Aposematism

(also warning coloration and form), one of the types of protective coloration and form in animals. Aposematic coloration, which contrasts with the animal’s background, is demonstrated suddenly in response to danger and is usually combined with a threatening pose and sounds.

The back wings of certain moths of the family Sphingidae and the genus Noctuidae, as well as cicadas, locusts, and mantises, have eyelike spots or bright bands. Normally these insects are not noticeable, owing to cryptic coloration. When an enemy approaches, however, they open their back wings and unexpectedly reveal their bright coloring, which frightens off the predator. Caterpillars of the family Sphingidae assume a threatening pose, raising the front portion of the body slightly and inflating the thorax, on which eyelike spots protrude in some species. Octopuses, agamas, and chameleons assume a threatening pose and acquire vivid coloration; many reptiles also hiss. The death’s-head moth emits a sharp squeak by releasing air from its foregut.

Aposematism protects animals from predators and gives them an advantage in the struggle for life.