to the integrating centres of the brain.
The brain of the fish is divided into several anatomical and functional parts, all closely interconnected but each serving as the primary centre of integrating particular kinds of responses and activities. Several of these centres or parts are primarily associated with one type of sensory perception, such as sight, hearing, or smell (olfaction).
The sense of smell is important in almost all fishes. Certain eels with tiny eyes depend mostly on smell for location of food. The olfactory, or nasal, organ of fishes is located on the dorsal surface of the snout. The lining of the nasal organ has special sensory cells that perceive chemicals dissolved in the water, such as substances from food material, and send sensory information to the brain by way of the first cranial nerve. Odour also serves as an alarm system. Many fishes, especially various species of freshwater minnows, react with alarm to a chemical released from the skin of an injured member of their own species.
Many fishes have a well-developed sense of taste, and tiny pitlike taste buds or organs are located not only within their mouth cavities but also over their heads and parts of their body. Catfishes, which often have poor vision, have barbels (“whiskers”) that serve as supplementary taste organs, those around the mouth being actively used to search out food on the bottom. Some species of naturally blind cave fishes are especially well supplied with taste buds, which often cover most of their body surface.
Sight is extremely important in most fishes. The eye of a fish is basically like that of all other vertebrates, but the eyes of fishes are extremely varied in structure and adaptation. In general, fishes living in dark and dim water habitats have large eyes, unless they have specialized in some compensatory way so that another sense (such as smell) is dominant, in which case the eyes will often be reduced. Fishes living in brightly lighted shallow waters often will have relatively small but efficient eyes. Cyclostomes have somewhat less elaborate eyes than other fishes, with skin stretched over the eyeball perhaps making their vision somewhat less effective. Most fishes have a spherical lens and accommodate their vision to far or near subjects by moving the lens within the eyeball. A few sharks accommodate by changing the shape of the lens, as in land vertebrates. Those fishes that are heavily dependent upon the eyes have especially strong muscles for accommodation. Most fishes see well, despite the restrictions imposed by frequent turbidity of the water and by light refraction.
Fossil evidence suggests that colour vision evolved in fishes more than 300 million years ago, but not all living fishes have retained this ability. Experimental evidence indicates that many shallow-water fishes, if not all, have colour vision and see some colours especially well, but some bottom-dwelling shore fishes live in areas where the water is sufficiently deep to filter out most if not all colours, and these fishes apparently never see colours. When tested in shallow water, they apparently are unable to respond to colour differences.
Sound perception and balance are intimately associated senses in a fish. The organs of hearing are entirely internal, located within the skull, on each side of the brain and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body, to be transmitted to the hearing organs. Fishes readily respond to sound; for example, a trout conditioned to escape by the approach of fishermen will take flight upon perceiving footsteps on a stream bank even if it cannot see a fisherman. Compared with humans, however, the range of sound frequencies heard by fishes is greatly restricted. Many fishes communicate with each other by producing sounds in their swim bladders, in their throats by rasping their teeth, and in other ways.
A fish or other vertebrate seldom has to rely on a single type of sensory information to determine the nature of the environment around it. A catfish uses taste and touch when examining a food object with its oral barbels. Like most other animals, fishes have many touch receptors over their body surface. Pain and temperature receptors also are present in fishes and presumably produce the same kind of information to a fish as to humans. Fishes react in a negative fashion to stimuli that would be painful to human beings, suggesting that they feel a sensation of pain.
An important sensory system in fishes that is absent in other vertebrates (except some amphibians) is the lateral line system. This consists of a series of heavily innervated small canals located in the skin and bone around the eyes, along the lower jaw, over the head, and down the mid-side of the body, where it is associated with the scales. Intermittently along these canals are located tiny sensory organs (pit organs) that apparently detect changes in pressure. The system allows a fish to sense changes in water currents and pressure, thereby helping the fish to orient itself to the various changes that occur in the physical environment.
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Proof of ltd’s principle:
1. The velocity of every object through
Spacetime is c.
2. The velocity of light through the
Three spatial dimensions is always c.
3. If light had any velocity through x4,
Light’s total velocity would not be c.
4. Ergo light remains stationary in x4.
5. Thus light tracks and traces the
Movement and character of x4.
6. As light is a spherically-symmetric,
Probabilistic wavefront expanding
At c, x4 expands at the rate of c in a
Spherically-symmetric manner,
Distributing nonlocality.
QED
Alright, this tank has reached it's evolutionary high point, it's now an apex tank. Like an apex predator. Kind of. Not really.
But yea, it's finally been fully modernized. I like it very much. I'll be using them for the Roman Empire, replacing the much uglier Feroun, and they will also be shipped off to Tomland. He ordered this, anyway.
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
Some background:
When Marcel Dassault started work on jet-powered fighters after WWII, the development evolved in gradual steps instead of quantum leaps, leading to a long line of aircraft. The Mystère IV was an evolutionary development of the Mystère II aircraft. Although bearing an external resemblance to the earlier aircraft, the Mystère IV was in fact a new design with aerodynamic improvements for supersonic flight. The prototype first flew on 28 September 1952, and the aircraft entered service in April 1953. The first 50 Mystere IVA production aircraft were powered by British Rolls-Royce Tay turbojets, while the remainder had the French-built Hispano-Suiza Verdon 350 version of that engine.
France was the main operator of the Mystère IV. In April 1953 the United States government and the United States Air Force placed an order for 223 aircraft to be operated by the French, and at the peak usage the Armée de l‘air operated 6 squadrons. Most of the aircraft were purchased under a United States Offshore Procurement contract and many were returned to US custody after they were retired. The Mystère IVs were used in the 1956 Suez Crisis and continued to remain in French service into the 1980s, even though they were quickly relegated into second line duties as more capable types like the Super Mystère SM2B or the Mirage III entered service.
Other international operators included Israel (using about sixty Mystère IVs in large-scale combat during the 1967 Six Day War), India (104 aircraft procured in 1957 and extensively used in the Indo-Pakistani War of 1965) and Ecuador.
The Fuerza Aérea Ecuatoriana (FAE, Ecuadorian Air Force) was officially created on October 27, 1920. However, like in many other countries, military flying activity already started before the formal date of birth of the Air Force. By 1939 the Ecuadorian Air Force was still limited to about 30 aircraft, though, and a staff of about 60, including 10 officers. Military aviation did not start in earnest until the early forties when an Ecuadorian mission to the United States resulted in the delivery of an assortment of aircraft for the Aviation school at Salinas: three Ryan PT-22 Recruits, six Curtiss-Wright CW-22 Falcons, six Fairchild PT-19A Cornells and three North American AT-6A Harvards arrived in March 1942, considerably boosting the capacity of the Escuela de Aviación at Salinas.
The 1950s and 1960s saw a further necessary buildup of the air force, gaining more units and aircraft, while efforts were made in enhancing the facilities at various airbases. In May 1961 the "First Air Zone" with its subordinate unit Ala de Transportes No.11 was founded. The "Second Air Zone" controlled the units in the southern half of Ecuador, Ala de Combate No.21 at Taura, Ala de Rescate No.22 at Guayaquil and Ala de Combate No.23 at Manta as well as the Escuela Superior Militar de Aviación "Cosme Rennella B." (ESMA) at Salinas.
It was at this time that the FAE was looking for a capable (yet affordable) jet fighter that would replace the vintage F-47 “Thunderbolt” piston engine fighters of American origin that had been operated since 1947 as well as the ageing fleet of Gloster Meteor jet fighters. After consulting various options, including the British Hawker Hunter and the American F-86 Sabre, Ecuador settled upon the French Mystère IV. A total of 32 aircraft were ordered in 1958 and delivered until early 1963 in two tranches, subsequently outfitting two combat squadrons.
The Ecuadorian aircraft resembled the early French Mystère IV standard and were powered by the British Rolls-Royce Tay 250. However, they differed in small details and incorporated some updates, leading to the individual designation Mystère IVE (for Ecuador). This included a modified instrumentation and a British Martin Baker ejection seat in the cockpit. On the outside, a fairing for a brake parachute at the fin’s base was the most obvious change, and there were small oval boundary layer fences on the wings’ leading edges that improved the aircraft’s handling. The front landing gear was slightly different, too, now outfitted with a mudguard.
To improve the aircraft’s capabilities in air-to-air combat, an American AN/APG-30 range-finding radar was fitted, mounted to the center of the air intake (under a slightly enlarged radome) and linked with the gyroscopic gunsight in the cockpit. It was effective at a range of up to 2.750 m, but only covered a narrow cone directly in front of the aircraft. Initially the aircraft were operated as pure fighters/interceptors, but soon they also took over ground attack and CAS missions with iron bombs and unguided missiles, even though the Mystère IV’s ordnance capacity was rather limited. But the aircraft had a good handling at low altitude and were a stable weapon platform, so that the pilots operated them with confidence.
In the early Seventies, Ecuador had plans to upgrade its Mystères with Pratt & Whitney J48-P-5 engines, a license-built version of the Rolls-Royce Tay from the USA and outfitted with an afterburner. With reheat the J48 delivered 8,750 lbf (38.9 kN) of thrust, but continuous dry thrust was only 6,350 lbf (28.2 kN), markedly less than the old Tay engine. The high fuel consumption with operating afterburner would have markedly limited the aircraft’s range, and this engine switch would have necessitated major modifications to the aircrafts’ tail section, so that the upgrade eventually did not come to fruition due the lack of funds and the rather limited and only temporary improvement in performance.
Nevertheless, in course of their career in Ecuador, the Mystères’ still underwent some modifications and modernizations. In the early Seventies an MLU program was carried out: the retractable pannier for unguided missiles was deleted in favor of an extra fuel tank and upgraded navigational and weapon avionics. The latter included wirings for IR-guided AIM-9B Sidewinder AAMs on the outer underwing pylons, what greatly improved the aircraft’s air-to-air capabilities. The original DEFA 552 guns were replaced with more modern DEFA 553s, which had a new feed system, a nitro-chrome plated steel barrel (which was longer than the 552’s and now protruded visibly from the openings), a forged drum casing, and improved electrical reliability. During this upgrade phase the machines also lost their original natural metal livery and they received a less conspicuous tactical NATO-style grey/green paint scheme with metallic-grey undersides.
In this form the Ecuadorean Mystère IVEs soldiered on well into the Eighties, with a very good reliability record. During their active career they even saw “hot” action on several occasions, for instance in a continuous border dispute with Peru, the so-called Paquisha War. This brief military clash over the control of three watch posts flared up in January 1981 and the Mystères became involved. The first incident was a dogfight with an A-37B of the Fuerza Aérea del Peru (FAP), launched from Guayaquil to intercept it – with no casualities, though. Several similar interception incidents happened until early February 1981, and the FAE Mystères also flew several CAS missions to repel the Peruvian Jungle Infantry and to support Ecuadorian ground forces. Despite their age, the aircrafts’ ruggedness and simplicity proved them to be reliable, and its high roll rate and good handling at low altitude made it a versatile platform that was still competitive, even though its rather sluggish acceleration turned out to be a serious weak spot, esp. in the country’s typical mountainous terrain. Its relatively low range with internal fuel only was another operational problem.
The Mystère IVEs were finally retired in 1988 and replaced by Mirage F.1C fighters from France and IAI Kfir C.7 fighter bombers from Israel.
General characteristics:
Crew: 1
Length: 12.89 m (42 ft 3 in)
Wingspan: 11.12 m (36 ft 6 in)
Height: 4.6 m (15 ft 1 in)
Wing area: 32.06 m² (345.1 sq ft)
Empty weight: 5,860 kg (12,919 lb)
Gross weight: 8,510 kg (18,761 lb)
Max takeoff weight: 9,500 kg (20,944 lb)
Powerplant:
1× Rolls-Royce Tay 250 centrifugal-flow turbojet engine with 34.32 kN (7,720 lbf) thrust
Performance:
Maximum speed: 1,110 km/h (690 mph, 600 kn) at sea level
Range: 915 km (569 mi, 494 nmi) with internal fuel only
2,280 km (1,420 mi; 1,230 nmi) with drop tanks
Service ceiling: 15,000 m (49,000 ft)
Rate of climb: 40 m/s (7,900 ft/min)
Armament:
2× 30 mm (1.18 in) DEFA 553 cannon with 150 rounds per gun
1,000 kg (2,200 lb) of payload on four underwing hardpoints, incl. bombs, rockets or drop tanks
The kit and its assembly:
A very simple project, and basically just an OOB kit in the colors of a fictional operator. The whole thing was inspired by the question: what could have been a predecessor of the Ecuadorean Mirage F.1s? Not an existential question that might pop up frequently, but I quickly decided that the Mystère IV would have been a good/plausible contender. I found this idea even more attractive when I considered a camouflage paint scheme for it, because you only get either French or Indian machines in a uniform NMF outfit or IDF Mystères in desert camouflage (either in brown/blue or the later sand/earth/green scheme).
The kit is the venerable Matchbox Mystère IVA, even though in its Revell re-boxing. It’s a very simple affair, with partly crude details like the landing gear or the dreaded “trenches” for engraved surface details, esp. on the wings. But it goes together quite well, and with some corrections and additions you get a decent model.
The kit was basically built OOB, I just added underwings pylons with some ordnance for a fighter bomber mission: a pair of drop tanks and two SNEB missile launcher pods (tanks leftover from a Sword F-94, IIRC, and the pods from a Matchbox G.91Y). A complete tub with a floor and with side consoles (origin is uncertain, though – maybe it came from an Xtrakit Supermarin Swift?) was fitted to the cockpit and the primitive OOB ejection seat was replaced with something more convincing, pimped with seatbelts (masking tape) and ejection trigger handles (thin wire).
The flaps were lowered for a more natural look, and I added small oval boundary layer fences from a BAe Hawk as a personal twist. The clumsy front wheel, originally molded onto the strut as a single piece, was replaced with something better. The main landing gear covers were replaced with thinner styrene sheet material (the OOB parts are VERY thick) and pieces from hollow steel needles were implanted into the respective fairings as gun barrels.
A thinner pitot, created from heated sprue material, was used instead of the rather massive OOB part. The ranging radar fairing in the intake was slightly enlarged with the help of white glue. And, finally, a piece of sprue was implanted into the fin’s base as a brake parachute fairing, reminiscent of the Polish Lim-6/7, license-produced MiG-17s.
Painting and markings:
Actually quite conservative, with a typical Seventies paint scheme in dark grey/dark green. I even considered a more exotic three-tone scheme but found that – together with the colorful national markings – this would look too busy. Since there is no reference for a Mystère IV in such a guise, I simply adapted the standard pattern from a Royal Air Force Supermarine Swift. For a different look than the standard RAF colors – after all, the fictional Ecuadorean Mystère IVs were painted with domestic material. I used Humbrol 75 (Bronze Green) and ModelMaster 2057 (FS 36173, USAF Neutral Grey) for a good contrast between the upper tones, with Humbrol 56 (Alu Dope) underneath.
The tail section received a burned metal look, using Revell 91 (Iron) and some graphite. The cockpit interior was painted in a very dark grey (Revell 09, Anthracite) while the landing gear became silver-grey and the wells zinc-chromate primer (Humbrol 81). For some contrast, the drop tanks became shiny aluminum (Revell 99).
The kit received a light black ink washing, primarily for the recessed panel lines, and a subtle panel post-shading – for a less uniform surface than for true weathering, I’d imagine that the aircraft would be looked after well. However, some gun soot stains around the weapon ports were added with graphite, too.
The Ecuadorean roundels and unit markings came from an Xtradecal Strikemaster sheet, the tactical codes from a Croco Decal sheet for various South-American trainers. The flag on the rudder was, due to its sweep, painted, and most stencils were taken from the Mystère’s OOB sheet or procured from an Ecuadorian Mirage V on a Carpena sheet.
Finally, the kit was sealed with matt acrylic varnish, the ordnance was added and the position lights on the wing tips were created with silver and clear paint on top of that.
Well, this was not a spectacular conversion build, rather an OOB travesty with some cosmetic changes. However, the rather classic grey/green camouflage suits the tubby aircraft well and the bright national insignia really stand out on it – a pretty combo. The whole package as fictional Mystère IVE looks surprisingly convincing!
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based historical facts. BEWARE!
Some background:
The Hawker Cyclone was an evolutionary successor to the successful Hawker Typhoon and Tempest fighters and fighter-bombers of the Second World War. The Cyclone's design process was initiated in September 1942 by Sydney Camm, one of Hawker's foremost aircraft designers, to meet the Royal Air Force’s requirement for a lightweight Tempest Mk.II and V replacement.
