84-599: Lyncornis is a genus of eared nightjar in the family Caprimulgidae . The genus Lyncornis was introduced in 1838 by the English ornithologist John Gould with Lyncornis cerviniceps Gould 1838 as the type species . This taxon is now treated as a subspecies of the great eared nightjar . The genus name combines the Ancient Greek lunx , lunkos meaning "lynx" with ornis meaning "bird. The genus contains two species: These two species were formerly placed in
168-554: A subfamily Eurostopodinae of the Caprimulgidae but some studies have them as a sister group, while others treat them as a clade within the caprimulgids; others consider that the genus Eurostopodus may not be monophyletic. The eared nightjars consist of seven extant species in two genera, Eurostopodus and Lyncornis : The eared nightjars are large compared to many nightjars, but otherwise are similar in structure. They are long-winged and long-tailed, and are light for
252-436: A background that is brighter than an animal's body or military vehicle; it is a form of active camouflage. It is notably used by some species of squid , such as the firefly squid and the midwater squid . The latter has light-producing organs ( photophores ) scattered all over its underside; these create a sparkling glow that prevents the animal from appearing as a dark shape when seen from below. Counterillumination camouflage
336-429: A clear evolutionary advantage in plants: they would tend to escape from being eaten by herbivores . Another possibility is that some plants have leaves differently coloured on upper and lower surfaces or on parts such as veins and stalks to make green-camouflaged insects conspicuous, and thus benefit the plants by favouring the removal of herbivores by carnivores. These hypotheses are testable. Some animals, such as
420-640: A comb-like pecten on its inner edge, which may be used for plumage care. The plumage is cryptically patterned with browns and greys, to make these ground-nesting birds difficult to see when resting during the day. Some species have white patches in the wings, and the two in the genus Lyncornis (Great and Malaysian) have "ear tufts" at the rear of the crown. The songs of these birds are three or more repeated notes, sometimes with whistles or bubbling sounds, and are typically given at dawn or dusk. The eared nightjars are found from China through Southeast Asia to Australia. Tropical populations are mostly sedentary, but
504-403: A combination of the two. Most forms of camouflage are ineffective when the camouflaged animal or object moves, because the motion is easily seen by the observing predator, prey or enemy. However, insects such as hoverflies and dragonflies use motion camouflage : the hoverflies to approach possible mates, and the dragonflies to approach rivals when defending territories. Motion camouflage
588-442: A fish can be seen by a factor of 6 compared to a fish with a nominal 2% reflectance. Species with this adaptation are widely dispersed in various orders of the phylogenetic tree of bony fishes ( Actinopterygii ), implying that natural selection has driven the convergent evolution of ultra-blackness camouflage independently many times. In mimesis (also called masquerade ), the camouflaged object looks like something else which
672-475: A high contrast pattern that could be disruptive coloration, the adults are very conspicuous when in the open. Some authors have argued that adult giraffes are cryptic, since when standing among trees and bushes they are hard to see at even a few metres' distance. However, adult giraffes move about to gain the best view of an approaching predator, relying on their size and ability to defend themselves, even from lions, rather than on camouflage. A different explanation
756-519: A mirror oriented vertically makes animals such as fish invisible from the side. Most fish in the upper ocean such as sardine and herring are camouflaged by silvering. The marine hatchetfish is extremely flattened laterally, leaving the body just millimetres thick, and the body is so silvery as to resemble aluminium foil . The mirrors consist of microscopic structures similar to those used to provide structural coloration : stacks of between 5 and 10 crystals of guanine spaced about 1 ⁄ 4 of
840-404: A particularly black skin which reflected only 0.044% of 480 nm wavelength light. The ultra-blackness is achieved with a thin but continuous layer of particles in the dermis , melanosomes . These particles both absorb most of the light, and are sized and shaped so as to scatter rather than reflect most of the rest. Modelling suggests that this camouflage should reduce the distance at which such
