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Inecology,crypsis is the ability of an animalor a plant[1] to avoid observation or detection by other animals. It may be part of apredation strategy or anantipredator adaptation. Methods includecamouflage,nocturnality,subterranean lifestyle andmimicry. Crypsis can involve visual, olfactory (withpheromones) or auditory concealment. When it is visual, the termcryptic coloration, effectively a synonym for animal camouflage, is sometimes used, but many differentmethods of camouflage are employed in nature.
There is a strongevolutionary pressure for prey animals to avoid predators through camouflage, and for predators to be able to detect camouflaged prey. There can be a self-perpetuatingcoevolution, in the shape of anevolutionary arms race, between the perceptive abilities of animals attempting to detect the cryptic animal and the cryptic characteristics of the hiding species.[2]
Methods of crypsis include (visual) camouflage,nocturnality, and subterranean lifestyle. Camouflage can be achieved by awide variety of methods, fromdisruptive coloration totransparency and some forms ofmimicry, even in habitats like the open sea where there is no background.[3][4]
As a strategy, crypsis is used bypredators against prey and byprey against predators.[3]
Crypsis also applies toeggs[5] andpheromone production.[6] Crypsis can in principle involve visual, olfactory, or auditory camouflage.[7]
Many animals have evolved so that they visually resemble their surroundings by using any of themany methods of natural camouflage that may match the color and texture of the surroundings (cryptic coloration) and/or break up the visual outline of the animal itself (disruptive coloration). Such animals, likethe tawny dragon lizard, may resemble rocks, sand, twigs, leaves, and even bird droppings (mimesis). Other methods including transparency and silvering are widely usedby marine animals.[8]
Some animals change color in changing environments seasonally, as inermine andsnowshoe hare, or far more rapidly withchromatophores in their integuments, as inchameleon andcephalopods such assquid.
Countershading, the use of different colors on upper and lower surfaces in graduating tones from a light belly to a darker back, is common in the sea and on land. It is sometimes called Thayer's law, after the American artistAbbott Handerson Thayer, who published a paper on the form in 1896 that explained that countershading paints out shadows to make solid objects appear flat, reversing the way that artists use paint to make flat paintings contain solid objects. Where the background is brighter than is possible even with white pigment,counter-illumination in marine animals, such as squid, can use light to match the background.
Some animals actively camouflage themselves with local materials. Thedecorator crabs attach plants, animals, small stones, or shell fragments to their carapaces to provide camouflage that matches the local environment. Some species preferentially select stinging animals such assea anemones or noxious plants, benefiting fromaposematism as well as or instead of crypsis.[9]
Some animals, in both terrestrial and aquatic environments, appear to camouflage their odor, which might otherwise attract predators.[10] Numerous arthropods, both insects and spiders,mimic ants, whether to avoid predation, to hunt ants, or (as in thelarge blue butterfly caterpillar) to trick the ants into feeding them.[11]Pirate perch (Aphredoderus sayanus) may exhibit chemical crypsis, making them undetectable to frogs and insects colonizing ponds.[12] Trained dogs and meerkats, both scent-oriented predators, have been shown to have difficulty detectingpuff adders, whose strategy ofambushing prey necessitates concealment from both predators and prey.[13]
Some insects, notably someNoctuid moths, (such as thelarge yellow underwing), and sometiger moths, (such as thegarden tiger), have been supposed to defend themselves against predation byecholocating bats, both by passively absorbing sound with soft, fur-like body coverings and by actively creating sounds to mimic echoes from other locations or objects. The active strategy was described as a "phantom echo" that might therefore represent "auditory crypsis" with alternative theories about interfering with the bats' echolocation ("jamming").[14][15]Subsequent research has provided evidence for only two functions of moth sounds, neither of which involve "auditory crypsis". Tiger moth species appear to cluster into two distinct groups. One type produces sounds as acousticaposematism, warning the bats that the moths are unpalatable,[16] or at least performing as acousticmimics of unpalatable moths.[17] The other type uses sonar jamming. In the latter type of moth, detailed analyses failed to support a "phantom echo" mechanism underlying sonar jamming, but instead pointed towards echo interference.[18]
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