Such coloration is found among animals that have natural defenses that they use to deter or fend off predators. These defenses can take many forms. Many of these animals are brightly colored, presumably as a warning to potential aggressors. Behavioral biologists believe that predatory animals learn to associate such brightly colored animals with unpleasant or painful experiences and therefore are likely to pass them up as potential prey in favor of a more drab animal. Common warning colors are red, black, and yellow.
Some organisms can change their color from drab to bright when threatened.
The octopus, for example, turns white when agitated and red when it is suddenly frightened. Certain chameleons, usually camouflaged, display a brightly colored throat sac, or dewlap, as a warning signal to invaders. Fin Other forms of protective coloration. Some animals are colored in such a way that they draw attention to themselves only when they are in motion. Certain birds have light-colored feathers that are visible only during flight.