CHAMELEON

any member of the reptile family Chamaeleontidae, a group of Old World, primarily tree-dwelling lizards characterized chiefly by their ability to change body colour; by zygodactylous toes (i.e., fused into opposed bundles of two and three); acrodont dentition (i.e., teeth attached to the jaw edge); and a long, slender, extensile tongue. The name is also applied to the false chameleon, or anole (q.v.), a New World lizard of the family Iguanidae. Two genera of true chameleons have been described: Brookesia (19 species) and Chamaeleo (70 species). About half the species occur only in Madagascar; the others occur mostly in Africa south of the Sahara. Two species occur in western Asia, one in southern India and Sri Lanka (Ceylon), and one (the European chameleon, Chamaeleo chamaeleon) is found from the Near East westward across northern Africa and into southern Spain. Most chameleons are 1725 centimetres (7 10 inches) long; the longest grows to 60 cm. The body is flattened from side to side, and the tail is sometimes curled. The bulged eyes are independently movable. In certain chameleons the head is helmet shaped. Some species have conspicuous head ornamentation that may include as many as three long horns projecting forward. Such features are either better or exclusively developed in males. At least some are related to territorial defense: a dominant male responds to an invading male by expanding the body, puffing out the throat, and elevating or waving special head flaps. If this display fails to intimidate an intruder, the defender charges and snaps his jaws. Each species is capable of undergoing a particular range of colour change. The mechanism involves dispersion or concentration of pigment in cells containing pigment granules (melanophore cells) that are under the control of the autonomic nervous system. Many can assume green, yellow, cream, or dark brown, frequently with lighter or darker spots on the ground colour. Colour change is determined by such environmental factors as light and temperature as well as by emotions such as fright and those associated with victory or defeat in battle with another chameleon. It is a popular misconception that the chameleon changes its colour to match that of the background. Insects are the main diet, but large chameleons also eat birds. Most species are egg layers and descend from their shrub or tree to bury 2 to 40 eggs in the soil or rotting logs. Incubation lasts about three months. A few south African species bear live young.