The project, tentatively designated Tempest Mk. VIII, was formalised in January 1943 when the Air Ministry issued Specification F.2/42 around the "Tempest Light Fighter".This was followed up by Specification F.2/43, issued in May 1943, which required a high rate of climb of not less than 4,500 ft/min (23 m/s) from ground level to 20,000 feet (6,096 m), good fighting manoeu rability and a maximum speed of at least 450 mph (724 km/h) at 22,000 feet (6,705 m). The armament was to be four 20mm Hispano V cannon with a total capacity of 600 rounds, plus the capability of carrying two bombs each up to 1,000 pounds (454 kg). In April 1943, Hawker had also received Specification N.7/43 from the Admiralty, who sought a navalized version of the developing aircraft, what eventually led to the Hawker Sea Fury, which was a completely new aircraft, which only shared the general outlines of the Tempest.
The Royal Air Force was looking for a quicker solution, and Camm started working on a new laminar flow wing, which would further improve the Tempest’s speed. Further refinements were done to other aerodynamic components, too, like the radiator, since the Tempest V’s liquid-cooled Napier Sabre engine was to be used. After some experiments with new arrangements, an annular radiator directly behind the propeller was chosen – certainly inspired by fast German aircraft like the Fw 190D and developed by Napier.
A total of three prototypes were ordered; the first one was powered by a Napier Sabre IIA liquid-cooled H-24 sleeve-valve engine, generating 2,180 hp (1,625 kW), but the second and any following aircraft carried the more powerful Sabre V with 2,340 hp, driving a Rotol four-blade propeller. Later aircraft were even to carry the Napier Sabre VII, which was capable of developing 3,400–4,000 hp (2,535–2,983 kW) and pushing the top speed to 485 mph (780 km/h) and more. The third airframe was just a static test structure. However, since the differences between the Tempest and the new aircraft had become almost as big as to its predecessor, the Typhoon, the new type received its own name Cyclone.
The first Cyclone Mk. I to fly, on 30 August 1944, was NV950, and it became clear soon that the modifications would improve the Cyclone’s top speed vs. the Tempest by almost 30 mph (50 km/h), but the new components would also require a longer testing period than expected. The annular radiator frequently failed and overheated, and the new, slender wings caused directional stability problems so that the complete tail section had to be re-designed. This troubling phase took more than 6 months, so that eventual service aircraft would only be ready in mid-1945 – too late for any serious impact in the conflict.
However, since the Hawker Fury, the land-based variant of the Sea Fury, which had been developed from the Tempest for the Royal Navy in parallel, had been cancelled, the Royal Air Force still ordered 150 Cyclone fighters (F Mk. I), of which one third would also carry cameras and other reconnaissance equipment (as Cyclone FR Mk.II). Due to the end of hostilities in late 1945, this order immediately lost priority. Consequently, the first production Cyclone fighters were delivered in summer 1946 – and in the meantime, jet fighters had rendered the piston-powered fighters obsolete, at least in RAF service. As a consequence, all Cyclones were handed over to friendly Commonwealth nations and their nascent air forces, e. g. India, Thailand or Burma. India received its first Cyclones in late 1947, just when the Kashmir conflict with Pakistan entered a hot phase. The machines became quickly involved in this conflict from early 1948 onwards.
Cyclones played an important role in the strikes against hostiles at Pir Badesar and the dominating Pir Kalewa. The taking of Ramgarh fort and Pt. 6944 on the west flank of Bhimbar Gali was to be a classic close support action with Indian forces carrying out a final bayonet charge against the enemy trenches whilst RIAF Cyclones and Tempests strafed and rocketed the trenches at close quarters. On a chance reconnaissance, enemy airfields were located at Gilgit and 40 NMs south, at Chilas. Cyclones flew several strikes against the landing strips in Oct and Nov 48, cratering & damaging both and destroying several hangars, barracks and radio installations. This attack destroyed Pakistani plans to build an offensive air capability in the North. Already, with Tempests and Cyclones prowling the valleys, Pakistani re-supply by Dakotas had been limited to hazardous night flying through the valleys.
After the end of hostilities in late 1948 and the ensuing independence, the Cyclone squadrons settled into their peace time stations. However, constant engine troubles (particularly the radiator) continued to claim aircraft and lives and the skill required to land the Cyclone because of its high approach speed continued to cause several write offs. The arrival of the jet-engined Vampire were the first signs of the Cyclone’s demise. As the IAF began a rapid expansion to an all jet force, several Tempest and Cyclone squadrons began converting to Vampires, 7 Squadron being the first in Dec 49. By this time it had already been decided that the piston-engine fighters would be relegated to the fighter lead-in role to train pilots for the new jet fighters. A conversion training flight was set up at Ambala in Sep 49 with Spitfire T Mk IXs, XVIIIs and Tempests to provide 16 hrs/six weeks of supervised Tempest training. This unit eventually moved to Hakimpet two years later and operated till the end of 1952. Some Cyclone FR Mk. IIs remained in front line service until 1954, though.
General characteristics:
Crew: One
Length: 35 ft 5 3/4 in (10.83 m)
Wingspan: 42 ft 5 1/2 in (12.96 m)
Height (tail down): 15 ft 6 3/4 in (4.75 m)
Wing area: 302 ft² (28 m²)
Empty weight: 9,250 lb (4,195 kg)
Loaded weight: 11,400 lb (5,176 kg)
Max. takeoff weight: 13,640 lb (6,190 kg)
Powerplant:
1× Napier Sabre V liquid-cooled H-24 sleeve-valve engine with 2,340 hp (1,683 kW)
Performance:
Maximum speed: 460 mph (740 km/h) 18,400 ft (5,608 m),
Range: 740 mi (1,190 km)
1,530 mi (2,462 km) with two 90 gal (409 l) drop tanks
Service ceiling: 36,500 ft (11,125 m)
Rate of climb: 4,700 ft/min (23.9 m/s)
Wing loading: 37.75 lb/ft² (184.86 kg/m²)
Power/mass: 0.21 hp/lb (0.31 kW/kg)
Armament:
4× 20 mm (.79 in) Mark V Hispano cannons, 200 RPG
2× underwing hardpoints for 500 lb (227 kg) or 1,000 lb (454 kg) bombs
or 2 × 45 gal (205 l) or 2 × 90 gal (409 l) drop tanks
plus 6× 3” (76.2 mm) RP-3 rockets
The kit and its assembly:
Another episode in the series “Things to make and do with Supermarine Attacker wings”. And what started as a simple switch of wings eventually turned into a major kitbashing, since the model evolved from a modded Tempest into something more complex and conclusive.
The initial spark was the idea of a Hawker alternative to Supermarine’s Spiteful and Seafang developments – especially with their slender laminar flow wings. Wouldn’t a Hawker alternative make sense?
Said and done, I dug out a NOVO Attacker kit and a Matchbox Tempest, and started measuring – and the wing transplantation appeared feasible! I made the cut on the Tempest wing just outside of the oil cooler, and the Attacker wings were then attached to these stubs – after some gaps for the landing gear wells had been cut into the massive lower wing halves. The stunt went more smoothly than expected, the only cosmetic flaw is that the guns went pretty far outboard, but that’s negligible.
But the different wings were not enough. I had recently seen in a book a picture of a Tempest (NV 768) with an experimental annular radiator for the Sabre engine (looking like a streamlined Tempest II), and wondered if this arrangement would have been the aerodynamically more efficient solution than the bulbous chin radiator of the Tempest V and VI? I decided to integrate this feature into my build, too, even though not as a copy of the real-world arrangement. The whole nose section, even though based on the OOB Mk. V nose, was scratched and re-sculpted with lots of putty. The radiator intake comes from a FROG He 219, with the front end opened and a fan from a Matchbox Fw 190 placed inside, as well as a styrene tube for the new propeller. The latter was scratched, too, from a Matchbox He 70 spinner and single blades from an Italeri F4U, plus a metal axis. The exhaust stubs were taken OOB, but their attachment slits had to be re-engraved into the new and almost massive nose section.
Once the wings and the nose became more concrete, I found that the Tempest’s original rounded tail surfaces would not match with the new, square wings. Therefore I replaced the stabilizers with donations from a Heller F-84G and modified the fin with a new, square tip (from an Intech Fw 190D) and got rid of the fin fillet – both just small modifications, but they change the Tempest’s profile thoroughly.
In order to underline the aircraft’s new, sleek lines, I left away any ordnance – but instead I added some camera fairings: one under the rear fuselage or a pair of vertical/oblique cameras, and another camera window portside for a horizontal camera. The openings were drilled, and, after painting, the kit the camera windows were created with Humbrol Clearfix.
Painting and markings:
Somehow I thought that this aircraft had to carry Indian markings – and I had a set of standard Chakra Wheels from the late Forties period in my stash. The camouflage is, typical for early IAF machines of British origin, RAF standard, with Dark Green and Ocean Grey from above and Medium Sea Grey from below. I just used the more brownish pst-war RAF Dark Green tone (Humbrol 163), coupled with the rather light Ocean Grey from Modelmaster (2057). The underside became Humbrol 165. All interior surfaces were painted with RAF Interior Green, nothing fancy. The only colorful addition is the saffron-colored spinner, in an attempt to match the fin flash’s tone.
As a standard measure, the kit received a black ink wash and some panel post-shading with lighter tones – only subtly, since the machine was not to look too weathered and beaten, just used from its Kashmir involvements.
The national markings come from a Printscale Airspeed Oxford sheet, the tactical code with alternating white and black letters, depending on the underground (the sky fuselage band comes from a Matchbox Brewster Buffalo), was puzzled together from single letters from TL Modellbau – both seen on different contemporary RIAF aircraft.
As another, small individual detail I gave the machine a tactical code letter on the fuselage, and the small tiger emblems under the cockpit were home-printed from the official IAF No. 1 Squadron badge.
Despite the massive modifications this one is a relatively subtle result, all the changes become only visible at a second glance. A sleek aircraft, and from certain angley the Cyclone looks like an A-1 Skyraider on a diet?
The mountain gorilla (Gorilla beringei beringei) is one of the two subspecies of the eastern gorilla. There are two populations. One is found in the Virunga volcanic mountains of Central Africa, within three National Parks: Mgahinga, in south-west Uganda; Volcanoes, in north-west Rwanda; and Virunga in the eastern Democratic Republic of Congo (DRC). It is listed as critically endangered by the IUCN. The other is found in Uganda's Bwindi Impenetrable National Park. Some primatologists consider the Bwindi population in Uganda may be a separate subspecies,[3] though no description has been finalized. As of September 2016, the estimated number of mountain gorillas remaining is about 880.[4]
Gorilla taxonomy
Mountain gorillas are descendants of ancestral monkeys and apes found in Africa and Arabia during the start of the Oligocene epoch (34-24 million years ago). The fossil record provides evidence of the hominoid primates (apes) found in east Africa about 22–32 million years ago. The fossil record of the area where mountain gorillas live is particularly poor and so its evolutionary history is not clear.[5] It was about 9 million years ago that the group of primates that were to evolve into gorillas split from their common ancestor with humans and chimps; this is when the genus Gorilla emerged. It is not certain what this early relative of the gorilla was, but it is traced back to the early ape Proconsul africanus.[6] Mountain gorillas have been isolated from eastern lowland gorillas for about 400,000 years and these two taxa separated from their western counterparts approximately 2 million years ago.[7] There has been considerable and as yet unresolved debate over the classification of mountain gorillas. The genus was first referenced as Troglodytes in 1847, but renamed to Gorilla in 1852. It was not until 1967 that the taxonomist Colin Groves proposed that all gorillas be regarded as one species (Gorilla gorilla) with three sub-species Gorilla gorilla gorilla (western lowland gorilla), Gorilla gorilla graueri (lowland gorillas found west of the Virungas) and Gorilla gorilla beringei (mountain gorillas including, Gorilla beringei found in the Virungas and Bwindi). In 2003 after a review they were divided into two species (Gorilla gorilla and Gorilla beringei) by The World Conservation Union (IUCN).[5]
Physical description
Silverback of Ntambara group, in typical resting attitude.
The fur of the mountain gorilla, often thicker and longer than that of other gorilla species, enables them to live in colder temperatures.[8] Gorillas can be identified by nose prints unique to each individual.[9] Males, at a mean weight of 195 kg (430 lb) upright standing height of 150 cm (59 in) usually weigh twice as much as the females, at a mean of 100 kg (220 lb) and a height of 130 cm (51 in).[10] This subspecies is on average the second largest species of primate; only the eastern lowland gorilla, the other subspecies of eastern gorilla, is larger.[citation needed] Adult males have more pronounced bony crests on the top and back of their skulls, giving their heads a more conical shape. These crests anchor the powerful temporalis muscles, which attach to the lower jaw (mandible). Adult females also have these crests, but they are less pronounced.[9] Like all gorillas they feature dark brown eyes framed by a black ring around the iris. Adult males are called silverbacks because a saddle of gray or silver-colored hair develops on their backs with age. The hair on their backs is shorter than on most other body parts, and their arm hair is especially long. Fully erect, males reach 1.9 m (6 ft 3 in) in height, with an arm span of 2.6 m (8 ft 6 in) and weigh 220 kg (490 lb).[11] The tallest silverback recorded was a 1.94 m (6 ft 4 in) with an arm span of 2.7 m (8 ft 10 in), a chest of 1.98 m (6 ft 6 in), and a weight of 219 kg (483 lb), shot in Alimbongo, northern Kivu in May 1938. There is an unconfirmed record of another individual, shot in 1932, that was 2.06 m (6 ft 9 in) and weighed 218.6 kg (482 lb).
The mountain gorilla is primarily terrestrial and quadrupedal. However, it will climb into fruiting trees if the branches can carry its weight, and it is capable of running bipedally up to 6 m (20 ft).[citation needed] Like all great apes other than humans, its arms are longer than its legs. It moves by knuckle-walking (like the common chimpanzee, but unlike the bonobo and both orangutan species), supporting its weight on the backs of its curved fingers rather than its palms.[citation needed]
The mountain gorilla is diurnal, most active between 6:00 a.m. and 6:00 p.m.[citation needed] Many of these hours are spent eating, as large quantities of food are needed to sustain its massive bulk. It forages in early morning, rests during the late morning and around midday, and in the afternoon it forages again before resting at night. Each gorilla builds a nest from surrounding vegetation to sleep in, constructing a new one every evening. Only infants sleep in the same nest as their mothers. They leave their sleeping sites when the sun rises at around 6 am, except when it is cold and overcast; then they often stay longer in their nests.[12]
Habitat and ecology
Adult male feeding on insects in a rotting tree trunk
The mountain gorilla inhabits the Albertine Rift montane cloud forests and of the Virunga Volcanoes, ranging in altitude from 2,200–4,300 metres (7,200–14,100 ft). Most are found on the slopes of three of the dormant volcanoes: Karisimbi, Mikeno, and Visoke.[13] The vegetation is very dense at the bottom of the mountains, becoming more sparse at higher elevations, and the forests where the mountain gorilla lives are often cloudy, misty and cold.[14]
The mountain gorilla is primarily a herbivore; the majority of its diet is composed of the leaves, shoots and stems (85.8%) of 142 plant species. It also feeds on bark (6.9%), roots (3.3%), flowers (2.3%), and fruit (1.7%), as well as small invertebrates. (0.1%).[15] Adult males can eat up to 34 kilograms (75 lb) of vegetation a day, while a female can eat as much as 18 kilograms (40 lb).[citation needed]
The home range size (the area used by one group of gorillas during one year) is influenced by availability of food sources and usually includes several vegetation zones. George Schaller identified ten distinct zones, including: the bamboo forests at 2,200–2,800 metres (7,200–9,200 ft); the Hagenia forests at 2,800–3,400 metres (9,200–11,200 ft); and the giant senecio zone at 3,400–4,300 metres (11,200–14,100 ft).[12] The mountain gorilla spends most of its time in the Hagenia forests, where galium vines are found year-round. All parts of this vine are consumed: leaves, stems, flowers, and berries. It travels to the bamboo forests during the few months of the year fresh shoots are available, and it climbs into subalpine regions to eat the soft centers of giant senecio trees.[13]
Behaviour
Social structure
The mountain gorilla is highly social, and lives in relatively stable, cohesive groups held together by long-term bonds between adult males and females. Relationships among females are relatively weak.[16] These groups are nonterritorial; the silverback generally defends his group rather than his territory. In the Virunga mountain gorillas, the average length of tenure for a dominant silverback is 4.7 years.[17]
61% of groups are composed of one adult male and a number of females and 36% contain more than one adult male. The remaining gorillas are either lone males or exclusively male groups, usually made up of one mature male and a few younger males.[18] Group sizes vary from five to thirty, with an average of ten individuals. A typical group contains: one dominant silverback, who is the group's undisputed leader; another subordinate silverback (usually a younger brother, half-brother, or even an adult son of the dominant silverback); one or two blackbacks, who act as sentries; three to four sexually mature females, who are ordinarily bonded to the dominant silverback for life; and from three to six juveniles and infants.[19]
Most males, and about 60% of females, leave their natal group. Males leave when they are about 11 years old, and often the separation process is slow: they spend more and more time on the edge of the group until they leave altogether.[20] They may travel alone or with an all-male group for 2–5 years before they can attract females to join them and form a new group. Females typically emigrate when they are about 8 years old, either transferring directly to an established group or beginning a new one with a lone male. Females often transfer to a new group several times before they settle down with a certain silverback male.[21]
The dominant silverback generally determines the movements of the group, leading it to appropriate feeding sites throughout the year. He also mediates conflicts within the group and protects it from external threats.[14] When the group is attacked by humans, leopards, or other gorillas, the silverback will protect them even at the cost of his own life.[22] He is the center of attention during rest sessions, and young animals frequently stay close to him and include him in their games. If a mother dies or leaves the group, the silverback is usually the one who looks after her abandoned offspring, even allowing them to sleep in his nest.[23] Experienced silverbacks are capable of removing poachers' snares from the hands or feet of their group members.[24]
When the silverback dies or is killed by disease, accident, or poachers, the family group may be disrupted.[13] Unless there is an accepted male descendant capable of taking over his position, the group will either split up or adopt an unrelated male. When a new silverback joins the family group, he may kill all of the infants of the dead silverback.[25] Infanticide has not been observed in stable groups.