924-411: A period of about 8000 years the single agouti gene developed 9 mutations that each made expression of yellow fur stronger under natural selection, and largely eliminated melanin-coding black fur coloration. On the other hand, all black domesticated cats have deletions of the agouti gene that prevent its expression, meaning no yellow or red color is produced. The evolution, history and widespread scope of
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#17327980828591008-502: A predator blends in with the background, enabling it to approach prey). His experiments showed that swallow-tailed moth pupae were camouflaged to match the backgrounds on which they were reared as larvae . Poulton's "general protective resemblance" was at that time considered to be the main method of camouflage, as when Frank Evers Beddard wrote in 1892 that "tree-frequenting animals are often green in colour. Among vertebrates numerous species of parrots , iguanas , tree-frogs , and
1092-409: A reason, such as to lure prey. For example, the nematocysts (stinging cells) of the transparent siphonophore Agalma okenii resemble small copepods . Examples of transparent marine animals include a wide variety of larvae , including radiata (coelenterates), siphonophores, salps (floating tunicates ), gastropod molluscs , polychaete worms, many shrimplike crustaceans , and fish; whereas
1176-693: A reproductive advantage, enabling them to leave more offspring, on average, than other members of the same species . In his Origin of Species , Darwin wrote: When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather , and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey ; and hawks are guided by eyesight to their prey, so much so, that on parts of
1260-505: A small elastic sac, which can be stretched or allowed to relax under the control of the brain to vary its opacity. By controlling chromatophores of different colours, cephalopods can rapidly change their skin patterns and colours. On a longer timescale, animals like the Arctic hare , Arctic fox , stoat , and rock ptarmigan have snow camouflage , changing their coat colour (by moulting and growing new fur or feathers) from brown or grey in
1344-509: A small group of nocturnal birds in the nightjar family, although the taxonomy is uncertain. There are seven species , mainly found in forest and scrub from China to Australia. Five species are placed in the genus Eurostopodus , the other two species in Lyncornis . They are long winged birds with plumage patterned with grey and brown to camouflage them when resting on the ground. They feed on insects caught in flight. A single white egg
1428-416: A species of nudibranch that feeds on stony coral , utilizes specific cryptic patterning in reef ecosystems. The nudibranch syphons pigments from the consumed coral into the epidermis, adopting the same shade as the consumed coral. This allows the nudibranch to change colour (mostly between black and orange) depending on the coral system that it inhabits. However, P. melanocrachia can only feed and lay eggs on
1512-409: A wavelength apart to interfere constructively and achieve nearly 100 per cent reflection. In the deep waters that the hatchetfish lives in, only blue light with a wavelength of 500 nanometres percolates down and needs to be reflected, so mirrors 125 nanometres apart provide good camouflage. In fish such as the herring which live in shallower water, the mirrors must reflect a mixture of wavelengths, and
1596-452: Is acellular and highly transparent. This conveniently makes them buoyant , but it also makes them large for their muscle mass, so they cannot swim fast, making this form of camouflage a costly trade-off with mobility. Gelatinous planktonic animals are between 50 and 90 percent transparent. A transparency of 50 percent is enough to make an animal invisible to a predator such as cod at a depth of 650 metres (2,130 ft); better transparency
1680-475: Is achieved by moving so as to stay on a straight line between the target and a fixed point in the landscape; the pursuer thus appears not to move, but only to loom larger in the target's field of vision. Some insects sway while moving to appear to be blown back and forth by the breeze. The same method can be used for military purposes, for example by missiles to minimise their risk of detection by an enemy. However, missile engineers, and animals such as bats, use
1764-433: Is an important component of camouflage in all environments. For instance, tree-dwelling parakeets are mainly green; woodcocks of the forest floor are brown and speckled; reedbed bitterns are streaked brown and buff; in each case the animal's coloration matches the hues of its habitat. Similarly, desert animals are almost all desert coloured in tones of sand, buff, ochre, and brownish grey, whether they are mammals like
