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 all flounders, Peacock flounders, "Bothus mancus", have excellent adaptive camouflage. They use cryptic coloration to avoid being detected by both prey and predators. Whenever possible rather than swim, they crawl on their fins along the bottom while constantly changing colours and patterns to match their background. In a study, some flounders demonstrated the ability to change pattern in eight seconds. They were able to match the pattern of checkerboards that they were placed on. Changing pattern is an extremely complex process involving the flounder's vision and hormones. If one of the fish's eyes is damaged, or covered by the sand,