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
Self-decoration camouflage materials including moulted cuticle and their own droppings, which appears to serve both to camouflage the larvae and to repel predators. Larvae of species that eat aphids decorate themselves with the waxy material produced by the aphids; larvae decorated like this are ignored by ants which farm the aphids, whereas the ants eject undecorated larvae, making this a wolf in sheep's clothing strategy of aggressive mimicry. The strategy has been used by traditional human hunters, such as when Australian aborigines dressed in emu skins and adopted emu-like postures to hunt these birds. Snipers, working alone, rely heavily on effective camouflage.