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#17327980828591848-436: Is argued that these juvenile giraffes must be very well camouflaged; this is supported by coat markings being strongly inherited . The possibility of camouflage in plants was little studied until the late 20th century. Leaf variegation with white spots may serve as camouflage in forest understory plants, where there is a dappled background; leaf mottling is correlated with closed habitats. Disruptive camouflage would have
1932-418: Is common in military usage, both for uniforms and for military vehicles. Disruptive patterning, however, does not always achieve crypsis on its own, as an animal or a military target may be given away by factors like shape, shine, and shadow. The presence of bold skin markings does not in itself prove that an animal relies on camouflage, as that depends on its behaviour. For example, although giraffes have
2016-435: Is fossil evidence of camouflaged insects going back over 100 million years, for example lacewings larvae that stick debris all over their bodies much as their modern descendants do, hiding them from their prey. Dinosaurs appear to have been camouflaged, as a 120 million year old fossil of a Psittacosaurus has been preserved with countershading . Camouflage does not have a single genetic origin. However, studying
2100-403: Is implied by young giraffes being far more vulnerable to predation than adults. More than half of all giraffe calves die within a year, and giraffe mothers hide their newly born calves, which spend much of the time lying down in cover while their mothers are away feeding. The mothers return once a day to feed their calves with milk. Since the presence of a mother nearby does not affect survival, it
2184-503: Is laid directly on the ground and incubated by both adults. The chicks can walk soon after hatching. The order Caprimulgiformes contains several families of nocturnal insectivores, these are the frogmouths , the potoos , the oilbird and the nightjars . The latter family is normally split into two subfamilies, the American nighthawks , Chordelinae, and the typical nightjars Caprimulginae. The eared nightjars are sometimes considered
2268-525: Is less often used for military camouflage, despite Second World War experiments that showed its effectiveness. English zoologist Hugh Cott encouraged the use of methods including countershading, but despite his authority on the subject, failed to persuade the British authorities. Soldiers often wrongly viewed camouflage netting as a kind of invisibility cloak, and they had to be taught to look at camouflage practically, from an enemy observer's viewpoint. At
2352-434: Is mediated by a type of chromatophore known as melanophores that contain dark pigment. A melanophore is star-shaped; it contains many small pigmented organelles which can be dispersed throughout the cell, or aggregated near its centre. When the pigmented organelles are dispersed, the cell makes a patch of the animal's skin appear dark; when they are aggregated, most of the cell, and the animal's skin, appears light. In frogs,
2436-540: Is not every reason to believe it the very best conceivable device for the concealment of its wearer", and using paintings such as Peacock in the Woods (1907) to reinforce his argument. Thayer was roundly mocked for these views by critics including Teddy Roosevelt . The English zoologist Hugh Cott 's 1940 book Adaptive Coloration in Animals corrected Thayer's errors, sometimes sharply: "Thus we find Thayer straining
2520-739: Is possible that some plants use camouflage to evade being eaten by herbivores . Military camouflage was spurred by the increasing range and accuracy of firearms in the 19th century. In particular the replacement of the inaccurate musket with the rifle made personal concealment in battle a survival skill. In the 20th century, military camouflage developed rapidly, especially during the First World War . On land, artists such as André Mare designed camouflage schemes and observation posts disguised as trees. At sea , merchant ships and troop carriers were painted in dazzle patterns that were highly visible, but designed to confuse enemy submarines as to
2604-463: Is required for invisibility in shallower water, where the light is brighter and predators can see better. For example, a cod can see prey that are 98 percent transparent in optimal lighting in shallow water. Therefore, sufficient transparency for camouflage is more easily achieved in deeper waters. Some tissues such as muscles can be made transparent, provided either they are very thin or organised as regular layers or fibrils that are small compared to
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2688-483: Is the likely function of the bioluminescence of many marine organisms, though light is also produced to attract or to detect prey and for signalling. Counterillumination has rarely been used for military purposes. " Diffused lighting camouflage " was trialled by Canada's National Research Council during the Second World War. It involved projecting light on to the sides of ships to match the faint glow of