Analysis of mountain gorilla genomes by whole genome sequencing indicates that a recent decline in their population size has led to extensive inbreeding.[26] As an apparent result, individuals are typically homozygous for 34% of their genome sequence. Furthermore, homozygosity and the expression of deleterious recessive mutations as consequences of inbreeding have likely resulted in the purging of severely deleterious mutations from the population.
Aggression
Although strong and powerful, the mountain gorillas are generally gentle and very shy.[22] Severe aggression is rare in stable groups, but when two mountain gorilla groups meet, the two silverbacks can sometimes engage in a fight to the death, using their canines to cause deep, gaping injuries.[19] For this reason, conflicts are most often resolved by displays and other threat behaviors that are intended to intimidate without becoming physical. The ritualized charge display is unique to gorillas. The entire sequence has nine steps: (1) progressively quickening hooting, (2) symbolic feeding, (3) rising bipedally, (4) throwing vegetation, (5) chest-beating with cupped hands, (6) one leg kick, (7) sideways running four-legged, (8) slapping and tearing vegetation, and (9) thumping the ground with palms .[27] Jill Donisthorpe stated that a male charged at her twice. In both cases the gorilla turned away, when she stood her ground.
Volcanoes National Park (French: Parc National des Volcans) lies in northwestern Rwanda and borders Virunga National Park in the Democratic Republic of Congo and Mgahinga Gorilla National Park in Uganda. The national park is known as a haven for the mountain gorilla. It is home to five of the eight volcanoes of the Virunga Mountains (Karisimbi, Bisoke, Muhabura, Gahinga and Sabyinyo), which are covered in rainforest and bamboo. The park was the base for the zoologist Dian Fossey.
History
Children on a farm near Volcanoes National Park
The park was first gazetted in 1925, as a small area bounded by Karisimbi, Visoke and Mikeno, intended to protect the gorillas from poachers. It was the very first National Park to be created in Africa. Subsequently, in 1929, the borders of the park were extended further into Rwanda and into the Belgian Congo, to form the Albert National Park, a huge area of 8090 km2, run by the Belgian colonial authorities who were in charge of both colonies.[1] In 1958, 700 hectares of the park were cleared for a human settlement.[2]
After the Congo gained independence in 1960, the park was split into two, and upon Rwandan independence in 1962 the new government agreed to maintain the park as a conservation and tourist area, despite the fact that the new republic was already suffering from overpopulation problems. The park was halved in area in 1969.[citation needed] Between 1969 and 1973, 1050 hectares of the park were cleared to grow pyrethrum.[2]
The park later became the base for the American naturalist Dian Fossey to carry out her research into the gorillas. She arrived in 1967 and set up the Karisoke Research Centre between Karisimbi and Visoke. From then on she spent most of her time in the park, and is widely credited with saving the gorillas from extinction by bringing their plight to the attention of the international community. She was murdered by unknown assailants at her home in 1985, a crime often attributed to the poachers she had spent her life fighting against.[3] Fossey's life later was portrayed on the big screen in the film Gorillas in the Mist, named after her autobiography. She is buried in the park in a grave close to the research center, and amongst the gorillas which became her life.
The Volcanoes National Park became a battlefield during the Rwandan Civil War, with the park headquarters being attacked in 1992. The research centre was abandoned, and all tourist activities (including visiting the gorillas) were stopped. They did not resume again until 1999 when the area was deemed to be safe and under control. There have been occasional infiltrations by Rwandan rebels from the Democratic Forces for the Liberation of Rwanda in subsequent years, but these are always stopped quickly by the Rwandan army and there is thought to be no threat to tourism in the park.
Flora
Vegetation varies considerably due to the large altitudinal range within the park. There is some lower montane forest (now mainly lost to agriculture). Between 2400 and 2500 m, there is Neoboutonia forest. From 2500 to 3200 m Arundinaria alpina (bamboo) forest occurs, covering about 30% of the park area. From 2600 to 3600 m, mainly on the more humid slopes in the south and west, is Hagenia-Hypericum forest, which covers about 30% of the park. This is one of the largest forests of Hagenia abyssinica. The vegetation from 3500 to 4200 m is characterised by Lobelia wollastonii, L. lanurensis, and Senecio erici-rosenii and covers about 25% of the park. From 4300 to 4500 m grassland occurs. Secondary thicket, meadows, marshes, swamps and small lakes also occur, but their total area is relatively small.
Fauna
The park is best known for the mountain gorilla (Gorilla beringei beringei). Other mammals include: golden monkey (Cercopithecus mitis kandti), black-fronted duiker (Cephalophus niger), buffalo (Syncerus caffer), spotted hyena (Crocuta crocuta) and bushbuck (Tragelaphus scriptus). There are also reported to be some elephants in the park, though these are now very rare.[4] There are 178 recorded bird species, with at least 13 species and 16 subspecies endemic to the Virunga and Ruwenzori Mountains.[5]
Tourism in the park
Young gorilla grabs tourist at Volcanoes National Park
The Rwanda Development Board (RDB) runs several activities for tourists, including:[6]
Gorilla visits - as of January 2015, there are ten habituated gorilla groups open to tourists, allowing for a total of 80 permits per day. Tourists report at the park head office by 7:00 for a pre-tracking briefing. Once tourists meet the gorillas they spend an hour with them.
Golden monkey visits.
Climbing of Karisimbi volcano - this is a two-day trek with overnight camping at an altitude of 3,800 m.
Climbing of Bisoke volcano - one day.
Tour of the lakes and caves.
Visiting the tomb of Dian Fossey.
Iby’Iwacu cultural village tour
The majority of revenue from tourism goes towards maintaining the park and conserving the wildlife. The remainder goes to the government and (around 10%)[citation needed] to local projects in the area to help local people benefit from the large revenue stream generated by the park.
This is an extraordinarily attractive female of the species, Homo Sapien. What emerges out of the proximity of the male and the female pictured here is likely nothing. Natural selection will mean that the tendency is for this female example of the species to mate with a male that in some ways is an equal counterbalance to her powerful genes and that probably excludes the hapless chap in the shot even if he tried hs luck, (You'll never know.)
The purpose of all this monkey business, if purpose is the word, is for both males and females to best express their genes into the future. Best, in this scientific sense, means offspring most likely to survive, thrive, and in turn pass on their genes. The future, however, is not particularily predictable. Thus, this particular ape-like species, has evolved a non-monagamous approach to the evolutionay problem as both the females and the males are hard-wired to express their genes with more than one mate. Even for the males who wins the right to mate with even this lovely female, after some time they will have an itch to move on. That might be after an night or years. (Recent studies indicate the move-on itch strikes quite hard after about four years for both males and females and that corresponds to the age when a human baby has developed the capacity communicate his or her needs to adults.)
Humans are an unusually sexual species and like its closest relative the Bonobo Pygmy Chimp it mates even when the female is not fertile and for many different reasons. Reasons such as devloping strategic aliances within a group or creating loyalty have been suggested so as to explain why Humans are so sexual. Predictably the same basic sexual selection hard-wireing that is in male brains is in female brains, although for her sociological factors at least within this society still make that self-realization harder for her to admit than him - or so it was until recently. (One term for this mode of female psychology is 'romance'.) Also for this species when for social-economic reason parents become the main rearers of children, as oposed to tribal female elders or extended familly members, monogamy is obviously a strategy that gains considerable utility.
en.wikipedia.org/wiki/Great_reed_warbler
The great reed warbler (Acrocephalus arundinaceus) is a Eurasian passerine in the genus Acrocephalus. It used to be placed in the Old World warbler assemblage, but is now recognized as part of the marsh and tree-warbler family (Acrocephalidae). A. arundinaceus are medium-sized birds and are the largest of the European warblers. They breed throughout mainland Europe and Asia and migrate to sub-Saharan Africa in the winter. Great reed warblers favor reed beds as their habitat during breeding months, while living in reed beds, bush thickets, rice fields, and forest clearings during the winter. Great reed warblers exhibit relatively low sexual dimorphism, and both genders of the species are similar in appearance. This species mates both polygynously and monogamously.
Description
The thrush-sized warbler is one of the largest species of Old World warbler. It measures 16–21 cm (6.3–8.3 in) in length, 25 to 30 cm (9.8 to 11.8 in) in wingspan and weighs 22 to 38 g (0.78 to 1.34 oz).[2][3][4] The adult has unstreaked brown upperparts and dull buffish-white chin and underparts. The forehead is flattened, and the bill is strong and pointed. It looks very much like a giant Eurasian reed warbler (A. scirpaceus), but with a stronger supercilium.
The sexes are identical, as with most old world warblers, but young birds are richer buff below.
The warbler's song is very loud and far-carrying. The song's main phrase is a chattering and creaking carr-carr-cree-cree-cree-jet-jet, to which the whistles and vocal mimicry typical of marsh warblers are added.
Distribution and ecology
A. arundinaceus breeds in Europe and westernmost temperate Asia. It does not breed in Great Britain, but is a regular visitor. Its population has in recent decades increased around the eastern Baltic Sea, while it has become rarer at the western end of its range. It is a migratory bird, wintering in tropical Africa. This bird migrates north at a rather late date, and some birds remain in their winter quarters until the end of April.[1][5][6]
While there are no subspecies of this bird, mtDNA haplotype data indicate that during the last glacial period there were two allopatric populations of A. arundinaceus. The great reed warblers in southwestern and southeastern Europe were at that time apparently separated by the Vistulian-Würm ice sheets and the surrounding barren lands. Though the data are insufficient to robustly infer a date for this separation, it suggests the populations became separated around 80,000 years ago – coincident with the first major advance of the ice sheets. The populations must have expanded their range again at the start of the Holocene about 13,000 years ago, but even today the western birds winter in the west and the eastern birds in the east of tropical Africa.[6]
This passerine bird is found in large reed beds, often with some bushes. On their breeding grounds, they are territorial. In their winter quarters, they are frequently found in large groups, and may occupy a reed bed to the exclusion of other birds.[5] Like most warblers, it is insectivorous, but it will take other prey items of small size, including vertebrates such as tadpoles.
The great reed warbler undergoes marked long-term population fluctuations, and it is able to expand its range quickly when new habitat becomes available. This common and widespread bird is considered a species of least concern by the IUCN.[
Behavior
Diet
Communication and courtship
Male great reed warblers have been observed to communicate via two basic song types: short songs about one second in length with few syllables, and long songs of about four seconds that have more syllables and are louder than the short variety. It has been observed that long songs are primarily used by males to attract females; long songs are only given spontaneously by unpaired males, and cease with the arrival of a female. Short songs, however, are primarily used in territorial encounters with rival males.[10]
During experimental observation, male great reed warblers showed reluctance to approach recordings of short songs, and when lured in by long songs, would retreat when playback was switched to short songs.[10]
Traditionally, monogamous species of genus Acrocephalus use long, variable, and complex songs to attract mates, whereas polygynous varieties use short, simple, stereotypical songs for territorial defense. There is evidence that long songs have been evolved through intersexual selection, whereas short songs have been evolved through intrasexual selection. “A. arundinaceus” is a notable example of these selective pressures, as it is a partial polygynist and has evolved variable song structure (both long and short) through evolutionary compromise.[10]
In addition to communication, the great reed warbler’s song size has been implicated in organism fitness and reproductive success. Though no direct relationship has been found between song size and either territory size or beneficial male qualities, such as wing length, weight, or age, strong correlation has been observed between repertoire size and territory quality. Furthermore, partial correlation analysis has shown that territory quality has significant effect on number of females obtained, while repertoire length is linked to the number of young produced.[11]
Mating system and sexual behavior
A. arundinaceus females lay 3–6 eggs in a basket nest in reeds. Some pairs of warblers are monogamous, but others are not, and unpaired, territory-less males still father some young.[12]
A long-term study of the factors that contribute to male fitness examined the characteristics of males and territories in relation to annual and lifetime breeding success. It showed that the arrival order of the male was the most significant factor for predicting pairing success, fledgling success, and number of offspring that survive. It also found that arrival order was closely correlated with territory attractiveness rank. Females seem to prefer early arriving males that occupy more attractive territories. These females also tend to gain direct benefits through the increased production of fledglings and offspring that become adults. In addition, male song repertoire length is positively correlated to annual harem size and overall lifetime production of offspring that survive. Song repertoire size alone is able to predict male lifetime number of surviving offspring. Females tend to be attracted to males with longer song repertoires since they tend to sire offspring with improved viability. In doing so, they gain indirect benefits for their own young.[13][14]
Great reed warblers have a short, polygynous breeding cycle in which the male contributes little to parental care. They defend large territories in reed beds where there is reduced visibility, which may allow males to practice deception by moving and attracting a second female. This second female may not realize that the male has already mated. Polygyny of the great reed warbler was assessed in another study that showed the importance of female choice. The differences in territory characteristics seemed to be more important. However, there is also a strong correlation between male and their territory characteristics. Models based on the polygyny threshold and sexy son hypotheses predict that females should gain evolutionary advantage in either short-term or long-term in this mating system, yet the study did not support this. The data showed that secondary females had greatly reduced breeding success
“The central nervous system is nature’s Sistine Chapel, but we have to bear in mind that the world our senses present to us – this office, my lab, our awareness of time – is a ramshackle construct which our brains have devised to let us get on with the job of maintaining ourselves and reproducing our species. What we see is a highly conventionalised picture, a simple tourist guide to a very strange city. We need to dismantle this ramshackle construct in order to grasp what’s really going on.” - J.G. Ballard, 1992
This article was originally published by the Art X Neuroscience (AXNS) Collective in May 2016, and has now been re-published by Clot Magazine (in slightly up-dated form). This article summarises material featured in chapter 4 of the book “Rorschach Audio – Art & Illusion for Sound”, first published in June 2012, in an article printed on page 16 of “The Starry Rubric Set”, published by Wysing Arts Centre in Feb 2012, and on pages 17 and 18 of Shoppinghour Magazine, issue 10, Spring 2013.
Article [see link] copyright © Joe Banks – May 2016 + Oct 2022
Feature in Clot Magazine – tinyurl.com/mr7vxmtk
Video on the sound installation aspect of “The Analysis of Beauty” –
www.flickr.com/disinfo/47923588897/
“The Analysis of Beauty” by Disinformation has been exhibited at the Freud Museum (London) June 2015, the Georgian Gallery at Talbot Rice (Edinburgh) Nov 2014, at Saltburn Artists Projects, Jan 2007, the Wrexham Arts Centre, Oct 2006, at the Mac (Birmingham) July 2005, Orleans House Gallery (Twickenham) Nov 2004, the Quad (Derby) June 2004, South Hill Park (Bracknell) April 2004, Quay Arts (Isle of Wight) Feb 2004, the Ashcroft Arts Centre (Fareham) Sept 2003, Huddersfield Art Gallery, Jan 2003, the Royal Society of Sculptors (London) March 2001, and Kettle’s Yard (Cambridge) Jan 2000.
