Chameleon turquoise, and purple. Chameleon skin has a superficial layer which contains pigments, and under the layer are cells with guanine crystals. Chameleons change colour by changing the space between the guanine crystals, which changes the wavelength of light reflected off the crystals which changes the colour of the skin. Colour change in chameleons has functions in camouflage, but most commonly in social signaling and in reactions to temperature and other conditions. The relative importance of these functions varies with the circumstances, as well as the species. Colour change signals a chameleon's physiological condition and intentions to other chameleons. Chameleons tend
Underwater camouflage in a vertical position with its head pointing downwards, and behaves in a way that perfectly resembles the movement of a piece of seaweed: moving back and forth in the surge, as if it was inanimate. Self-decoration is employed by animals in different groups, including decorator crabs, which attach materials from their environment, as well as living organisms, to camouflage themselves. For example, the Japanese hermit crab, "Eupagurus constans", has the hydroid "Hydractinia sodalis" growing all over the shell that it lives in. Another hermit crab, "Eupagurus cuanensis", has the aposematic orange sponge "Suberites domuncula" which is bitter-tasting and not