|
Countershaded
Countershading, or Thayer's law, is a method of camouflage in which an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptiles, birds, fish, and insects, both in predators and in prey. When light falls from above on a uniformly coloured three-dimensional object such as a sphere, it makes the upper side appear lighter and the underside darker, grading from one to the other. This pattern of light and shade makes the object appear solid, and therefore easier to detect. The classical form of countershading, discovered in 1909 by the artist Abbott Handerson Thayer, works by counterbalancing the effects of self-shadowing, again typically with grading from dark to light. In theory this could be useful for military camouflage, but in practice it has rarely been applied, despite the best efforts of Thayer and, later, in the Second World War, of the zoologist Hugh Cott. The precise functi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camouflage
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the battledress of a modern soldier, and the leaf-mimic katydid's wings. A third approach, motion dazzle, confuses the observer with a conspicuous pattern, making the object visible but momentarily harder to locate, as well as making general aiming easier. The majority of camouflage methods aim for crypsis, often through a general resemblance to the background, high contrast disruptive coloration, eliminating shadow, and countershading. In the open ocean, where there is no background, the principal methods of camouflage are transparency, silvering, and countershading, while the ability to produce light is among other things used for counter-illumination on the undersides of cephalopods such as squid. Some animals, such as chameleons and o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hugh Cott
Hugh Bamford Cott (6 July 1900 – 18 April 1987) was a British zoologist, an authority on both natural and military camouflage, and a scientific illustrator and photographer. Many of his field studies took place in Africa, where he was especially interested in the Nile crocodile, the evolution of pattern and colour in animals. During the World War II, Second World War, Cott worked as a camouflage expert for the British Army and helped to influence War Office policy on camouflage. His book ''Adaptive Coloration in Animals'' (1940), popular among serving soldiers, was the major textbook on camouflage in zoology of the twentieth century. After the war, he became a Fellow of Selwyn College, Cambridge. As a Fellow of the Zoological Society of London, he undertook expeditions to Africa and the Amazon to collect specimens, mainly reptiles and amphibians. Life and career Cott was born in Ashby Magna, Leicestershire, England, on 6 July 1900; his father was the Rector (ecclesiastical), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Military Camouflage
Military camouflage is the use of camouflage by an armed force to protect personnel and equipment from observation by enemy forces. In practice, this means applying colour and materials to military equipment of all kinds, including vehicles, ships, aircraft, gun positions and battledress, either to conceal it from observation ( crypsis), or to make it appear as something else (mimicry). The French slang word ''camouflage'' came into common English usage during World War I when the concept of visual deception developed into an essential part of modern military tactics. In that war, long-range artillery and observation from the air combined to expand the field of fire, and camouflage was widely used to decrease the danger of being targeted or to enable surprise. As such, military camouflage is a form of military deception. Camouflage was first practiced in simple form in the mid 18th century by rifle units. Their tasks required them to be inconspicuous, and they were issued gree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abbott Handerson Thayer
Abbott Handerson Thayer (August 12, 1849May 29, 1921) was an American artist, naturalist and teacher. As a painter of portraits, figures, animals and landscapes, he enjoyed a certain prominence during his lifetime, and his paintings are represented in the major American art collections. He is perhaps best known for his 'angel' paintings, some of which use his children as models. During the last third of his life, he worked together with his son, Gerald Handerson Thayer, on a book about protective coloration in nature, titled ''Concealing-Coloration in the Animal Kingdom''. First published by Macmillan in 1909, then reissued in 1918, it may have had an effect on military camouflage during World War I. However it was roundly mocked by Theodore Roosevelt and others for its assumption that all animal coloration is cryptic. Thayer also influenced American art through his efforts as a teacher, training apprentices in his New Hampshire studio. Early life Thayer was born in Boston t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deimatic Behaviour
Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey animal an opportunity to escape. The term deimatic or dymantic originates from the Greek δειματόω (deimatóo), meaning "to frighten". Deimatic display occurs in widely separated groups of animals, including moths, butterflies, mantises and phasmids among the insects. In the cephalopods, different species of octopuses, squids, cuttlefish and the paper nautilus are deimatic. Displays are classified as deimatic or aposematic by the responses of the animals that see them. Where predators are initially startled but learn to eat the displaying prey, the display is classed as deimatic, and the prey is bluffing; where they continue to avoid the prey after tasting it, the display is taken as aposematic, meaning the prey is genuinely distastef ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squid
