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Countershading
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] |
Counter-illumination
Counter-illumination is a method of active camouflage seen in marine animals such as firefly squid and midshipman fish, and in military prototypes, producing light to match their backgrounds in both brightness and wavelength. Marine animals of the mesopelagic (mid-water) zone tend to appear dark against the bright water surface when seen from below. They can camouflage themselves, often from predators but also from their prey, by producing light with bioluminescent photophores on their downward-facing surfaces, reducing the contrast of their silhouettes against the background. The light may be produced by the animals themselves, or by symbiotic bacteria, often ''Aliivibrio fischeri''. Counter-illumination differs from countershading, which uses only pigments such as melanin to reduce the appearance of shadows. It is one of the dominant types of aquatic camouflage, along with transparency and silvering. All three methods make animals in open water resemble their environment. C ... [...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] |
Animal Coloration
Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peafowl, the male has strong patterns, conspicuous colours and is iridescent, while the female is far less visible. There are several separate reasons why animals have evolved colours. Camouflage enables an animal to remain hidden from view. Animals use colour to advertise services such as cleaning to animals of other species; to signal their sexual status to other members of the same species; and in mimicry, taking advantage of the warning coloration of another species. Some animals use flashes of colour to divert attacks by startling predators. Zebras may possibly use motion dazzle, confusing a predator's attack by moving a bold pattern rapidly. Some animals are coloured for physical protection, with pigments in the skin to protect against sunburn, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zoologist
Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological classification, classification, Ethology, habits, and distribution of all animals, both living and extinction, extinct, and how they interact with their ecosystems. The term is derived from Ancient Greek , ('animal'), and , ('knowledge', 'study'). Although humans have always been interested in the natural history of the animals they saw around them, and made use of this knowledge to domesticate certain species, the formal study of zoology can be said to have originated with Aristotle. He viewed animals as living organisms, studied their structure and development, and considered their adaptations to their surroundings and the function of their parts. The Greek physician Galen studied human anatomy and was one of the greatest surgeons of the a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe by the North Sea to the east and the English Channel to the south. The country covers five-eighths of the island of Great Britain, which lies in the North Atlantic, and includes over 100 smaller islands, such as the Isles of Scilly and the Isle of Wight. The area now called England was first inhabited by modern humans during the Upper Paleolithic period, but takes its name from the Angles, a Germanic tribe deriving its name from the Anglia peninsula, who settled during the 5th and 6th centuries. England became a unified state in the 10th century and has had a significant cultural and legal impact on the wider world since the Age of Discovery, which began during the 15th century. The English language, the Anglican Church, and Engli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luna Moth
The Luna moth (''Actias luna'') also known as the American moon moth is a Nearctic moth in the family Saturniidae, subfamily Saturniinae, a group commonly known as giant silk moths. It has lime-green colored wings and a white body. The larvae (caterpillars) are also green. Typically, it has a wingspan of roughly , but can exceed , making it one of the larger moths in North America. Across Canada, it has one generation per year, with the winged adults appearing in late May or early June, whereas farther south it will have two or even three generations per year, the first appearance as early as March in southern parts of the United States. As defense mechanisms, larvae emit clicks as a warning and can also regurgitate intestinal contents, confirmed as having a deterrent effect on a variety of predators. The elongated tails of the hindwings are thought to confuse the echolocation detection used by predatory bats. A parasitoid fly deliberately introduced to North America to be a b ... [...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] |
Marine Organisms
Marine life, sea life, or ocean life is the aquatic plant, plants, aquatic animal, animals and other organisms that live in the seawater, salt water of seas or oceans, or the brackish water of coastal estuary, estuaries. At a fundamental level, marine life affects the nature of the planet. Marine organisms, mostly marine microorganisms, microorganisms, oxygen cycle, produce oxygen and biosequestration, sequester carbon. Marine life in part shape and protect shorelines, and some marine organisms even help create new land (e.g. coral building coral reef, reefs). Most life forms evolved initially in marine habitats. By volume, oceans provide about 90% of the living space on the planet. The earliest vertebrates appeared in the form of fish, which live exclusively in water. Some of these evolved into amphibians, which spend portions of their lives in water and portions on land. One group of amphibians evolved into reptiles and mammals and a few subsets of each returned to the ocean ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