2772-428: Is their mutual resemblance." He also explained the coloration of sea fish such as the mackerel : "Among pelagic fish it is common to find the upper surface dark-coloured and the lower surface white, so that the animal is inconspicuous when seen either from above or below." The artist Abbott Handerson Thayer formulated what is sometimes called Thayer's Law, the principle of countershading . However, he overstated
2856-474: Is thought to have originated through transposition from symbiotic Aliivibrio fischeri bacteria, which provide bioluminescence to its hosts. While not all cephalopods use active camouflage , ancient cephalopods may have inherited the gene horizontally from symbiotic A. fischeri , with divergence occurred through subsequent gene duplication (such as in the case of Sepia officinalis ) or gene loss (as with cephalopods with no active camouflage capabilities). This
2940-640: Is unique as an instance of camouflage arising as an instance of horizontal gene transfer from an endosymbiont . However, other methods of horizontal gene transfer are common in the evolution of camouflage strategies in other lineages. Peppered moths and walking stick insects both have camouflage-related genes that stem from transposition events. The Agouti genes are orthologous genes involved in camouflage across many lineages. They produce yellow and red coloration ( phaeomelanin ), and work in competition with other genes that produce black (melanin) and brown (eumelanin) colours. In eastern deer mice , over
3024-548: The gerbil or fennec fox , birds such as the desert lark or sandgrouse , or reptiles like the skink or horned viper . Military uniforms, too, generally resemble their backgrounds; for example khaki uniforms are a muddy or dusty colour, originally chosen for service in South Asia. Many moths show industrial melanism , including the peppered moth which has coloration that blends in with tree bark. The coloration of these insects evolved between 1860 and 1940 to match
3108-409: The green tree-snake are examples". Beddard did however briefly mention other methods, including the "alluring coloration" of the flower mantis and the possibility of a different mechanism in the orange tip butterfly . He wrote that "the scattered green spots upon the under surface of the wings might have been intended for a rough sketch of the small flowerets of the plant [an umbellifer ], so close
3192-401: The horned lizards of North America, have evolved elaborate measures to eliminate shadow . Their bodies are flattened, with the sides thinning to an edge; the animals habitually press their bodies to the ground; and their sides are fringed with white scales which effectively hide and disrupt any remaining areas of shadow there may be under the edge of the body. The theory that the body shape of
3276-442: 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. 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
3360-600: The British army having adopted "coats of motley hue and stripes of paint" for snipers. Cott takes the example of the larva of the blotched emerald moth, which fixes a screen of fragments of leaves to its specially hooked bristles, to argue that military camouflage uses the same method, pointing out that the "device is ... essentially the same as one widely practised during the Great War for the concealment, not of caterpillars, but of caterpillar-tractors, [gun] battery positions, observation posts and so forth." Movement catches
3444-663: The Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence I can see no reason to doubt that natural selection might be most effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant. The English zoologist Edward Bagnall Poulton studied animal coloration , especially camouflage. In his 1890 book The Colours of Animals , he classified different types such as "special protective resemblance" (where an animal looks like another object), or "general aggressive resemblance" (where
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3528-409: The adults of most of these are opaque and pigmented, resembling the seabed or shores where they live. Adult comb jellies and jellyfish obey the rule, often being mainly transparent. Cott suggests this follows the more general rule that animals resemble their background: in a transparent medium like seawater, that means being transparent. The small Amazon River fish Microphilypnus amazonicus and
3612-483: The agouti gene shows that different organisms often rely on orthologous or even identical genes to develop a variety of camouflage strategies. While camouflage can increase an organism's fitness, it has genetic and energetic costs. There is a trade-off between detectability and mobility. Species camouflaged to fit a specific microhabitat are less likely to be detected when in that microhabitat, but must spend energy to reach, and sometimes to remain in, such areas. Outside
