'' lizard showing
camouflage methods including background matching,
disruptive coloration, reduction of shadow, and cryptic behavior in
Bandipur National Park Methods of crypsis include (visual) camouflage,
nocturnality, and subterranean lifestyle. Camouflage can be achieved by a
wide variety of methods, from
disruptive coloration to
transparency and some forms of
mimicry, even in habitats like the open sea where there is no background. As a strategy, crypsis is used by
predators against prey and by
prey against predators. and
pheromone production. Crypsis can in principle involve visual, olfactory, or auditory camouflage.
Visual allows animals like this
disruptively-patterned spider to capture prey more easily. Many animals have evolved so that they visually resemble their surroundings by using any of the
many 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, like
the tawny dragon lizard, may resemble rocks, sand, twigs, leaves, and even bird droppings (
mimesis). Other methods including transparency and silvering are widely used
by marine animals. Some animals change color in changing environments seasonally, as in
ermine and
snowshoe hare, or far more rapidly with
chromatophores in their integuments, as in
chameleon and
cephalopods such as
squid.
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 artist
Abbott 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. The
decorator 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 as
sea anemones or noxious plants, benefiting from
aposematism as well as or instead of crypsis.
Olfactory Some animals, in both terrestrial and aquatic environments, appear to camouflage their odor, which might otherwise attract predators. Numerous arthropods, both insects and spiders,
mimic ants, whether to avoid predation, to hunt ants, or (as in the
large blue butterfly caterpillar) to trick the ants into feeding them.
Pirate perch (
Aphredoderus sayanus) may exhibit chemical crypsis, making them undetectable to frogs and insects colonizing ponds. Trained dogs and meerkats, both scent-oriented predators, have been shown to have difficulty detecting
puff adders, whose strategy of
ambushing prey necessitates concealment from both predators and prey.
Auditory Some insects, notably some
Noctuid moths, (such as the
large yellow underwing), and some
tiger moths, (such as the
garden tiger), have been supposed to defend themselves against predation by
echolocating 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"). or at least performing as acoustic
mimics of unpalatable moths. 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. == References ==