True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting these criteria. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius (cephalopod), gladius or pen, made of chitin. Squid diverged from other cephalopods during the Jurassic and occupy a similar role to teleost fish as open water predators of similar size and behaviour. They play an important role in the open water food web. The two long tentacles are used to grab prey and the eight arms to hold and control it. The beak then cuts the food into suitable size chunks for swallowing. Squid are rapid swimmers, moving by Aquatic locomotion#Jet propulsion, jet propulsion, and largely locate their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prototype
A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototype is generally used to evaluate a new design to enhance precision by system analysts and users. Prototyping serves to provide specifications for a real, working system rather than a theoretical one. In some design workflow models, creating a prototype (a process sometimes called materialization) is the step between the Formal specification, formalization and the evaluation of an idea. A prototype can also mean a typical example of something such as in the use of the derivation 'prototypical'. This is a useful term in identifying objects, behaviours and concepts which are considered the accepted norm and is analogous with terms such as stereotypes and archetypes. The word ''wikt:prototype, prototype'' derives from the Greek language, Greek ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skunk
Skunks are mammals in the family Mephitidae. They are known for their ability to spray a liquid with a strong, unpleasant scent from their anal glands. Different species of skunk vary in appearance from black-and-white to brown, cream or ginger colored, but all have warning coloration. While related to polecats and other members of the weasel family, skunks have as their closest relatives the Old World stink badgers. Taxonomy In alphabetical order, the living species of skunks are: * Family Mephitidae ** Genus: ''Conepatus'' *** ''Conepatus chinga'' – Molina's hog-nosed skunk *** ''Conepatus humboldtii'' – Humboldt's hog-nosed skunk *** ''Conepatus leuconotus'' – American hog-nosed skunk *** ''Conepatus semistriatus'' – striped hog-nosed skunk ** Genus: '' Mephitis'' *** ''Mephitis macroura'' – hooded skunk *** ''Mephitis mephitis'' – striped skunk ** Genus: ''Spilogale'' *** ''Spilogale angustifrons'' – southern spotted s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aposematism
Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or smell, sharp spines, or aggressive nature. These advertising signals may take the form of conspicuous coloration, sounds, odours, or other perceivable characteristics. Aposematic signals are beneficial for both predator and prey, since both avoid potential harm. The term was coined in 1877 by Edward Bagnall Poulton for Alfred Russel Wallace's concept of warning coloration. Aposematism is exploited in Müllerian mimicry, where species with strong defences evolve to resemble one another. By mimicking similarly coloured species, the warning signal to predators is shared, causing them to learn more quickly at less of a cost. A genuine aposematic signal that a species actually possesses chemical or physical defences is not the only way to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signalling Theory
Within evolutionary biology, signalling theory is a body of theoretical work examining communication between individuals, both within species and across species. The central question is when organisms with conflicting interests, such as in sexual selection, should be expected to provide honest signals (no presumption being made of conscious intention) rather than cheating. Mathematical models describe how signalling can contribute to an evolutionarily stable strategy. Signals are given in contexts such as mate selection by females, which subjects the advertising males' signals to selective pressure. Signals thus evolve because they modify the behaviour of the receiver to benefit the signaller. Signals may be honest, conveying information which usefully increases the fitness of the receiver, or dishonest. An individual can cheat by giving a dishonest signal, which might briefly benefit that signaller, at the risk of undermining the signalling system for the whole population. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioluminescence
Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria, and terrestrial arthropods such as fireflies. In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from the genus ''Vibrio''; in others, it is autogenic, produced by the animals themselves. In a general sense, the principal chemical reaction in bioluminescence involves a light-emitting molecule and an enzyme, generally called luciferin and luciferase, respectively. Because these are generic names, luciferins and luciferases are often distinguished by the species or group, e.g. firefly luciferin. In all characterized cases, the enzyme catalyzes the oxidation of the luciferin. In some species, the luciferase requires other cofactors, such as calcium or magnesium ions, and somet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nile Catfish
right ''Synodontis batensoda'', the upside-down catfish, is a species of mochokid upside-down catfish. It is unevenly distributed in inland waters across Africa from Senegal to Ethiopia, and is also known as a squeaker or giant upside-down catfish. It was originally described by Eduard Rüppell in 1832 in the paper "Continuation of the description and figure of several new fish, in the Nile. p1-14". The species is now regionally extinct in Northern Africa, but used to be found in Cairo during floods. It can be found in portions of the White Nile, Blue Nile, and the Baro Rivers in northeast Africa, and the Chad, Niger, Senegal, and Gambia river basins in western Africa. It occurs in slow-moving waters and marshes bordering large rivers. Water temperatures in its native habitat range from . ''Synodontis batensoda'' is silver-green to blue-grey with black barbels and a blackish underside (thus its specific name, from Arabic بطن السوداء ''bațn sawdā''' = "black b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Squid")