3696-438: The body outline, making it harder to precisely identify and locate. However, disruptive patterns result in higher predation. Disruptive patterns that specifically involve visible symmetry (such as in some butterflies) reduce survivability and increase predation. Some researchers argue that because wing-shape and color pattern are genetically linked, it is genetically costly to develop asymmetric wing colorations that would enhance
3780-456: The body. On these, the nymph spreads an inner layer of fine particles and an outer layer of coarser particles. The camouflage may conceal the bug from both predators and prey. Similar principles can be applied for military purposes, for instance when a sniper wears a ghillie suit designed to be further camouflaged by decoration with materials such as tufts of grass from the sniper's immediate environment. Such suits were used as early as 1916,
3864-442: The branches of host-coral, Platygyra carnosa , which limits the geographical range and efficacy in nudibranch nutritional crypsis. Furthermore, the nudibranch colour change is not immediate, and switching between coral hosts when in search for new food or shelter can be costly. The costs associated with distractive or disruptive crypsis are more complex than the costs associated with background matching. Disruptive patterns distort
3948-457: The camouflage consists of two surfaces, each with the simple function of providing concealment against a specific background, such as a bright water surface or the sky. The body of a shark or the fuselage of an aircraft is not gradated from light to dark to appear flat when seen from the side. The camouflage methods used are the matching of background colour and pattern, and disruption of outlines. Counter-illumination means producing light to match
4032-468: The case in the 1909 book Concealing-Coloration in the Animal Kingdom , arguing that "All patterns and colors whatsoever of all animals that ever preyed or are preyed on are under certain normal circumstances obliterative" (that is, cryptic camouflage), and that "Not one ' mimicry ' mark, not one ' warning color '... nor any ' sexually selected ' color, exists anywhere in the world where there
4116-403: The change is controlled relatively slowly, mainly by hormones . In fish, the change is controlled by the brain, which sends signals directly to the chromatophores, as well as producing hormones. The skins of cephalopods such as the octopus contain complex units, each consisting of a chromatophore with surrounding muscle and nerve cells. The cephalopod chromatophore has all its pigment grains in
4200-411: The changing colour of the tree trunks on which they rest, from pale and mottled to almost black in polluted areas. This is taken by zoologists as evidence that camouflage is influenced by natural selection , as well as demonstrating that it changes where necessary to resemble the local background. Disruptive patterns use strongly contrasting, non-repeating markings such as spots or stripes to break up
4284-540: The colour-changing abilities, both for camouflage and for signalling , of cephalopods including the octopus, in his Historia animalium : The octopus ... seeks its prey by so changing its colour as to render it like the colour of the stones adjacent to it; it does so also when alarmed . Camouflage has been a topic of interest and research in zoology for well over a century. According to Charles Darwin 's 1859 theory of natural selection , features such as camouflage evolved by providing individual animals with
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#17327980828594368-411: The combination of behaviours and other methods of crypsis involved, young giraffes seek cover, lie down, and keep still, often for hours until their mothers return; their skin pattern blends with the pattern of the vegetation, while the chosen cover and lying position together hide the animals' shadows. The flat-tail horned lizard similarly relies on a combination of methods: it is adapted to lie flat in
4452-504: The countershaded animal nearly invisible against a suitable background. Thayer observed that "Animals are painted by Nature, darkest on those parts which tend to be most lighted by the sky's light, and vice versa ". Accordingly, the principle of countershading is sometimes called Thayer's Law . Countershading is widely used by terrestrial animals , such as gazelles and grasshoppers; marine animals, such as sharks and dolphins ; and birds, such as snipe and dunlin . Countershading
4536-502: The efficacy of disruptive cryptic patterning. Symmetry does not carry a high survival cost for butterflies and moths that their predators views from above on a homogeneous background, such as the bark of a tree. On the other hand, natural selection drives species with variable backgrounds and habitats to move symmetrical patterns away from the centre of the wing and body, disrupting their predators' symmetry recognition. Camouflage can be achieved by different methods, described below. Most of
