Chameleon, a tree-dwelling lizard having the ability to change color and to move each eye independently. The color change is involuntary, contrary to common belief, and is brought about by light, temperature, and nervous stimulation such as anger or fear. It is not related to the color of the substance on which the chameleon happens to be. Under ordinary conditions, the rough skin of the chameleon is a dull brownish-green. Under stresses of fear or anger, the color changes to a vivid green; it turns brown or yellowish-gray in response to hunger, low temperatures, and strong sunlight. The males of some species may display a brilliant red dewlap (a loose fold of skin under the throat) during courtship or in combat.