Kettle’s Yard (2000) - www.flickr.com/disinfo/32159928382/
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
Some background:
When Marcel Dassault started work on jet-powered fighters after WWII, the development evolved in gradual steps instead of quantum leaps, leading to a long line of aircraft. The Mystère IV was an evolutionary development of the Mystère II aircraft. Although bearing an external resemblance to the earlier aircraft, the Mystère IV was in fact a new design with aerodynamic improvements for supersonic flight. The prototype first flew on 28 September 1952, and the aircraft entered service in April 1953. The first 50 Mystere IVA production aircraft were powered by British Rolls-Royce Tay turbojets, while the remainder had the French-built Hispano-Suiza Verdon 350 version of that engine.
France was the main operator of the Mystère IV. In April 1953 the United States government and the United States Air Force placed an order for 223 aircraft to be operated by the French, and at the peak usage the Armée de l‘air operated 6 squadrons. Most of the aircraft were purchased under a United States Offshore Procurement contract and many were returned to US custody after they were retired. The Mystère IVs were used in the 1956 Suez Crisis and continued to remain in French service into the 1980s, even though they were quickly relegated into second line duties as more capable types like the Super Mystère SM2B or the Mirage III entered service.
Other international operators included Israel (using about sixty Mystère IVs in large-scale combat during the 1967 Six Day War), India (104 aircraft procured in 1957 and extensively used in the Indo-Pakistani War of 1965) and Ecuador.
The Fuerza Aérea Ecuatoriana (FAE, Ecuadorian Air Force) was officially created on October 27, 1920. However, like in many other countries, military flying activity already started before the formal date of birth of the Air Force. By 1939 the Ecuadorian Air Force was still limited to about 30 aircraft, though, and a staff of about 60, including 10 officers. Military aviation did not start in earnest until the early forties when an Ecuadorian mission to the United States resulted in the delivery of an assortment of aircraft for the Aviation school at Salinas: three Ryan PT-22 Recruits, six Curtiss-Wright CW-22 Falcons, six Fairchild PT-19A Cornells and three North American AT-6A Harvards arrived in March 1942, considerably boosting the capacity of the Escuela de Aviación at Salinas.
The 1950s and 1960s saw a further necessary buildup of the air force, gaining more units and aircraft, while efforts were made in enhancing the facilities at various airbases. In May 1961 the "First Air Zone" with its subordinate unit Ala de Transportes No.11 was founded. The "Second Air Zone" controlled the units in the southern half of Ecuador, Ala de Combate No.21 at Taura, Ala de Rescate No.22 at Guayaquil and Ala de Combate No.23 at Manta as well as the Escuela Superior Militar de Aviación "Cosme Rennella B." (ESMA) at Salinas.
It was at this time that the FAE was looking for a capable (yet affordable) jet fighter that would replace the vintage F-47 “Thunderbolt” piston engine fighters of American origin that had been operated since 1947 as well as the ageing fleet of Gloster Meteor jet fighters. After consulting various options, including the British Hawker Hunter and the American F-86 Sabre, Ecuador settled upon the French Mystère IV. A total of 32 aircraft were ordered in 1958 and delivered until early 1963 in two tranches, subsequently outfitting two combat squadrons.
The Ecuadorian aircraft resembled the early French Mystère IV standard and were powered by the British Rolls-Royce Tay 250. However, they differed in small details and incorporated some updates, leading to the individual designation Mystère IVE (for Ecuador). This included a modified instrumentation and a British Martin Baker ejection seat in the cockpit. On the outside, a fairing for a brake parachute at the fin’s base was the most obvious change, and there were small oval boundary layer fences on the wings’ leading edges that improved the aircraft’s handling. The front landing gear was slightly different, too, now outfitted with a mudguard.
To improve the aircraft’s capabilities in air-to-air combat, an American AN/APG-30 range-finding radar was fitted, mounted to the center of the air intake (under a slightly enlarged radome) and linked with the gyroscopic gunsight in the cockpit. It was effective at a range of up to 2.750 m, but only covered a narrow cone directly in front of the aircraft. Initially the aircraft were operated as pure fighters/interceptors, but soon they also took over ground attack and CAS missions with iron bombs and unguided missiles, even though the Mystère IV’s ordnance capacity was rather limited. But the aircraft had a good handling at low altitude and were a stable weapon platform, so that the pilots operated them with confidence.
In the early Seventies, Ecuador had plans to upgrade its Mystères with Pratt & Whitney J48-P-5 engines, a license-built version of the Rolls-Royce Tay from the USA and outfitted with an afterburner. With reheat the J48 delivered 8,750 lbf (38.9 kN) of thrust, but continuous dry thrust was only 6,350 lbf (28.2 kN), markedly less than the old Tay engine. The high fuel consumption with operating afterburner would have markedly limited the aircraft’s range, and this engine switch would have necessitated major modifications to the aircrafts’ tail section, so that the upgrade eventually did not come to fruition due the lack of funds and the rather limited and only temporary improvement in performance.
Nevertheless, in course of their career in Ecuador, the Mystères’ still underwent some modifications and modernizations. In the early Seventies an MLU program was carried out: the retractable pannier for unguided missiles was deleted in favor of an extra fuel tank and upgraded navigational and weapon avionics. The latter included wirings for IR-guided AIM-9B Sidewinder AAMs on the outer underwing pylons, what greatly improved the aircraft’s air-to-air capabilities. The original DEFA 552 guns were replaced with more modern DEFA 553s, which had a new feed system, a nitro-chrome plated steel barrel (which was longer than the 552’s and now protruded visibly from the openings), a forged drum casing, and improved electrical reliability. During this upgrade phase the machines also lost their original natural metal livery and they received a less conspicuous tactical NATO-style grey/green paint scheme with metallic-grey undersides.
In this form the Ecuadorean Mystère IVEs soldiered on well into the Eighties, with a very good reliability record. During their active career they even saw “hot” action on several occasions, for instance in a continuous border dispute with Peru, the so-called Paquisha War. This brief military clash over the control of three watch posts flared up in January 1981 and the Mystères became involved. The first incident was a dogfight with an A-37B of the Fuerza Aérea del Peru (FAP), launched from Guayaquil to intercept it – with no casualities, though. Several similar interception incidents happened until early February 1981, and the FAE Mystères also flew several CAS missions to repel the Peruvian Jungle Infantry and to support Ecuadorian ground forces. Despite their age, the aircrafts’ ruggedness and simplicity proved them to be reliable, and its high roll rate and good handling at low altitude made it a versatile platform that was still competitive, even though its rather sluggish acceleration turned out to be a serious weak spot, esp. in the country’s typical mountainous terrain. Its relatively low range with internal fuel only was another operational problem.
The Mystère IVEs were finally retired in 1988 and replaced by Mirage F.1C fighters from France and IAI Kfir C.7 fighter bombers from Israel.
General characteristics:
Crew: 1
Length: 12.89 m (42 ft 3 in)
Wingspan: 11.12 m (36 ft 6 in)
Height: 4.6 m (15 ft 1 in)
Wing area: 32.06 m² (345.1 sq ft)
Empty weight: 5,860 kg (12,919 lb)
Gross weight: 8,510 kg (18,761 lb)
Max takeoff weight: 9,500 kg (20,944 lb)
Powerplant:
1× Rolls-Royce Tay 250 centrifugal-flow turbojet engine with 34.32 kN (7,720 lbf) thrust
Performance:
Maximum speed: 1,110 km/h (690 mph, 600 kn) at sea level
Range: 915 km (569 mi, 494 nmi) with internal fuel only
2,280 km (1,420 mi; 1,230 nmi) with drop tanks
Service ceiling: 15,000 m (49,000 ft)
Rate of climb: 40 m/s (7,900 ft/min)
Armament:
2× 30 mm (1.18 in) DEFA 553 cannon with 150 rounds per gun
1,000 kg (2,200 lb) of payload on four underwing hardpoints, incl. bombs, rockets or drop tanks
The kit and its assembly:
A very simple project, and basically just an OOB kit in the colors of a fictional operator. The whole thing was inspired by the question: what could have been a predecessor of the Ecuadorean Mirage F.1s? Not an existential question that might pop up frequently, but I quickly decided that the Mystère IV would have been a good/plausible contender. I found this idea even more attractive when I considered a camouflage paint scheme for it, because you only get either French or Indian machines in a uniform NMF outfit or IDF Mystères in desert camouflage (either in brown/blue or the later sand/earth/green scheme).
The kit is the venerable Matchbox Mystère IVA, even though in its Revell re-boxing. It’s a very simple affair, with partly crude details like the landing gear or the dreaded “trenches” for engraved surface details, esp. on the wings. But it goes together quite well, and with some corrections and additions you get a decent model.
The kit was basically built OOB, I just added underwings pylons with some ordnance for a fighter bomber mission: a pair of drop tanks and two SNEB missile launcher pods (tanks leftover from a Sword F-94, IIRC, and the pods from a Matchbox G.91Y). A complete tub with a floor and with side consoles (origin is uncertain, though – maybe it came from an Xtrakit Supermarin Swift?) was fitted to the cockpit and the primitive OOB ejection seat was replaced with something more convincing, pimped with seatbelts (masking tape) and ejection trigger handles (thin wire).
The flaps were lowered for a more natural look, and I added small oval boundary layer fences from a BAe Hawk as a personal twist. The clumsy front wheel, originally molded onto the strut as a single piece, was replaced with something better. The main landing gear covers were replaced with thinner styrene sheet material (the OOB parts are VERY thick) and pieces from hollow steel needles were implanted into the respective fairings as gun barrels.
A thinner pitot, created from heated sprue material, was used instead of the rather massive OOB part. The ranging radar fairing in the intake was slightly enlarged with the help of white glue. And, finally, a piece of sprue was implanted into the fin’s base as a brake parachute fairing, reminiscent of the Polish Lim-6/7, license-produced MiG-17s.
Painting and markings:
Actually quite conservative, with a typical Seventies paint scheme in dark grey/dark green. I even considered a more exotic three-tone scheme but found that – together with the colorful national markings – this would look too busy. Since there is no reference for a Mystère IV in such a guise, I simply adapted the standard pattern from a Royal Air Force Supermarine Swift. For a different look than the standard RAF colors – after all, the fictional Ecuadorean Mystère IVs were painted with domestic material. I used Humbrol 75 (Bronze Green) and ModelMaster 2057 (FS 36173, USAF Neutral Grey) for a good contrast between the upper tones, with Humbrol 56 (Alu Dope) underneath.
The tail section received a burned metal look, using Revell 91 (Iron) and some graphite. The cockpit interior was painted in a very dark grey (Revell 09, Anthracite) while the landing gear became silver-grey and the wells zinc-chromate primer (Humbrol 81). For some contrast, the drop tanks became shiny aluminum (Revell 99).
The kit received a light black ink washing, primarily for the recessed panel lines, and a subtle panel post-shading – for a less uniform surface than for true weathering, I’d imagine that the aircraft would be looked after well. However, some gun soot stains around the weapon ports were added with graphite, too.
The Ecuadorean roundels and unit markings came from an Xtradecal Strikemaster sheet, the tactical codes from a Croco Decal sheet for various South-American trainers. The flag on the rudder was, due to its sweep, painted, and most stencils were taken from the Mystère’s OOB sheet or procured from an Ecuadorian Mirage V on a Carpena sheet.
Finally, the kit was sealed with matt acrylic varnish, the ordnance was added and the position lights on the wing tips were created with silver and clear paint on top of that.
Well, this was not a spectacular conversion build, rather an OOB travesty with some cosmetic changes. However, the rather classic grey/green camouflage suits the tubby aircraft well and the bright national insignia really stand out on it – a pretty combo. The whole package as fictional Mystère IVE looks surprisingly convincing!
Greetings mate! As many of you know, I love marrying art, science, and math in my fine art portrait and landscape photography!
The 45surf and gold 45 revolver swimsuits, shirts, logos, designs, and lingerie are designed in accordance with the golden ratio! More about the design and my philosophy of "no retouching" on the beautiful goddesses in my new book:
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"Photographing Women Models: Portrait, Swimsuit, Lingerie, Boudoir, Fine Art, & Fashion Photography Exalting the Venus Goddess Archetype"
If you would like a free review copy, message me!
Epic Landscape Photography! New Book!
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And here's more on the golden ratio which appears in many of my landscape and portrait photographs (while shaping the proportions of the golden gun)!
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'
The dx4/dt=ic above the gun on the lingerie derives from my new physics books devoted to Light, Time, Dimension Theory!
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Thanks for being a fan! Would love to hears your thoughts on my philosophies and books! :)
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Beautiful swimsuit bikini model goddess!
Golden Ratio Lingerie Model Goddess LTD Theory Lingerie dx4/dt=ic! The Birth of Venus, Athena, and Artemis! Girls and Guns!
Would you like to see the whole set? Comment below and let me know!
Follow me!
I am working on several books on "epic photography," and I recently finished a related one titled: The Golden Number Ratio Principle: Why the Fibonacci Numbers Exalt Beauty and How to Create PHI Compositions in Art, Design, & Photography: An Artistic and Scientific Introduction to the Golden Mean . Message me on facebook for a free review copy!
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The Golden Ratio informs a lot of my art and photographic composition. The Golden Ratio also informs the design of the golden revolver on all the swimsuits and lingerie, as well as the 45surf logo! Not so long ago, I came up with the Golden Ratio Principle which describes why The Golden Ratio is so beautiful.
The Golden Number Ratio Principle: Dr. E’s Golden Ratio Principle: The golden ratio exalts beauty because the number is a characteristic of the mathematically and physically most efficient manners of growth and distribution, on both evolutionary and purely physical levels. The golden ratio ensures that the proportions and structure of that which came before provide the proportions and structure of that which comes after. Robust, ordered growth is naturally associated with health and beauty, and thus we evolved to perceive the golden ratio harmonies as inherently beautiful, as we saw and felt their presence in all vital growth and life—in the salient features and proportions of humans and nature alike, from the distribution of our facial features and bones to the arrangements of petals, leaves, and sunflowers seeds. As ratios between Fibonacci Numbers offer the closest whole-number approximations to the golden ratio, and as seeds, cells, leaves, bones, and other physical entities appear in whole numbers, the Fibonacci Numbers oft appear in nature’s elements as “growth’s numbers.” From the dawn of time, humanity sought to salute their gods in art and temples exalting the same proportion by which all their vital sustenance and they themselves had been created—the golden ratio.
The Birth of Venus! Beautiful Golden Ratio Swimsuit Bikini Model Goddess! Helen of Troy! She was tall, thin, fit, and quite pretty!
Read all about how classical art such as The Birth of Venus inspires all my photography!
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"Photographing Women Models: Portrait, Swimsuit, Lingerie, Boudoir, Fine Art, & Fashion Photography Exalting the Venus Goddess Archetype"
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based historical facts. BEWARE!
Some background:
The Hawker Cyclone was an evolutionary successor to the successful Hawker Typhoon and Tempest fighters and fighter-bombers of the Second World War. The Cyclone's design process was initiated in September 1942 by Sydney Camm, one of Hawker's foremost aircraft designers, to meet the Royal Air Force’s requirement for a lightweight Tempest Mk.II and V replacement.
The project, tentatively designated Tempest Mk. VIII, was formalised in January 1943 when the Air Ministry issued Specification F.2/42 around the "Tempest Light Fighter".This was followed up by Specification F.2/43, issued in May 1943, which required a high rate of climb of not less than 4,500 ft/min (23 m/s) from ground level to 20,000 feet (6,096 m), good fighting manoeu rability and a maximum speed of at least 450 mph (724 km/h) at 22,000 feet (6,705 m). The armament was to be four 20mm Hispano V cannon with a total capacity of 600 rounds, plus the capability of carrying two bombs each up to 1,000 pounds (454 kg). In April 1943, Hawker had also received Specification N.7/43 from the Admiralty, who sought a navalized version of the developing aircraft, what eventually led to the Hawker Sea Fury, which was a completely new aircraft, which only shared the general outlines of the Tempest.
The Royal Air Force was looking for a quicker solution, and Camm started working on a new laminar flow wing, which would further improve the Tempest’s speed. Further refinements were done to other aerodynamic components, too, like the radiator, since the Tempest V’s liquid-cooled Napier Sabre engine was to be used. After some experiments with new arrangements, an annular radiator directly behind the propeller was chosen – certainly inspired by fast German aircraft like the Fw 190D and developed by Napier.