4620-419: The eye of prey animals on the lookout for predators, and of predators hunting for prey. Most methods of crypsis therefore also require suitable cryptic behaviour, such as lying down and keeping still to avoid being detected, or in the case of stalking predators such as the tiger , moving with extreme stealth, both slowly and quietly, watching its prey for any sign they are aware of its presence. As an example of
4704-400: The features of their bodies, and to match their backgrounds. For example, a caddisfly larva builds a decorated case and lives almost entirely inside it; a decorator crab covers its back with seaweed, sponges, and stones. The nymph of the predatory masked bug uses its hind legs and a ' tarsal fan' to decorate its body with sand or dust. There are two layers of bristles ( trichomes ) over
4788-738: The fish accordingly has crystal stacks with a range of different spacings. A further complication for fish with bodies that are rounded in cross-section is that the mirrors would be ineffective if laid flat on the skin, as they would fail to reflect horizontally. The overall mirror effect is achieved with many small reflectors, all oriented vertically. Silvering is found in other marine animals as well as fish. The cephalopods , including squid, octopus and cuttlefish, have multilayer mirrors made of protein rather than guanine. Some deep sea fishes have very black skin, reflecting under 0.5% of ambient light. This can prevent detection by predators or prey fish which use bioluminescence for illumination. Oneirodes had
4872-482: The genetic components and various ecological pressures that drive crypsis. Camouflage is a soft-tissue feature that is rarely preserved in the fossil record, but rare fossilised skin samples from the Cretaceous period show that some marine reptiles were countershaded. The skins, pigmented with dark-coloured eumelanin , reveal that both leatherback turtles and mosasaurs had dark backs and light bellies. There
4956-436: The genetic components of camouflage in specific organisms illuminates the various ways that crypsis can evolve among lineages. Many cephalopods have the ability to actively camouflage themselves, controlling crypsis through neural activity. For example, the genome of the common cuttlefish includes 16 copies of the reflectin gene, which grants the organism remarkable control over coloration and iridescence. The reflectin gene
5040-534: The genus Eurostopodus . They were moved to the resurrected genus Lyncornis based on the results of a molecular phylogenetic study published in 2010 that found large genetic differences between the great eared nightjar and the other species in Eurostopodus . [REDACTED] This Caprimulgiformes -related article is a stub . You can help Misplaced Pages by expanding it . Eared nightjar Eurostopodus Lyncornis The eared nightjars are
5124-399: The horned lizards which live in open desert is adapted to minimise shadow is supported by the one species which lacks fringe scales, the roundtail horned lizard , which lives in rocky areas and resembles a rock. When this species is threatened, it makes itself look as much like a rock as possible by curving its back, emphasizing its three-dimensional shape. Some species of butterflies, such as
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#17327980828595208-423: The local environment. As there is a lack of evidence for camouflage in the fossil record, studying the evolution of camouflage strategies is very difficult. Furthermore, camouflage traits must be both adaptable (provide a fitness gain in a given environment) and heritable (in other words, the trait must undergo positive selection ). Thus, studying the evolution of camouflage strategies requires an understanding of
5292-534: The method mainly for its efficiency rather than camouflage. Animals such as chameleon , frog, flatfish such as the peacock flounder , squid, octopus and even the isopod idotea balthica actively change their skin patterns and colours using special chromatophore cells to resemble their current background, or, as in most chameleons, for signalling . However, Smith's dwarf chameleon does use active colour change for camouflage. Each chromatophore contains pigment of only one colour. In fish and frogs, colour change
5376-428: The methods help to hide against a background; but mimesis and motion dazzle protect without hiding. Methods may be applied on their own or in combination. Many mechanisms are visual, but some research has explored the use of techniques against olfactory (scent) and acoustic (sound) detection. Methods may also apply to military equipment. Some animals' colours and patterns match a particular natural background. This
