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 breaking up their outlines with strong contrasts. Fish like "Heniochus macrolepidotus" have similar bands of colour that extend into fins projecting far from the body, distracting attention from the true shape of the fish. Some fish which mimic seaweeds such as the frogfishes "Antennarius marmoratus" and "Pterophryne tumida" have elaborate projections and spines which are combined with complex disruptive coloration. These have the effect of destroying the signature "fish" outline of these animals, as well as helping them to appear as pieces of algae. A variety of marine animals possess active camouflage through their ability to change colour rapidly. Several