A total of three prototypes were ordered; the first one was powered by a Napier Sabre IIA liquid-cooled H-24 sleeve-valve engine, generating 2,180 hp (1,625 kW), but the second and any following aircraft carried the more powerful Sabre V with 2,340 hp, driving a Rotol four-blade propeller. Later aircraft were even to carry the Napier Sabre VII, which was capable of developing 3,400–4,000 hp (2,535–2,983 kW) and pushing the top speed to 485 mph (780 km/h) and more. The third airframe was just a static test structure. However, since the differences between the Tempest and the new aircraft had become almost as big as to its predecessor, the Typhoon, the new type received its own name Cyclone.
The first Cyclone Mk. I to fly, on 30 August 1944, was NV950, and it became clear soon that the modifications would improve the Cyclone’s top speed vs. the Tempest by almost 30 mph (50 km/h), but the new components would also require a longer testing period than expected. The annular radiator frequently failed and overheated, and the new, slender wings caused directional stability problems so that the complete tail section had to be re-designed. This troubling phase took more than 6 months, so that eventual service aircraft would only be ready in mid-1945 – too late for any serious impact in the conflict.
However, since the Hawker Fury, the land-based variant of the Sea Fury, which had been developed from the Tempest for the Royal Navy in parallel, had been cancelled, the Royal Air Force still ordered 150 Cyclone fighters (F Mk. I), of which one third would also carry cameras and other reconnaissance equipment (as Cyclone FR Mk.II). Due to the end of hostilities in late 1945, this order immediately lost priority. Consequently, the first production Cyclone fighters were delivered in summer 1946 – and in the meantime, jet fighters had rendered the piston-powered fighters obsolete, at least in RAF service. As a consequence, all Cyclones were handed over to friendly Commonwealth nations and their nascent air forces, e. g. India, Thailand or Burma. India received its first Cyclones in late 1947, just when the Kashmir conflict with Pakistan entered a hot phase. The machines became quickly involved in this conflict from early 1948 onwards.
Cyclones played an important role in the strikes against hostiles at Pir Badesar and the dominating Pir Kalewa. The taking of Ramgarh fort and Pt. 6944 on the west flank of Bhimbar Gali was to be a classic close support action with Indian forces carrying out a final bayonet charge against the enemy trenches whilst RIAF Cyclones and Tempests strafed and rocketed the trenches at close quarters. On a chance reconnaissance, enemy airfields were located at Gilgit and 40 NMs south, at Chilas. Cyclones flew several strikes against the landing strips in Oct and Nov 48, cratering & damaging both and destroying several hangars, barracks and radio installations. This attack destroyed Pakistani plans to build an offensive air capability in the North. Already, with Tempests and Cyclones prowling the valleys, Pakistani re-supply by Dakotas had been limited to hazardous night flying through the valleys.
After the end of hostilities in late 1948 and the ensuing independence, the Cyclone squadrons settled into their peace time stations. However, constant engine troubles (particularly the radiator) continued to claim aircraft and lives and the skill required to land the Cyclone because of its high approach speed continued to cause several write offs. The arrival of the jet-engined Vampire were the first signs of the Cyclone’s demise. As the IAF began a rapid expansion to an all jet force, several Tempest and Cyclone squadrons began converting to Vampires, 7 Squadron being the first in Dec 49. By this time it had already been decided that the piston-engine fighters would be relegated to the fighter lead-in role to train pilots for the new jet fighters. A conversion training flight was set up at Ambala in Sep 49 with Spitfire T Mk IXs, XVIIIs and Tempests to provide 16 hrs/six weeks of supervised Tempest training. This unit eventually moved to Hakimpet two years later and operated till the end of 1952. Some Cyclone FR Mk. IIs remained in front line service until 1954, though.
General characteristics:
Crew: One
Length: 35 ft 5 3/4 in (10.83 m)
Wingspan: 42 ft 5 1/2 in (12.96 m)
Height (tail down): 15 ft 6 3/4 in (4.75 m)
Wing area: 302 ft² (28 m²)
Empty weight: 9,250 lb (4,195 kg)
Loaded weight: 11,400 lb (5,176 kg)
Max. takeoff weight: 13,640 lb (6,190 kg)
Powerplant:
1× Napier Sabre V liquid-cooled H-24 sleeve-valve engine with 2,340 hp (1,683 kW)
Performance:
Maximum speed: 460 mph (740 km/h) 18,400 ft (5,608 m),
Range: 740 mi (1,190 km)
1,530 mi (2,462 km) with two 90 gal (409 l) drop tanks
Service ceiling: 36,500 ft (11,125 m)
Rate of climb: 4,700 ft/min (23.9 m/s)
Wing loading: 37.75 lb/ft² (184.86 kg/m²)
Power/mass: 0.21 hp/lb (0.31 kW/kg)
Armament:
4× 20 mm (.79 in) Mark V Hispano cannons, 200 RPG
2× underwing hardpoints for 500 lb (227 kg) or 1,000 lb (454 kg) bombs
or 2 × 45 gal (205 l) or 2 × 90 gal (409 l) drop tanks
plus 6× 3” (76.2 mm) RP-3 rockets
The kit and its assembly:
Another episode in the series “Things to make and do with Supermarine Attacker wings”. And what started as a simple switch of wings eventually turned into a major kitbashing, since the model evolved from a modded Tempest into something more complex and conclusive.
The initial spark was the idea of a Hawker alternative to Supermarine’s Spiteful and Seafang developments – especially with their slender laminar flow wings. Wouldn’t a Hawker alternative make sense?
Said and done, I dug out a NOVO Attacker kit and a Matchbox Tempest, and started measuring – and the wing transplantation appeared feasible! I made the cut on the Tempest wing just outside of the oil cooler, and the Attacker wings were then attached to these stubs – after some gaps for the landing gear wells had been cut into the massive lower wing halves. The stunt went more smoothly than expected, the only cosmetic flaw is that the guns went pretty far outboard, but that’s negligible.
But the different wings were not enough. I had recently seen in a book a picture of a Tempest (NV 768) with an experimental annular radiator for the Sabre engine (looking like a streamlined Tempest II), and wondered if this arrangement would have been the aerodynamically more efficient solution than the bulbous chin radiator of the Tempest V and VI? I decided to integrate this feature into my build, too, even though not as a copy of the real-world arrangement. The whole nose section, even though based on the OOB Mk. V nose, was scratched and re-sculpted with lots of putty. The radiator intake comes from a FROG He 219, with the front end opened and a fan from a Matchbox Fw 190 placed inside, as well as a styrene tube for the new propeller. The latter was scratched, too, from a Matchbox He 70 spinner and single blades from an Italeri F4U, plus a metal axis. The exhaust stubs were taken OOB, but their attachment slits had to be re-engraved into the new and almost massive nose section.
Once the wings and the nose became more concrete, I found that the Tempest’s original rounded tail surfaces would not match with the new, square wings. Therefore I replaced the stabilizers with donations from a Heller F-84G and modified the fin with a new, square tip (from an Intech Fw 190D) and got rid of the fin fillet – both just small modifications, but they change the Tempest’s profile thoroughly.
In order to underline the aircraft’s new, sleek lines, I left away any ordnance – but instead I added some camera fairings: one under the rear fuselage or a pair of vertical/oblique cameras, and another camera window portside for a horizontal camera. The openings were drilled, and, after painting, the kit the camera windows were created with Humbrol Clearfix.
Painting and markings:
Somehow I thought that this aircraft had to carry Indian markings – and I had a set of standard Chakra Wheels from the late Forties period in my stash. The camouflage is, typical for early IAF machines of British origin, RAF standard, with Dark Green and Ocean Grey from above and Medium Sea Grey from below. I just used the more brownish pst-war RAF Dark Green tone (Humbrol 163), coupled with the rather light Ocean Grey from Modelmaster (2057). The underside became Humbrol 165. All interior surfaces were painted with RAF Interior Green, nothing fancy. The only colorful addition is the saffron-colored spinner, in an attempt to match the fin flash’s tone.
As a standard measure, the kit received a black ink wash and some panel post-shading with lighter tones – only subtly, since the machine was not to look too weathered and beaten, just used from its Kashmir involvements.
The national markings come from a Printscale Airspeed Oxford sheet, the tactical code with alternating white and black letters, depending on the underground (the sky fuselage band comes from a Matchbox Brewster Buffalo), was puzzled together from single letters from TL Modellbau – both seen on different contemporary RIAF aircraft.
As another, small individual detail I gave the machine a tactical code letter on the fuselage, and the small tiger emblems under the cockpit were home-printed from the official IAF No. 1 Squadron badge.
Despite the massive modifications this one is a relatively subtle result, all the changes become only visible at a second glance. A sleek aircraft, and from certain angley the Cyclone looks like an A-1 Skyraider on a diet?
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
Some background:
When Marcel Dassault started work on jet-powered fighters after WWII, the development evolved in gradual steps instead of quantum leaps, leading to a long line of aircraft. The Mystère IV was an evolutionary development of the Mystère II aircraft. Although bearing an external resemblance to the earlier aircraft, the Mystère IV was in fact a new design with aerodynamic improvements for supersonic flight. The prototype first flew on 28 September 1952, and the aircraft entered service in April 1953. The first 50 Mystere IVA production aircraft were powered by British Rolls-Royce Tay turbojets, while the remainder had the French-built Hispano-Suiza Verdon 350 version of that engine.
France was the main operator of the Mystère IV. In April 1953 the United States government and the United States Air Force placed an order for 223 aircraft to be operated by the French, and at the peak usage the Armée de l‘air operated 6 squadrons. Most of the aircraft were purchased under a United States Offshore Procurement contract and many were returned to US custody after they were retired. The Mystère IVs were used in the 1956 Suez Crisis and continued to remain in French service into the 1980s, even though they were quickly relegated into second line duties as more capable types like the Super Mystère SM2B or the Mirage III entered service.
Other international operators included Israel (using about sixty Mystère IVs in large-scale combat during the 1967 Six Day War), India (104 aircraft procured in 1957 and extensively used in the Indo-Pakistani War of 1965) and Ecuador.
The Fuerza Aérea Ecuatoriana (FAE, Ecuadorian Air Force) was officially created on October 27, 1920. However, like in many other countries, military flying activity already started before the formal date of birth of the Air Force. By 1939 the Ecuadorian Air Force was still limited to about 30 aircraft, though, and a staff of about 60, including 10 officers. Military aviation did not start in earnest until the early forties when an Ecuadorian mission to the United States resulted in the delivery of an assortment of aircraft for the Aviation school at Salinas: three Ryan PT-22 Recruits, six Curtiss-Wright CW-22 Falcons, six Fairchild PT-19A Cornells and three North American AT-6A Harvards arrived in March 1942, considerably boosting the capacity of the Escuela de Aviación at Salinas.
The 1950s and 1960s saw a further necessary buildup of the air force, gaining more units and aircraft, while efforts were made in enhancing the facilities at various airbases. In May 1961 the "First Air Zone" with its subordinate unit Ala de Transportes No.11 was founded. The "Second Air Zone" controlled the units in the southern half of Ecuador, Ala de Combate No.21 at Taura, Ala de Rescate No.22 at Guayaquil and Ala de Combate No.23 at Manta as well as the Escuela Superior Militar de Aviación "Cosme Rennella B." (ESMA) at Salinas.
It was at this time that the FAE was looking for a capable (yet affordable) jet fighter that would replace the vintage F-47 “Thunderbolt” piston engine fighters of American origin that had been operated since 1947 as well as the ageing fleet of Gloster Meteor jet fighters. After consulting various options, including the British Hawker Hunter and the American F-86 Sabre, Ecuador settled upon the French Mystère IV. A total of 32 aircraft were ordered in 1958 and delivered until early 1963 in two tranches, subsequently outfitting two combat squadrons.
The Ecuadorian aircraft resembled the early French Mystère IV standard and were powered by the British Rolls-Royce Tay 250. However, they differed in small details and incorporated some updates, leading to the individual designation Mystère IVE (for Ecuador). This included a modified instrumentation and a British Martin Baker ejection seat in the cockpit. On the outside, a fairing for a brake parachute at the fin’s base was the most obvious change, and there were small oval boundary layer fences on the wings’ leading edges that improved the aircraft’s handling. The front landing gear was slightly different, too, now outfitted with a mudguard.
To improve the aircraft’s capabilities in air-to-air combat, an American AN/APG-30 range-finding radar was fitted, mounted to the center of the air intake (under a slightly enlarged radome) and linked with the gyroscopic gunsight in the cockpit. It was effective at a range of up to 2.750 m, but only covered a narrow cone directly in front of the aircraft. Initially the aircraft were operated as pure fighters/interceptors, but soon they also took over ground attack and CAS missions with iron bombs and unguided missiles, even though the Mystère IV’s ordnance capacity was rather limited. But the aircraft had a good handling at low altitude and were a stable weapon platform, so that the pilots operated them with confidence.
In the early Seventies, Ecuador had plans to upgrade its Mystères with Pratt & Whitney J48-P-5 engines, a license-built version of the Rolls-Royce Tay from the USA and outfitted with an afterburner. With reheat the J48 delivered 8,750 lbf (38.9 kN) of thrust, but continuous dry thrust was only 6,350 lbf (28.2 kN), markedly less than the old Tay engine. The high fuel consumption with operating afterburner would have markedly limited the aircraft’s range, and this engine switch would have necessitated major modifications to the aircrafts’ tail section, so that the upgrade eventually did not come to fruition due the lack of funds and the rather limited and only temporary improvement in performance.
Nevertheless, in course of their career in Ecuador, the Mystères’ still underwent some modifications and modernizations. In the early Seventies an MLU program was carried out: the retractable pannier for unguided missiles was deleted in favor of an extra fuel tank and upgraded navigational and weapon avionics. The latter included wirings for IR-guided AIM-9B Sidewinder AAMs on the outer underwing pylons, what greatly improved the aircraft’s air-to-air capabilities. The original DEFA 552 guns were replaced with more modern DEFA 553s, which had a new feed system, a nitro-chrome plated steel barrel (which was longer than the 552’s and now protruded visibly from the openings), a forged drum casing, and improved electrical reliability. During this upgrade phase the machines also lost their original natural metal livery and they received a less conspicuous tactical NATO-style grey/green paint scheme with metallic-grey undersides.
In this form the Ecuadorean Mystère IVEs soldiered on well into the Eighties, with a very good reliability record. During their active career they even saw “hot” action on several occasions, for instance in a continuous border dispute with Peru, the so-called Paquisha War. This brief military clash over the control of three watch posts flared up in January 1981 and the Mystères became involved. The first incident was a dogfight with an A-37B of the Fuerza Aérea del Peru (FAP), launched from Guayaquil to intercept it – with no casualities, though. Several similar interception incidents happened until early February 1981, and the FAE Mystères also flew several CAS missions to repel the Peruvian Jungle Infantry and to support Ecuadorian ground forces. Despite their age, the aircrafts’ ruggedness and simplicity proved them to be reliable, and its high roll rate and good handling at low altitude made it a versatile platform that was still competitive, even though its rather sluggish acceleration turned out to be a serious weak spot, esp. in the country’s typical mountainous terrain. Its relatively low range with internal fuel only was another operational problem.
The Mystère IVEs were finally retired in 1988 and replaced by Mirage F.1C fighters from France and IAI Kfir C.7 fighter bombers from Israel.
General characteristics:
Crew: 1
Length: 12.89 m (42 ft 3 in)
Wingspan: 11.12 m (36 ft 6 in)
Height: 4.6 m (15 ft 1 in)
Wing area: 32.06 m² (345.1 sq ft)
Empty weight: 5,860 kg (12,919 lb)
Gross weight: 8,510 kg (18,761 lb)
Max takeoff weight: 9,500 kg (20,944 lb)
Powerplant:
1× Rolls-Royce Tay 250 centrifugal-flow turbojet engine with 34.32 kN (7,720 lbf) thrust
Performance:
Maximum speed: 1,110 km/h (690 mph, 600 kn) at sea level
Range: 915 km (569 mi, 494 nmi) with internal fuel only
2,280 km (1,420 mi; 1,230 nmi) with drop tanks
Service ceiling: 15,000 m (49,000 ft)
Rate of climb: 40 m/s (7,900 ft/min)
Armament:
2× 30 mm (1.18 in) DEFA 553 cannon with 150 rounds per gun
1,000 kg (2,200 lb) of payload on four underwing hardpoints, incl. bombs, rockets or drop tanks
The kit and its assembly:
A very simple project, and basically just an OOB kit in the colors of a fictional operator. The whole thing was inspired by the question: what could have been a predecessor of the Ecuadorean Mirage F.1s? Not an existential question that might pop up frequently, but I quickly decided that the Mystère IV would have been a good/plausible contender. I found this idea even more attractive when I considered a camouflage paint scheme for it, because you only get either French or Indian machines in a uniform NMF outfit or IDF Mystères in desert camouflage (either in brown/blue or the later sand/earth/green scheme).