5460-466: The microhabitat, the organism has a higher chance of detection. Generalized camouflage allows species to avoid predation over a wide range of habitat backgrounds, but is less effective. The development of generalized or specialized camouflage strategies is highly dependent on the biotic and abiotic composition of the surrounding environment. There are many examples of the tradeoffs between specific and general cryptic patterning. Phestilla melanocrachia ,
5544-538: The night sky, requiring awkward external platforms to support the lamps. The Canadian concept was refined in the American Yehudi lights project, and trialled in aircraft including B-24 Liberators and naval Avengers . The planes were fitted with forward-pointing lamps automatically adjusted to match the brightness of the night sky. This enabled them to approach much closer to a target – within 3,000 yards (2,700 m) – before being seen. Counterillumination
5628-475: The night, and eat their prey on the wing. The flight is buoyant and twisting, and may be interspersed with periods of resting on the ground, a road, or in a tree. These birds drink in flight, gliding low over the water and dipping the beak. 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
5712-485: The night, but roosts some distance away when the female is brooding. If necessary, the female will attempt to distract the intruder away from the eggs, or perform a defence display with spread wings, puffed throat and hissing sounds. The eggs hatch in three to four weeks, and the young can walk soon after hatching. The chicks are fed by both parents. All eared nightjars feed almost entirely on insects caught in flight, typically moths and beetles. They hunt at twilight and in
5796-514: The open desert, relying on stillness, its cryptic coloration, and concealment of its shadow to avoid being noticed by predators. In the ocean, the leafy sea dragon sways mimetically, like the seaweeds amongst which it rests, as if rippled by wind or water currents. Swaying is seen also in some insects, like Macleay's spectre stick insect, Extatosoma tiaratum . The behaviour may be motion crypsis, preventing detection, or motion masquerade, promoting misclassification (as something other than prey), or
5880-442: The open ocean, where there is no background, the principal methods of camouflage are transparencying, silveringing, 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 octopuses , are capable of actively changing their skin pattern and colors , whether for camouflage or for signalling. It
5964-408: The outlines of an animal or military vehicle, or to conceal telltale features, especially by masking the eyes , as in the common frog . Disruptive patterns may use more than one method to defeat visual systems such as edge detection . Predators like the leopard use disruptive camouflage to help them approach prey, while potential prey use it to avoid detection by predators. Disruptive patterning
6048-474: The same time in Australia , zoologist William John Dakin advised soldiers to copy animals' methods, using their instincts for wartime camouflage. The term countershading has a second meaning unrelated to "Thayer's Law". It is that the upper and undersides of animals such as sharks, and of some military aircraft, are different colours to match the different backgrounds when seen from above or from below. Here
6132-467: The shrimps it associates with, Pseudopalaemon gouldingi , are so transparent as to be "almost invisible"; further, these species appear to select whether to be transparent or more conventionally mottled (disruptively patterned) according to the local background in the environment. Where transparency cannot be achieved, it can be imitated effectively by silvering to make an animal's body highly reflective. At medium depths at sea, light comes from above, so
6216-477: The sides of a tank. The Peltier plate panels are heated and cooled to match either the vehicle's surroundings (crypsis), or an object such as a car (mimesis), when viewed in infrared. Countershading uses graded colour to counteract the effect of self-shadowing, creating an illusion of flatness. Self-shadowing makes an animal appear darker below than on top, grading from light to dark; countershading 'paints in' tones which are darkest on top, lightest below, making
6300-462: The speckled wood, Pararge aegeria , minimise their shadows when perched by closing the wings over their backs, aligning their bodies with the sun, and tilting to one side towards the sun, so that the shadow becomes a thin inconspicuous line rather than a broad patch. Similarly, some ground-nesting birds, including the European nightjar , select a resting position facing the sun. Eliminating shadow
