Iguana - biology.

Iguana - biology. Iguana, common name for the larger lizards of the iguana family. These reptiles are known for their impressive courting and defensive displays, such as raising their bodies and bobbing their heads vigorously. They are found mostly in the Americas and, outside the western hemisphere, only in Madagascar, Fiji, and Tonga. Lizards of the iguana family are similar to the agamine lizards of Eurasia, except that their teeth are solidly joined to the inner edge of the jaw instead of to the margin of the jawbone. Iguanas are diurnal. They have distinct eyelids, large external eardrums, and often, conspicuous throat pouches, or dewlaps. Each limb has five free toes ending in sharp claws. Unlike most other lizards, iguanas are vegetarians. Their habitats vary: Some live in trees, some near water, and some in arid habitats. Recent studies show that members of the iguana family have venom-secreting glands in their mouths and can deliver low levels of venom in their bites. The green iguana is abundant throughout tropical America, living in trees often overhanging water. Adult males are grayish or orangish, with dark bars on the sides of the body and broad black circles ringing the tail; the females are generally greenish. Green iguanas grow to about 1.8 m (about 6 feet). They have a row of leathery spines along the back from the neck to the tail. The long, powerful tail is usually slightly flattened. Both the flesh and eggs of this species are valued as food. The rhinoceros iguana, a terrestrial species found in Haiti and Puerto Rico, gets its name from the three horns on its forehead. Two iguanas are confined to the Galápagos Islands, including the marine iguana, the only lizard that regularly inhabits the sea. It lives on beaches and enters the water to forage on seaweed. The monitor lizard is sometimes called an iguana (see Monitor). Scientific classification: Iguanas belong to the family Iguanidae. The green iguana is classified as Iguana iguana, the rhinoceros iguana as Cyclura cornuta, and the marine iguana as Amblyrhynchus cristatus. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.