protective coloration

protective coloration coloration or color pattern of an animal that affords it protection from observation either by its predators or by its prey. The most widespread form of protective coloration is called cryptic resemblance, in which various effects that supplement the similarity of color between the animal and its surroundings enable the creature to blend into the background of its habitat. Disruptive coloration, or irregular patches of contrasting colors, serve to distract the observer's eye from the outline of the animal. Thus the stripes of the tiger and the zebra make detection among the jungle grasses more difficult, whereas the leopard's spots are more suited to the mottled light and shade of the low branches from which it drops onto its prey. Many other creatures (e.g., frogs, lizards, and snakes) are dappled, barred, speckled, mottled, or otherwise distinctively marked or colored so that they blend with sand, water, snow, or specific vegetation, depending on their natural habitat. The pigmentation of some animals (e.g., the chameleon and the flounder) changes to resemble different backgrounds. In countershading, the upper surface of the animal is darker than the undersurface and produces the illusion of flatness. Countershading also aids many fish and birds by blending them with the sky or with the upper water surface when viewed from below and with the land or the sea bottom when viewed from above. Some animals undergo a seasonal variation in color: The stoat and the caribou turn from brown in summer to white in winter (when the stoat is known as ermine). A second type of protective coloration, in animals whose coloration or markings distinctly contrast with their habitat, serves as a warning device either to its predators (e.g., the skunk's stripe and the brilliant colors of many venomous snakes and distasteful insects) or to other members of their species in the vicinity (as the white tail patches of the pronghorn and the jack rabbit that are flashed on approaching danger). The adaptation of an organism's appearance to resemble that of another organism that is repugnant or dangerous to a potential predator is called mimicry . Coloration may thus be categorized as concealing, revealing, or deceiving. Although these devices are not invariably successful, they do increase the statistical chance for survival of the species. The most widely accepted explanation of the phenomenon of protective coloration is Darwin's theory of natural selection .

Bibliography: See R. A. Carr, Protective Coloration and Mimicry (1972); M. Edmunds, Defence in Animals (1974).