The kit is the venerable Matchbox Mystère IVA, even though in its Revell re-boxing. It’s a very simple affair, with partly crude details like the landing gear or the dreaded “trenches” for engraved surface details, esp. on the wings. But it goes together quite well, and with some corrections and additions you get a decent model.
The kit was basically built OOB, I just added underwings pylons with some ordnance for a fighter bomber mission: a pair of drop tanks and two SNEB missile launcher pods (tanks leftover from a Sword F-94, IIRC, and the pods from a Matchbox G.91Y). A complete tub with a floor and with side consoles (origin is uncertain, though – maybe it came from an Xtrakit Supermarin Swift?) was fitted to the cockpit and the primitive OOB ejection seat was replaced with something more convincing, pimped with seatbelts (masking tape) and ejection trigger handles (thin wire).
The flaps were lowered for a more natural look, and I added small oval boundary layer fences from a BAe Hawk as a personal twist. The clumsy front wheel, originally molded onto the strut as a single piece, was replaced with something better. The main landing gear covers were replaced with thinner styrene sheet material (the OOB parts are VERY thick) and pieces from hollow steel needles were implanted into the respective fairings as gun barrels.
A thinner pitot, created from heated sprue material, was used instead of the rather massive OOB part. The ranging radar fairing in the intake was slightly enlarged with the help of white glue. And, finally, a piece of sprue was implanted into the fin’s base as a brake parachute fairing, reminiscent of the Polish Lim-6/7, license-produced MiG-17s.
Painting and markings:
Actually quite conservative, with a typical Seventies paint scheme in dark grey/dark green. I even considered a more exotic three-tone scheme but found that – together with the colorful national markings – this would look too busy. Since there is no reference for a Mystère IV in such a guise, I simply adapted the standard pattern from a Royal Air Force Supermarine Swift. For a different look than the standard RAF colors – after all, the fictional Ecuadorean Mystère IVs were painted with domestic material. I used Humbrol 75 (Bronze Green) and ModelMaster 2057 (FS 36173, USAF Neutral Grey) for a good contrast between the upper tones, with Humbrol 56 (Alu Dope) underneath.
The tail section received a burned metal look, using Revell 91 (Iron) and some graphite. The cockpit interior was painted in a very dark grey (Revell 09, Anthracite) while the landing gear became silver-grey and the wells zinc-chromate primer (Humbrol 81). For some contrast, the drop tanks became shiny aluminum (Revell 99).
The kit received a light black ink washing, primarily for the recessed panel lines, and a subtle panel post-shading – for a less uniform surface than for true weathering, I’d imagine that the aircraft would be looked after well. However, some gun soot stains around the weapon ports were added with graphite, too.
The Ecuadorean roundels and unit markings came from an Xtradecal Strikemaster sheet, the tactical codes from a Croco Decal sheet for various South-American trainers. The flag on the rudder was, due to its sweep, painted, and most stencils were taken from the Mystère’s OOB sheet or procured from an Ecuadorian Mirage V on a Carpena sheet.
Finally, the kit was sealed with matt acrylic varnish, the ordnance was added and the position lights on the wing tips were created with silver and clear paint on top of that.
Well, this was not a spectacular conversion build, rather an OOB travesty with some cosmetic changes. However, the rather classic grey/green camouflage suits the tubby aircraft well and the bright national insignia really stand out on it – a pretty combo. The whole package as fictional Mystère IVE looks surprisingly convincing!
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
Some background:
When Marcel Dassault started work on jet-powered fighters after WWII, the development evolved in gradual steps instead of quantum leaps, leading to a long line of aircraft. The Mystère IV was an evolutionary development of the Mystère II aircraft. Although bearing an external resemblance to the earlier aircraft, the Mystère IV was in fact a new design with aerodynamic improvements for supersonic flight. The prototype first flew on 28 September 1952, and the aircraft entered service in April 1953. The first 50 Mystere IVA production aircraft were powered by British Rolls-Royce Tay turbojets, while the remainder had the French-built Hispano-Suiza Verdon 350 version of that engine.
France was the main operator of the Mystère IV. In April 1953 the United States government and the United States Air Force placed an order for 223 aircraft to be operated by the French, and at the peak usage the Armée de l‘air operated 6 squadrons. Most of the aircraft were purchased under a United States Offshore Procurement contract and many were returned to US custody after they were retired. The Mystère IVs were used in the 1956 Suez Crisis and continued to remain in French service into the 1980s, even though they were quickly relegated into second line duties as more capable types like the Super Mystère SM2B or the Mirage III entered service.
Other international operators included Israel (using about sixty Mystère IVs in large-scale combat during the 1967 Six Day War), India (104 aircraft procured in 1957 and extensively used in the Indo-Pakistani War of 1965) and Ecuador.
The Fuerza Aérea Ecuatoriana (FAE, Ecuadorian Air Force) was officially created on October 27, 1920. However, like in many other countries, military flying activity already started before the formal date of birth of the Air Force. By 1939 the Ecuadorian Air Force was still limited to about 30 aircraft, though, and a staff of about 60, including 10 officers. Military aviation did not start in earnest until the early forties when an Ecuadorian mission to the United States resulted in the delivery of an assortment of aircraft for the Aviation school at Salinas: three Ryan PT-22 Recruits, six Curtiss-Wright CW-22 Falcons, six Fairchild PT-19A Cornells and three North American AT-6A Harvards arrived in March 1942, considerably boosting the capacity of the Escuela de Aviación at Salinas.
The 1950s and 1960s saw a further necessary buildup of the air force, gaining more units and aircraft, while efforts were made in enhancing the facilities at various airbases. In May 1961 the "First Air Zone" with its subordinate unit Ala de Transportes No.11 was founded. The "Second Air Zone" controlled the units in the southern half of Ecuador, Ala de Combate No.21 at Taura, Ala de Rescate No.22 at Guayaquil and Ala de Combate No.23 at Manta as well as the Escuela Superior Militar de Aviación "Cosme Rennella B." (ESMA) at Salinas.
It was at this time that the FAE was looking for a capable (yet affordable) jet fighter that would replace the vintage F-47 “Thunderbolt” piston engine fighters of American origin that had been operated since 1947 as well as the ageing fleet of Gloster Meteor jet fighters. After consulting various options, including the British Hawker Hunter and the American F-86 Sabre, Ecuador settled upon the French Mystère IV. A total of 32 aircraft were ordered in 1958 and delivered until early 1963 in two tranches, subsequently outfitting two combat squadrons.
The Ecuadorian aircraft resembled the early French Mystère IV standard and were powered by the British Rolls-Royce Tay 250. However, they differed in small details and incorporated some updates, leading to the individual designation Mystère IVE (for Ecuador). This included a modified instrumentation and a British Martin Baker ejection seat in the cockpit. On the outside, a fairing for a brake parachute at the fin’s base was the most obvious change, and there were small oval boundary layer fences on the wings’ leading edges that improved the aircraft’s handling. The front landing gear was slightly different, too, now outfitted with a mudguard.
To improve the aircraft’s capabilities in air-to-air combat, an American AN/APG-30 range-finding radar was fitted, mounted to the center of the air intake (under a slightly enlarged radome) and linked with the gyroscopic gunsight in the cockpit. It was effective at a range of up to 2.750 m, but only covered a narrow cone directly in front of the aircraft. Initially the aircraft were operated as pure fighters/interceptors, but soon they also took over ground attack and CAS missions with iron bombs and unguided missiles, even though the Mystère IV’s ordnance capacity was rather limited. But the aircraft had a good handling at low altitude and were a stable weapon platform, so that the pilots operated them with confidence.
In the early Seventies, Ecuador had plans to upgrade its Mystères with Pratt & Whitney J48-P-5 engines, a license-built version of the Rolls-Royce Tay from the USA and outfitted with an afterburner. With reheat the J48 delivered 8,750 lbf (38.9 kN) of thrust, but continuous dry thrust was only 6,350 lbf (28.2 kN), markedly less than the old Tay engine. The high fuel consumption with operating afterburner would have markedly limited the aircraft’s range, and this engine switch would have necessitated major modifications to the aircrafts’ tail section, so that the upgrade eventually did not come to fruition due the lack of funds and the rather limited and only temporary improvement in performance.
Nevertheless, in course of their career in Ecuador, the Mystères’ still underwent some modifications and modernizations. In the early Seventies an MLU program was carried out: the retractable pannier for unguided missiles was deleted in favor of an extra fuel tank and upgraded navigational and weapon avionics. The latter included wirings for IR-guided AIM-9B Sidewinder AAMs on the outer underwing pylons, what greatly improved the aircraft’s air-to-air capabilities. The original DEFA 552 guns were replaced with more modern DEFA 553s, which had a new feed system, a nitro-chrome plated steel barrel (which was longer than the 552’s and now protruded visibly from the openings), a forged drum casing, and improved electrical reliability. During this upgrade phase the machines also lost their original natural metal livery and they received a less conspicuous tactical NATO-style grey/green paint scheme with metallic-grey undersides.
In this form the Ecuadorean Mystère IVEs soldiered on well into the Eighties, with a very good reliability record. During their active career they even saw “hot” action on several occasions, for instance in a continuous border dispute with Peru, the so-called Paquisha War. This brief military clash over the control of three watch posts flared up in January 1981 and the Mystères became involved. The first incident was a dogfight with an A-37B of the Fuerza Aérea del Peru (FAP), launched from Guayaquil to intercept it – with no casualities, though. Several similar interception incidents happened until early February 1981, and the FAE Mystères also flew several CAS missions to repel the Peruvian Jungle Infantry and to support Ecuadorian ground forces. Despite their age, the aircrafts’ ruggedness and simplicity proved them to be reliable, and its high roll rate and good handling at low altitude made it a versatile platform that was still competitive, even though its rather sluggish acceleration turned out to be a serious weak spot, esp. in the country’s typical mountainous terrain. Its relatively low range with internal fuel only was another operational problem.
The Mystère IVEs were finally retired in 1988 and replaced by Mirage F.1C fighters from France and IAI Kfir C.7 fighter bombers from Israel.
General characteristics:
Crew: 1
Length: 12.89 m (42 ft 3 in)
Wingspan: 11.12 m (36 ft 6 in)
Height: 4.6 m (15 ft 1 in)
Wing area: 32.06 m² (345.1 sq ft)
Empty weight: 5,860 kg (12,919 lb)
Gross weight: 8,510 kg (18,761 lb)
Max takeoff weight: 9,500 kg (20,944 lb)
Powerplant:
1× Rolls-Royce Tay 250 centrifugal-flow turbojet engine with 34.32 kN (7,720 lbf) thrust
Performance:
Maximum speed: 1,110 km/h (690 mph, 600 kn) at sea level
Range: 915 km (569 mi, 494 nmi) with internal fuel only
2,280 km (1,420 mi; 1,230 nmi) with drop tanks
Service ceiling: 15,000 m (49,000 ft)
Rate of climb: 40 m/s (7,900 ft/min)
Armament:
2× 30 mm (1.18 in) DEFA 553 cannon with 150 rounds per gun
1,000 kg (2,200 lb) of payload on four underwing hardpoints, incl. bombs, rockets or drop tanks
The kit and its assembly:
A very simple project, and basically just an OOB kit in the colors of a fictional operator. The whole thing was inspired by the question: what could have been a predecessor of the Ecuadorean Mirage F.1s? Not an existential question that might pop up frequently, but I quickly decided that the Mystère IV would have been a good/plausible contender. I found this idea even more attractive when I considered a camouflage paint scheme for it, because you only get either French or Indian machines in a uniform NMF outfit or IDF Mystères in desert camouflage (either in brown/blue or the later sand/earth/green scheme).
The kit is the venerable Matchbox Mystère IVA, even though in its Revell re-boxing. It’s a very simple affair, with partly crude details like the landing gear or the dreaded “trenches” for engraved surface details, esp. on the wings. But it goes together quite well, and with some corrections and additions you get a decent model.
The kit was basically built OOB, I just added underwings pylons with some ordnance for a fighter bomber mission: a pair of drop tanks and two SNEB missile launcher pods (tanks leftover from a Sword F-94, IIRC, and the pods from a Matchbox G.91Y). A complete tub with a floor and with side consoles (origin is uncertain, though – maybe it came from an Xtrakit Supermarin Swift?) was fitted to the cockpit and the primitive OOB ejection seat was replaced with something more convincing, pimped with seatbelts (masking tape) and ejection trigger handles (thin wire).
The flaps were lowered for a more natural look, and I added small oval boundary layer fences from a BAe Hawk as a personal twist. The clumsy front wheel, originally molded onto the strut as a single piece, was replaced with something better. The main landing gear covers were replaced with thinner styrene sheet material (the OOB parts are VERY thick) and pieces from hollow steel needles were implanted into the respective fairings as gun barrels.
A thinner pitot, created from heated sprue material, was used instead of the rather massive OOB part. The ranging radar fairing in the intake was slightly enlarged with the help of white glue. And, finally, a piece of sprue was implanted into the fin’s base as a brake parachute fairing, reminiscent of the Polish Lim-6/7, license-produced MiG-17s.
Painting and markings:
Actually quite conservative, with a typical Seventies paint scheme in dark grey/dark green. I even considered a more exotic three-tone scheme but found that – together with the colorful national markings – this would look too busy. Since there is no reference for a Mystère IV in such a guise, I simply adapted the standard pattern from a Royal Air Force Supermarine Swift. For a different look than the standard RAF colors – after all, the fictional Ecuadorean Mystère IVs were painted with domestic material. I used Humbrol 75 (Bronze Green) and ModelMaster 2057 (FS 36173, USAF Neutral Grey) for a good contrast between the upper tones, with Humbrol 56 (Alu Dope) underneath.
The tail section received a burned metal look, using Revell 91 (Iron) and some graphite. The cockpit interior was painted in a very dark grey (Revell 09, Anthracite) while the landing gear became silver-grey and the wells zinc-chromate primer (Humbrol 81). For some contrast, the drop tanks became shiny aluminum (Revell 99).
The kit received a light black ink washing, primarily for the recessed panel lines, and a subtle panel post-shading – for a less uniform surface than for true weathering, I’d imagine that the aircraft would be looked after well. However, some gun soot stains around the weapon ports were added with graphite, too.
The Ecuadorean roundels and unit markings came from an Xtradecal Strikemaster sheet, the tactical codes from a Croco Decal sheet for various South-American trainers. The flag on the rudder was, due to its sweep, painted, and most stencils were taken from the Mystère’s OOB sheet or procured from an Ecuadorian Mirage V on a Carpena sheet.
Finally, the kit was sealed with matt acrylic varnish, the ordnance was added and the position lights on the wing tips were created with silver and clear paint on top of that.
Well, this was not a spectacular conversion build, rather an OOB travesty with some cosmetic changes. However, the rather classic grey/green camouflage suits the tubby aircraft well and the bright national insignia really stand out on it – a pretty combo. The whole package as fictional Mystère IVE looks surprisingly convincing!
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
Some background:
When Marcel Dassault started work on jet-powered fighters after WWII, the development evolved in gradual steps instead of quantum leaps, leading to a long line of aircraft. The Mystère IV was an evolutionary development of the Mystère II aircraft. Although bearing an external resemblance to the earlier aircraft, the Mystère IV was in fact a new design with aerodynamic improvements for supersonic flight. The prototype first flew on 28 September 1952, and the aircraft entered service in April 1953. The first 50 Mystere IVA production aircraft were powered by British Rolls-Royce Tay turbojets, while the remainder had the French-built Hispano-Suiza Verdon 350 version of that engine.
France was the main operator of the Mystère IV. In April 1953 the United States government and the United States Air Force placed an order for 223 aircraft to be operated by the French, and at the peak usage the Armée de l‘air operated 6 squadrons. Most of the aircraft were purchased under a United States Offshore Procurement contract and many were returned to US custody after they were retired. The Mystère IVs were used in the 1956 Suez Crisis and continued to remain in French service into the 1980s, even though they were quickly relegated into second line duties as more capable types like the Super Mystère SM2B or the Mirage III entered service.
Other international operators included Israel (using about sixty Mystère IVs in large-scale combat during the 1967 Six Day War), India (104 aircraft procured in 1957 and extensively used in the Indo-Pakistani War of 1965) and Ecuador.
