lizard

The common iguana lives mainly in trees but is an excellent swimmer. It has a characteristic crest of comblike spines running down the length of its back. Young animals are bright green, becoming darker with age.

The frilled lizard of North Australia and New Guinea has a rufflike collar of skin - up to 25 cm/10 in across - around its neck. The collar normally lies flat but, if alarmed, the lizard raises the brightly coloured collar and opens its mouth to intimidate an enemy.

Reptile generally distinguishable from snakes, which belong to the same order, by having four legs, moveable eyelids, eardrums, and a fleshy tongue, although some lizards are legless and snakelike in appearance. There are over 3,000 species of lizard worldwide. (Suborder Lacertilia, order Squamata.)

Like other reptiles, lizards are abundant in the tropics, although some species live as far north as the Arctic circle. There are about 20 families of lizards, including geckos, chameleons, skinks, monitors, agamas, and iguanas. The common or viviparous lizard (Lacerta vivipara), about 15 cm/6 in long, is found throughout Europe; in the far north, it hibernates through the long winter. Like many other species, it can shed its tail as a defence, later regrowing it. The frilled lizard (Chlamydosaurus kingi) of Australia has an erectile collar to frighten its enemies. There are two poisonous species of lizard, the Mexican bearded lizard and the gila monster. A new lizard species discovered in the West Indies in 2001, Sphaerodactylus ariasae, measures only 1.6 cm/0.6 in. (For flying lizard see flying dragon.)