Chameleon, (family Chamaeleonidae), any of a group of primarily arboreal (tree-dwelling) Old World lizards best known for their ability to change body colour. Other characteristics of chameleons include zygodactylous feet (with toes fused into opposed bundles of two and three), acrodont dentition (with the teeth attached to the edge of the jaw), eyes that move independently, atrophied venom glands that produce harmless trace amounts of venom, and a long, slender projectile tongue.
The longest chameleon in the world is Parson’s chameleon (Calumma parsonii), which may grow up to 69.5 cm (about 27 inches) long. On the other hand, the world’s shortest chameleon, the male nano-chameleon (Brookesia nana), can be as small as 21.6 mm (about 0.9 inch) long. Most chameleons, however, are 17–25 cm (7–10 inches) long. The body is laterally compressed, the tail is sometimes curled, and the bulged eyes move independently of one another. Also, some chameleons possess helmet-shaped heads.