The Fuerza Aérea Ecuatoriana (FAE, Ecuadorian Air Force) was officially created on October 27, 1920. However, like in many other countries, military flying activity already started before the formal date of birth of the Air Force. By 1939 the Ecuadorian Air Force was still limited to about 30 aircraft, though, and a staff of about 60, including 10 officers. Military aviation did not start in earnest until the early forties when an Ecuadorian mission to the United States resulted in the delivery of an assortment of aircraft for the Aviation school at Salinas: three Ryan PT-22 Recruits, six Curtiss-Wright CW-22 Falcons, six Fairchild PT-19A Cornells and three North American AT-6A Harvards arrived in March 1942, considerably boosting the capacity of the Escuela de Aviación at Salinas.
The 1950s and 1960s saw a further necessary buildup of the air force, gaining more units and aircraft, while efforts were made in enhancing the facilities at various airbases. In May 1961 the "First Air Zone" with its subordinate unit Ala de Transportes No.11 was founded. The "Second Air Zone" controlled the units in the southern half of Ecuador, Ala de Combate No.21 at Taura, Ala de Rescate No.22 at Guayaquil and Ala de Combate No.23 at Manta as well as the Escuela Superior Militar de Aviación "Cosme Rennella B." (ESMA) at Salinas.
It was at this time that the FAE was looking for a capable (yet affordable) jet fighter that would replace the vintage F-47 “Thunderbolt” piston engine fighters of American origin that had been operated since 1947 as well as the ageing fleet of Gloster Meteor jet fighters. After consulting various options, including the British Hawker Hunter and the American F-86 Sabre, Ecuador settled upon the French Mystère IV. A total of 32 aircraft were ordered in 1958 and delivered until early 1963 in two tranches, subsequently outfitting two combat squadrons.
The Ecuadorian aircraft resembled the early French Mystère IV standard and were powered by the British Rolls-Royce Tay 250. However, they differed in small details and incorporated some updates, leading to the individual designation Mystère IVE (for Ecuador). This included a modified instrumentation and a British Martin Baker ejection seat in the cockpit. On the outside, a fairing for a brake parachute at the fin’s base was the most obvious change, and there were small oval boundary layer fences on the wings’ leading edges that improved the aircraft’s handling. The front landing gear was slightly different, too, now outfitted with a mudguard.
To improve the aircraft’s capabilities in air-to-air combat, an American AN/APG-30 range-finding radar was fitted, mounted to the center of the air intake (under a slightly enlarged radome) and linked with the gyroscopic gunsight in the cockpit. It was effective at a range of up to 2.750 m, but only covered a narrow cone directly in front of the aircraft. Initially the aircraft were operated as pure fighters/interceptors, but soon they also took over ground attack and CAS missions with iron bombs and unguided missiles, even though the Mystère IV’s ordnance capacity was rather limited. But the aircraft had a good handling at low altitude and were a stable weapon platform, so that the pilots operated them with confidence.
In the early Seventies, Ecuador had plans to upgrade its Mystères with Pratt & Whitney J48-P-5 engines, a license-built version of the Rolls-Royce Tay from the USA and outfitted with an afterburner. With reheat the J48 delivered 8,750 lbf (38.9 kN) of thrust, but continuous dry thrust was only 6,350 lbf (28.2 kN), markedly less than the old Tay engine. The high fuel consumption with operating afterburner would have markedly limited the aircraft’s range, and this engine switch would have necessitated major modifications to the aircrafts’ tail section, so that the upgrade eventually did not come to fruition due the lack of funds and the rather limited and only temporary improvement in performance.
Nevertheless, in course of their career in Ecuador, the Mystères’ still underwent some modifications and modernizations. In the early Seventies an MLU program was carried out: the retractable pannier for unguided missiles was deleted in favor of an extra fuel tank and upgraded navigational and weapon avionics. The latter included wirings for IR-guided AIM-9B Sidewinder AAMs on the outer underwing pylons, what greatly improved the aircraft’s air-to-air capabilities. The original DEFA 552 guns were replaced with more modern DEFA 553s, which had a new feed system, a nitro-chrome plated steel barrel (which was longer than the 552’s and now protruded visibly from the openings), a forged drum casing, and improved electrical reliability. During this upgrade phase the machines also lost their original natural metal livery and they received a less conspicuous tactical NATO-style grey/green paint scheme with metallic-grey undersides.
In this form the Ecuadorean Mystère IVEs soldiered on well into the Eighties, with a very good reliability record. During their active career they even saw “hot” action on several occasions, for instance in a continuous border dispute with Peru, the so-called Paquisha War. This brief military clash over the control of three watch posts flared up in January 1981 and the Mystères became involved. The first incident was a dogfight with an A-37B of the Fuerza Aérea del Peru (FAP), launched from Guayaquil to intercept it – with no casualities, though. Several similar interception incidents happened until early February 1981, and the FAE Mystères also flew several CAS missions to repel the Peruvian Jungle Infantry and to support Ecuadorian ground forces. Despite their age, the aircrafts’ ruggedness and simplicity proved them to be reliable, and its high roll rate and good handling at low altitude made it a versatile platform that was still competitive, even though its rather sluggish acceleration turned out to be a serious weak spot, esp. in the country’s typical mountainous terrain. Its relatively low range with internal fuel only was another operational problem.
The Mystère IVEs were finally retired in 1988 and replaced by Mirage F.1C fighters from France and IAI Kfir C.7 fighter bombers from Israel.
General characteristics:
Crew: 1
Length: 12.89 m (42 ft 3 in)
Wingspan: 11.12 m (36 ft 6 in)
Height: 4.6 m (15 ft 1 in)
Wing area: 32.06 m² (345.1 sq ft)
Empty weight: 5,860 kg (12,919 lb)
Gross weight: 8,510 kg (18,761 lb)
Max takeoff weight: 9,500 kg (20,944 lb)
Powerplant:
1× Rolls-Royce Tay 250 centrifugal-flow turbojet engine with 34.32 kN (7,720 lbf) thrust
Performance:
Maximum speed: 1,110 km/h (690 mph, 600 kn) at sea level
Range: 915 km (569 mi, 494 nmi) with internal fuel only
2,280 km (1,420 mi; 1,230 nmi) with drop tanks
Service ceiling: 15,000 m (49,000 ft)
Rate of climb: 40 m/s (7,900 ft/min)
Armament:
2× 30 mm (1.18 in) DEFA 553 cannon with 150 rounds per gun
1,000 kg (2,200 lb) of payload on four underwing hardpoints, incl. bombs, rockets or drop tanks
The kit and its assembly:
A very simple project, and basically just an OOB kit in the colors of a fictional operator. The whole thing was inspired by the question: what could have been a predecessor of the Ecuadorean Mirage F.1s? Not an existential question that might pop up frequently, but I quickly decided that the Mystère IV would have been a good/plausible contender. I found this idea even more attractive when I considered a camouflage paint scheme for it, because you only get either French or Indian machines in a uniform NMF outfit or IDF Mystères in desert camouflage (either in brown/blue or the later sand/earth/green scheme).
The kit is the venerable Matchbox Mystère IVA, even though in its Revell re-boxing. It’s a very simple affair, with partly crude details like the landing gear or the dreaded “trenches” for engraved surface details, esp. on the wings. But it goes together quite well, and with some corrections and additions you get a decent model.
The kit was basically built OOB, I just added underwings pylons with some ordnance for a fighter bomber mission: a pair of drop tanks and two SNEB missile launcher pods (tanks leftover from a Sword F-94, IIRC, and the pods from a Matchbox G.91Y). A complete tub with a floor and with side consoles (origin is uncertain, though – maybe it came from an Xtrakit Supermarin Swift?) was fitted to the cockpit and the primitive OOB ejection seat was replaced with something more convincing, pimped with seatbelts (masking tape) and ejection trigger handles (thin wire).
The flaps were lowered for a more natural look, and I added small oval boundary layer fences from a BAe Hawk as a personal twist. The clumsy front wheel, originally molded onto the strut as a single piece, was replaced with something better. The main landing gear covers were replaced with thinner styrene sheet material (the OOB parts are VERY thick) and pieces from hollow steel needles were implanted into the respective fairings as gun barrels.
A thinner pitot, created from heated sprue material, was used instead of the rather massive OOB part. The ranging radar fairing in the intake was slightly enlarged with the help of white glue. And, finally, a piece of sprue was implanted into the fin’s base as a brake parachute fairing, reminiscent of the Polish Lim-6/7, license-produced MiG-17s.
Painting and markings:
Actually quite conservative, with a typical Seventies paint scheme in dark grey/dark green. I even considered a more exotic three-tone scheme but found that – together with the colorful national markings – this would look too busy. Since there is no reference for a Mystère IV in such a guise, I simply adapted the standard pattern from a Royal Air Force Supermarine Swift. For a different look than the standard RAF colors – after all, the fictional Ecuadorean Mystère IVs were painted with domestic material. I used Humbrol 75 (Bronze Green) and ModelMaster 2057 (FS 36173, USAF Neutral Grey) for a good contrast between the upper tones, with Humbrol 56 (Alu Dope) underneath.
The tail section received a burned metal look, using Revell 91 (Iron) and some graphite. The cockpit interior was painted in a very dark grey (Revell 09, Anthracite) while the landing gear became silver-grey and the wells zinc-chromate primer (Humbrol 81). For some contrast, the drop tanks became shiny aluminum (Revell 99).
The kit received a light black ink washing, primarily for the recessed panel lines, and a subtle panel post-shading – for a less uniform surface than for true weathering, I’d imagine that the aircraft would be looked after well. However, some gun soot stains around the weapon ports were added with graphite, too.
The Ecuadorean roundels and unit markings came from an Xtradecal Strikemaster sheet, the tactical codes from a Croco Decal sheet for various South-American trainers. The flag on the rudder was, due to its sweep, painted, and most stencils were taken from the Mystère’s OOB sheet or procured from an Ecuadorian Mirage V on a Carpena sheet.
Finally, the kit was sealed with matt acrylic varnish, the ordnance was added and the position lights on the wing tips were created with silver and clear paint on top of that.
Well, this was not a spectacular conversion build, rather an OOB travesty with some cosmetic changes. However, the rather classic grey/green camouflage suits the tubby aircraft well and the bright national insignia really stand out on it – a pretty combo. The whole package as fictional Mystère IVE looks surprisingly convincing!
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
Some background:
When Marcel Dassault started work on jet-powered fighters after WWII, the development evolved in gradual steps instead of quantum leaps, leading to a long line of aircraft. The Mystère IV was an evolutionary development of the Mystère II aircraft. Although bearing an external resemblance to the earlier aircraft, the Mystère IV was in fact a new design with aerodynamic improvements for supersonic flight. The prototype first flew on 28 September 1952, and the aircraft entered service in April 1953. The first 50 Mystere IVA production aircraft were powered by British Rolls-Royce Tay turbojets, while the remainder had the French-built Hispano-Suiza Verdon 350 version of that engine.
France was the main operator of the Mystère IV. In April 1953 the United States government and the United States Air Force placed an order for 223 aircraft to be operated by the French, and at the peak usage the Armée de l‘air operated 6 squadrons. Most of the aircraft were purchased under a United States Offshore Procurement contract and many were returned to US custody after they were retired. The Mystère IVs were used in the 1956 Suez Crisis and continued to remain in French service into the 1980s, even though they were quickly relegated into second line duties as more capable types like the Super Mystère SM2B or the Mirage III entered service.
Other international operators included Israel (using about sixty Mystère IVs in large-scale combat during the 1967 Six Day War), India (104 aircraft procured in 1957 and extensively used in the Indo-Pakistani War of 1965) and Ecuador.
The Fuerza Aérea Ecuatoriana (FAE, Ecuadorian Air Force) was officially created on October 27, 1920. However, like in many other countries, military flying activity already started before the formal date of birth of the Air Force. By 1939 the Ecuadorian Air Force was still limited to about 30 aircraft, though, and a staff of about 60, including 10 officers. Military aviation did not start in earnest until the early forties when an Ecuadorian mission to the United States resulted in the delivery of an assortment of aircraft for the Aviation school at Salinas: three Ryan PT-22 Recruits, six Curtiss-Wright CW-22 Falcons, six Fairchild PT-19A Cornells and three North American AT-6A Harvards arrived in March 1942, considerably boosting the capacity of the Escuela de Aviación at Salinas.
The 1950s and 1960s saw a further necessary buildup of the air force, gaining more units and aircraft, while efforts were made in enhancing the facilities at various airbases. In May 1961 the "First Air Zone" with its subordinate unit Ala de Transportes No.11 was founded. The "Second Air Zone" controlled the units in the southern half of Ecuador, Ala de Combate No.21 at Taura, Ala de Rescate No.22 at Guayaquil and Ala de Combate No.23 at Manta as well as the Escuela Superior Militar de Aviación "Cosme Rennella B." (ESMA) at Salinas.
It was at this time that the FAE was looking for a capable (yet affordable) jet fighter that would replace the vintage F-47 “Thunderbolt” piston engine fighters of American origin that had been operated since 1947 as well as the ageing fleet of Gloster Meteor jet fighters. After consulting various options, including the British Hawker Hunter and the American F-86 Sabre, Ecuador settled upon the French Mystère IV. A total of 32 aircraft were ordered in 1958 and delivered until early 1963 in two tranches, subsequently outfitting two combat squadrons.
The Ecuadorian aircraft resembled the early French Mystère IV standard and were powered by the British Rolls-Royce Tay 250. However, they differed in small details and incorporated some updates, leading to the individual designation Mystère IVE (for Ecuador). This included a modified instrumentation and a British Martin Baker ejection seat in the cockpit. On the outside, a fairing for a brake parachute at the fin’s base was the most obvious change, and there were small oval boundary layer fences on the wings’ leading edges that improved the aircraft’s handling. The front landing gear was slightly different, too, now outfitted with a mudguard.
To improve the aircraft’s capabilities in air-to-air combat, an American AN/APG-30 range-finding radar was fitted, mounted to the center of the air intake (under a slightly enlarged radome) and linked with the gyroscopic gunsight in the cockpit. It was effective at a range of up to 2.750 m, but only covered a narrow cone directly in front of the aircraft. Initially the aircraft were operated as pure fighters/interceptors, but soon they also took over ground attack and CAS missions with iron bombs and unguided missiles, even though the Mystère IV’s ordnance capacity was rather limited. But the aircraft had a good handling at low altitude and were a stable weapon platform, so that the pilots operated them with confidence.
In the early Seventies, Ecuador had plans to upgrade its Mystères with Pratt & Whitney J48-P-5 engines, a license-built version of the Rolls-Royce Tay from the USA and outfitted with an afterburner. With reheat the J48 delivered 8,750 lbf (38.9 kN) of thrust, but continuous dry thrust was only 6,350 lbf (28.2 kN), markedly less than the old Tay engine. The high fuel consumption with operating afterburner would have markedly limited the aircraft’s range, and this engine switch would have necessitated major modifications to the aircrafts’ tail section, so that the upgrade eventually did not come to fruition due the lack of funds and the rather limited and only temporary improvement in performance.
Nevertheless, in course of their career in Ecuador, the Mystères’ still underwent some modifications and modernizations. In the early Seventies an MLU program was carried out: the retractable pannier for unguided missiles was deleted in favor of an extra fuel tank and upgraded navigational and weapon avionics. The latter included wirings for IR-guided AIM-9B Sidewinder AAMs on the outer underwing pylons, what greatly improved the aircraft’s air-to-air capabilities. The original DEFA 552 guns were replaced with more modern DEFA 553s, which had a new feed system, a nitro-chrome plated steel barrel (which was longer than the 552’s and now protruded visibly from the openings), a forged drum casing, and improved electrical reliability. During this upgrade phase the machines also lost their original natural metal livery and they received a less conspicuous tactical NATO-style grey/green paint scheme with metallic-grey undersides.
In this form the Ecuadorean Mystère IVEs soldiered on well into the Eighties, with a very good reliability record. During their active career they even saw “hot” action on several occasions, for instance in a continuous border dispute with Peru, the so-called Paquisha War. This brief military clash over the control of three watch posts flared up in January 1981 and the Mystères became involved. The first incident was a dogfight with an A-37B of the Fuerza Aérea del Peru (FAP), launched from Guayaquil to intercept it – with no casualities, though. Several similar interception incidents happened until early February 1981, and the FAE Mystères also flew several CAS missions to repel the Peruvian Jungle Infantry and to support Ecuadorian ground forces. Despite their age, the aircrafts’ ruggedness and simplicity proved them to be reliable, and its high roll rate and good handling at low altitude made it a versatile platform that was still competitive, even though its rather sluggish acceleration turned out to be a serious weak spot, esp. in the country’s typical mountainous terrain. Its relatively low range with internal fuel only was another operational problem.
The Mystère IVEs were finally retired in 1988 and replaced by Mirage F.1C fighters from France and IAI Kfir C.7 fighter bombers from Israel.