6384-722: The summer to white in the winter; the Arctic fox is the only species in the dog family to do so. However, Arctic hares which live in the far north of Canada , where summer is very short, remain white year-round. The principle of varying coloration either rapidly or with the changing seasons has military applications. Active camouflage could in theory make use of both dynamic colour change and counterillumination. Simple methods such as changing uniforms and repainting vehicles for winter have been in use since World War II. In 2011, BAE Systems announced their Adaptiv infrared camouflage technology. It uses about 1,000 hexagonal panels to cover
6468-835: The target's speed, range, and heading. During and after the Second World War , a variety of camouflage schemes were used for aircraft and for ground vehicles in different theatres of war. The use of radar since the mid-20th century has largely made camouflage for fixed-wing military aircraft obsolete. Non-military use of camouflage includes making cell telephone towers less obtrusive and helping hunters to approach wary game animals. Patterns derived from military camouflage are frequently used in fashion clothing, exploiting their strong designs and sometimes their symbolism. Camouflage themes recur in modern art, and both figuratively and literally in science fiction and works of literature. In ancient Greece, Aristotle (384–322 BC) commented on
6552-470: The theory to a fantastic extreme in an endeavour to make it cover almost every type of coloration in the animal kingdom." Cott built on Thayer's discoveries, developing a comprehensive view of camouflage based on "maximum disruptive contrast", countershading and hundreds of examples. The book explained how disruptive camouflage worked, using streaks of boldly contrasting colour, paradoxically making objects less visible by breaking up their outlines. While Cott
6636-410: The two Australian species (spotted and white-throated nightjars) are partial migrants . These are birds of open woodland or forest clearings and edges. No nest is built, the single white egg is laid directly on to the ground or leaf litter . The female incubates the egg during the day, relying mainly on the excellent camouflage of the plumage to avoid predators. The male takes over incubation during
6720-508: The wavelength of visible light. A familiar example is the transparency of the lens of the vertebrate eye , which is made of the protein crystallin , and the vertebrate cornea which is made of the protein collagen . Other structures cannot be made transparent, notably the retinas or equivalent light-absorbing structures of eyes – they must absorb light to be able to function. The camera -type eye of vertebrates and cephalopods must be completely opaque. Finally, some structures are visible for
6804-415: The wing area, making them powerful and agile in flight. An important difference from typical nightjars is the lack of bristles around the beak. They are nocturnal and have a reflective tapetum lucidum at the back of the eye. The beaks are small, but these birds have a very large gape for catching insects in flight. The feet and legs are small and weak, and the toes are partly webbed. The middle toe's claw has
6888-682: Was identified as a principle of military camouflage during the Second World War . Many prey animals have conspicuous high-contrast markings which paradoxically attract the predator's gaze. These distractive markings may serve as camouflage by distracting the predator's attention from recognising the prey as a whole, for example by keeping the predator from identifying the prey's outline. Experimentally, search times for blue tits increased when artificial prey had distractive markings. Some animals actively seek to hide by decorating themselves with materials such as twigs, sand, or pieces of shell from their environment, to break up their outlines, to conceal
6972-464: Was made obsolete by radar , and neither diffused lighting camouflage nor Yehudi lights entered active service. Many marine animals that float near the surface are highly transparent , giving them almost perfect camouflage. However, transparency is difficult for bodies made of materials that have different refractive indices from seawater. Some marine animals such as jellyfish have gelatinous bodies, composed mainly of water; their thick mesogloea
7056-498: Was more systematic and balanced in his view than Thayer, and did include some experimental evidence on the effectiveness of camouflage, his 500-page textbook was, like Thayer's, mainly a natural history narrative which illustrated theories with examples. Experimental evidence that camouflage helps prey avoid being detected by predators was first provided in 2016, when ground-nesting birds ( plovers and coursers ) were shown to survive according to how well their egg contrast matched
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