General characteristics:
Crew: 1
Length: 12.89 m (42 ft 3 in)
Wingspan: 11.12 m (36 ft 6 in)
Height: 4.6 m (15 ft 1 in)
Wing area: 32.06 m² (345.1 sq ft)
Empty weight: 5,860 kg (12,919 lb)
Gross weight: 8,510 kg (18,761 lb)
Max takeoff weight: 9,500 kg (20,944 lb)
Powerplant:
1× Rolls-Royce Tay 250 centrifugal-flow turbojet engine with 34.32 kN (7,720 lbf) thrust
Performance:
Maximum speed: 1,110 km/h (690 mph, 600 kn) at sea level
Range: 915 km (569 mi, 494 nmi) with internal fuel only
2,280 km (1,420 mi; 1,230 nmi) with drop tanks
Service ceiling: 15,000 m (49,000 ft)
Rate of climb: 40 m/s (7,900 ft/min)
Armament:
2× 30 mm (1.18 in) DEFA 553 cannon with 150 rounds per gun
1,000 kg (2,200 lb) of payload on four underwing hardpoints, incl. bombs, rockets or drop tanks
The kit and its assembly:
A very simple project, and basically just an OOB kit in the colors of a fictional operator. The whole thing was inspired by the question: what could have been a predecessor of the Ecuadorean Mirage F.1s? Not an existential question that might pop up frequently, but I quickly decided that the Mystère IV would have been a good/plausible contender. I found this idea even more attractive when I considered a camouflage paint scheme for it, because you only get either French or Indian machines in a uniform NMF outfit or IDF Mystères in desert camouflage (either in brown/blue or the later sand/earth/green scheme).
The kit is the venerable Matchbox Mystère IVA, even though in its Revell re-boxing. It’s a very simple affair, with partly crude details like the landing gear or the dreaded “trenches” for engraved surface details, esp. on the wings. But it goes together quite well, and with some corrections and additions you get a decent model.
The kit was basically built OOB, I just added underwings pylons with some ordnance for a fighter bomber mission: a pair of drop tanks and two SNEB missile launcher pods (tanks leftover from a Sword F-94, IIRC, and the pods from a Matchbox G.91Y). A complete tub with a floor and with side consoles (origin is uncertain, though – maybe it came from an Xtrakit Supermarin Swift?) was fitted to the cockpit and the primitive OOB ejection seat was replaced with something more convincing, pimped with seatbelts (masking tape) and ejection trigger handles (thin wire).
The flaps were lowered for a more natural look, and I added small oval boundary layer fences from a BAe Hawk as a personal twist. The clumsy front wheel, originally molded onto the strut as a single piece, was replaced with something better. The main landing gear covers were replaced with thinner styrene sheet material (the OOB parts are VERY thick) and pieces from hollow steel needles were implanted into the respective fairings as gun barrels.
A thinner pitot, created from heated sprue material, was used instead of the rather massive OOB part. The ranging radar fairing in the intake was slightly enlarged with the help of white glue. And, finally, a piece of sprue was implanted into the fin’s base as a brake parachute fairing, reminiscent of the Polish Lim-6/7, license-produced MiG-17s.
Painting and markings:
Actually quite conservative, with a typical Seventies paint scheme in dark grey/dark green. I even considered a more exotic three-tone scheme but found that – together with the colorful national markings – this would look too busy. Since there is no reference for a Mystère IV in such a guise, I simply adapted the standard pattern from a Royal Air Force Supermarine Swift. For a different look than the standard RAF colors – after all, the fictional Ecuadorean Mystère IVs were painted with domestic material. I used Humbrol 75 (Bronze Green) and ModelMaster 2057 (FS 36173, USAF Neutral Grey) for a good contrast between the upper tones, with Humbrol 56 (Alu Dope) underneath.
The tail section received a burned metal look, using Revell 91 (Iron) and some graphite. The cockpit interior was painted in a very dark grey (Revell 09, Anthracite) while the landing gear became silver-grey and the wells zinc-chromate primer (Humbrol 81). For some contrast, the drop tanks became shiny aluminum (Revell 99).
The kit received a light black ink washing, primarily for the recessed panel lines, and a subtle panel post-shading – for a less uniform surface than for true weathering, I’d imagine that the aircraft would be looked after well. However, some gun soot stains around the weapon ports were added with graphite, too.
The Ecuadorean roundels and unit markings came from an Xtradecal Strikemaster sheet, the tactical codes from a Croco Decal sheet for various South-American trainers. The flag on the rudder was, due to its sweep, painted, and most stencils were taken from the Mystère’s OOB sheet or procured from an Ecuadorian Mirage V on a Carpena sheet.
Finally, the kit was sealed with matt acrylic varnish, the ordnance was added and the position lights on the wing tips were created with silver and clear paint on top of that.
Well, this was not a spectacular conversion build, rather an OOB travesty with some cosmetic changes. However, the rather classic grey/green camouflage suits the tubby aircraft well and the bright national insignia really stand out on it – a pretty combo. The whole package as fictional Mystère IVE looks surprisingly convincing!
+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
Some background:
When Marcel Dassault started work on jet-powered fighters after WWII, the development evolved in gradual steps instead of quantum leaps, leading to a long line of aircraft. The Mystère IV was an evolutionary development of the Mystère II aircraft. Although bearing an external resemblance to the earlier aircraft, the Mystère IV was in fact a new design with aerodynamic improvements for supersonic flight. The prototype first flew on 28 September 1952, and the aircraft entered service in April 1953. The first 50 Mystere IVA production aircraft were powered by British Rolls-Royce Tay turbojets, while the remainder had the French-built Hispano-Suiza Verdon 350 version of that engine.
France was the main operator of the Mystère IV. In April 1953 the United States government and the United States Air Force placed an order for 223 aircraft to be operated by the French, and at the peak usage the Armée de l‘air operated 6 squadrons. Most of the aircraft were purchased under a United States Offshore Procurement contract and many were returned to US custody after they were retired. The Mystère IVs were used in the 1956 Suez Crisis and continued to remain in French service into the 1980s, even though they were quickly relegated into second line duties as more capable types like the Super Mystère SM2B or the Mirage III entered service.
Other international operators included Israel (using about sixty Mystère IVs in large-scale combat during the 1967 Six Day War), India (104 aircraft procured in 1957 and extensively used in the Indo-Pakistani War of 1965) and Ecuador.
The Fuerza Aérea Ecuatoriana (FAE, Ecuadorian Air Force) was officially created on October 27, 1920. However, like in many other countries, military flying activity already started before the formal date of birth of the Air Force. By 1939 the Ecuadorian Air Force was still limited to about 30 aircraft, though, and a staff of about 60, including 10 officers. Military aviation did not start in earnest until the early forties when an Ecuadorian mission to the United States resulted in the delivery of an assortment of aircraft for the Aviation school at Salinas: three Ryan PT-22 Recruits, six Curtiss-Wright CW-22 Falcons, six Fairchild PT-19A Cornells and three North American AT-6A Harvards arrived in March 1942, considerably boosting the capacity of the Escuela de Aviación at Salinas.
The 1950s and 1960s saw a further necessary buildup of the air force, gaining more units and aircraft, while efforts were made in enhancing the facilities at various airbases. In May 1961 the "First Air Zone" with its subordinate unit Ala de Transportes No.11 was founded. The "Second Air Zone" controlled the units in the southern half of Ecuador, Ala de Combate No.21 at Taura, Ala de Rescate No.22 at Guayaquil and Ala de Combate No.23 at Manta as well as the Escuela Superior Militar de Aviación "Cosme Rennella B." (ESMA) at Salinas.
It was at this time that the FAE was looking for a capable (yet affordable) jet fighter that would replace the vintage F-47 “Thunderbolt” piston engine fighters of American origin that had been operated since 1947 as well as the ageing fleet of Gloster Meteor jet fighters. After consulting various options, including the British Hawker Hunter and the American F-86 Sabre, Ecuador settled upon the French Mystère IV. A total of 32 aircraft were ordered in 1958 and delivered until early 1963 in two tranches, subsequently outfitting two combat squadrons.
The Ecuadorian aircraft resembled the early French Mystère IV standard and were powered by the British Rolls-Royce Tay 250. However, they differed in small details and incorporated some updates, leading to the individual designation Mystère IVE (for Ecuador). This included a modified instrumentation and a British Martin Baker ejection seat in the cockpit. On the outside, a fairing for a brake parachute at the fin’s base was the most obvious change, and there were small oval boundary layer fences on the wings’ leading edges that improved the aircraft’s handling. The front landing gear was slightly different, too, now outfitted with a mudguard.
To improve the aircraft’s capabilities in air-to-air combat, an American AN/APG-30 range-finding radar was fitted, mounted to the center of the air intake (under a slightly enlarged radome) and linked with the gyroscopic gunsight in the cockpit. It was effective at a range of up to 2.750 m, but only covered a narrow cone directly in front of the aircraft. Initially the aircraft were operated as pure fighters/interceptors, but soon they also took over ground attack and CAS missions with iron bombs and unguided missiles, even though the Mystère IV’s ordnance capacity was rather limited. But the aircraft had a good handling at low altitude and were a stable weapon platform, so that the pilots operated them with confidence.
In the early Seventies, Ecuador had plans to upgrade its Mystères with Pratt & Whitney J48-P-5 engines, a license-built version of the Rolls-Royce Tay from the USA and outfitted with an afterburner. With reheat the J48 delivered 8,750 lbf (38.9 kN) of thrust, but continuous dry thrust was only 6,350 lbf (28.2 kN), markedly less than the old Tay engine. The high fuel consumption with operating afterburner would have markedly limited the aircraft’s range, and this engine switch would have necessitated major modifications to the aircrafts’ tail section, so that the upgrade eventually did not come to fruition due the lack of funds and the rather limited and only temporary improvement in performance.
Nevertheless, in course of their career in Ecuador, the Mystères’ still underwent some modifications and modernizations. In the early Seventies an MLU program was carried out: the retractable pannier for unguided missiles was deleted in favor of an extra fuel tank and upgraded navigational and weapon avionics. The latter included wirings for IR-guided AIM-9B Sidewinder AAMs on the outer underwing pylons, what greatly improved the aircraft’s air-to-air capabilities. The original DEFA 552 guns were replaced with more modern DEFA 553s, which had a new feed system, a nitro-chrome plated steel barrel (which was longer than the 552’s and now protruded visibly from the openings), a forged drum casing, and improved electrical reliability. During this upgrade phase the machines also lost their original natural metal livery and they received a less conspicuous tactical NATO-style grey/green paint scheme with metallic-grey undersides.
In this form the Ecuadorean Mystère IVEs soldiered on well into the Eighties, with a very good reliability record. During their active career they even saw “hot” action on several occasions, for instance in a continuous border dispute with Peru, the so-called Paquisha War. This brief military clash over the control of three watch posts flared up in January 1981 and the Mystères became involved. The first incident was a dogfight with an A-37B of the Fuerza Aérea del Peru (FAP), launched from Guayaquil to intercept it – with no casualities, though. Several similar interception incidents happened until early February 1981, and the FAE Mystères also flew several CAS missions to repel the Peruvian Jungle Infantry and to support Ecuadorian ground forces. Despite their age, the aircrafts’ ruggedness and simplicity proved them to be reliable, and its high roll rate and good handling at low altitude made it a versatile platform that was still competitive, even though its rather sluggish acceleration turned out to be a serious weak spot, esp. in the country’s typical mountainous terrain. Its relatively low range with internal fuel only was another operational problem.
The Mystère IVEs were finally retired in 1988 and replaced by Mirage F.1C fighters from France and IAI Kfir C.7 fighter bombers from Israel.
General characteristics:
Crew: 1
Length: 12.89 m (42 ft 3 in)
Wingspan: 11.12 m (36 ft 6 in)
Height: 4.6 m (15 ft 1 in)
Wing area: 32.06 m² (345.1 sq ft)
Empty weight: 5,860 kg (12,919 lb)
Gross weight: 8,510 kg (18,761 lb)
Max takeoff weight: 9,500 kg (20,944 lb)
Powerplant:
1× Rolls-Royce Tay 250 centrifugal-flow turbojet engine with 34.32 kN (7,720 lbf) thrust
Performance:
Maximum speed: 1,110 km/h (690 mph, 600 kn) at sea level
Range: 915 km (569 mi, 494 nmi) with internal fuel only
2,280 km (1,420 mi; 1,230 nmi) with drop tanks
Service ceiling: 15,000 m (49,000 ft)
Rate of climb: 40 m/s (7,900 ft/min)
Armament:
2× 30 mm (1.18 in) DEFA 553 cannon with 150 rounds per gun
1,000 kg (2,200 lb) of payload on four underwing hardpoints, incl. bombs, rockets or drop tanks
The kit and its assembly:
A very simple project, and basically just an OOB kit in the colors of a fictional operator. The whole thing was inspired by the question: what could have been a predecessor of the Ecuadorean Mirage F.1s? Not an existential question that might pop up frequently, but I quickly decided that the Mystère IV would have been a good/plausible contender. I found this idea even more attractive when I considered a camouflage paint scheme for it, because you only get either French or Indian machines in a uniform NMF outfit or IDF Mystères in desert camouflage (either in brown/blue or the later sand/earth/green scheme).
The kit is the venerable Matchbox Mystère IVA, even though in its Revell re-boxing. It’s a very simple affair, with partly crude details like the landing gear or the dreaded “trenches” for engraved surface details, esp. on the wings. But it goes together quite well, and with some corrections and additions you get a decent model.
The kit was basically built OOB, I just added underwings pylons with some ordnance for a fighter bomber mission: a pair of drop tanks and two SNEB missile launcher pods (tanks leftover from a Sword F-94, IIRC, and the pods from a Matchbox G.91Y). A complete tub with a floor and with side consoles (origin is uncertain, though – maybe it came from an Xtrakit Supermarin Swift?) was fitted to the cockpit and the primitive OOB ejection seat was replaced with something more convincing, pimped with seatbelts (masking tape) and ejection trigger handles (thin wire).
The flaps were lowered for a more natural look, and I added small oval boundary layer fences from a BAe Hawk as a personal twist. The clumsy front wheel, originally molded onto the strut as a single piece, was replaced with something better. The main landing gear covers were replaced with thinner styrene sheet material (the OOB parts are VERY thick) and pieces from hollow steel needles were implanted into the respective fairings as gun barrels.
A thinner pitot, created from heated sprue material, was used instead of the rather massive OOB part. The ranging radar fairing in the intake was slightly enlarged with the help of white glue. And, finally, a piece of sprue was implanted into the fin’s base as a brake parachute fairing, reminiscent of the Polish Lim-6/7, license-produced MiG-17s.
Painting and markings:
Actually quite conservative, with a typical Seventies paint scheme in dark grey/dark green. I even considered a more exotic three-tone scheme but found that – together with the colorful national markings – this would look too busy. Since there is no reference for a Mystère IV in such a guise, I simply adapted the standard pattern from a Royal Air Force Supermarine Swift. For a different look than the standard RAF colors – after all, the fictional Ecuadorean Mystère IVs were painted with domestic material. I used Humbrol 75 (Bronze Green) and ModelMaster 2057 (FS 36173, USAF Neutral Grey) for a good contrast between the upper tones, with Humbrol 56 (Alu Dope) underneath.
The tail section received a burned metal look, using Revell 91 (Iron) and some graphite. The cockpit interior was painted in a very dark grey (Revell 09, Anthracite) while the landing gear became silver-grey and the wells zinc-chromate primer (Humbrol 81). For some contrast, the drop tanks became shiny aluminum (Revell 99).
The kit received a light black ink washing, primarily for the recessed panel lines, and a subtle panel post-shading – for a less uniform surface than for true weathering, I’d imagine that the aircraft would be looked after well. However, some gun soot stains around the weapon ports were added with graphite, too.
The Ecuadorean roundels and unit markings came from an Xtradecal Strikemaster sheet, the tactical codes from a Croco Decal sheet for various South-American trainers. The flag on the rudder was, due to its sweep, painted, and most stencils were taken from the Mystère’s OOB sheet or procured from an Ecuadorian Mirage V on a Carpena sheet.
Finally, the kit was sealed with matt acrylic varnish, the ordnance was added and the position lights on the wing tips were created with silver and clear paint on top of that.
Well, this was not a spectacular conversion build, rather an OOB travesty with some cosmetic changes. However, the rather classic grey/green camouflage suits the tubby aircraft well and the bright national insignia really stand out on it – a pretty combo. The whole package as fictional Mystère IVE looks surprisingly convincing!