The common green iguana is one species within one genus of a family of lizards found mostly in the New World. This green iguana and the other typical iguanas are tropical and semi-tropical and active during daylight hours (diurnal). Their eyes have round pupils and well developed lids. Their tongues are short, thick and only slightly notched, as contrasted to the long forked tongue of, for instance, the monitor lizards. It lays eggs, in common with most other iguanids (oviparous). Only a few give birth to living young (viviparous). They are frequently but not always brightly colored; they often have spines, frills or crests, and many can distend their throats. They can alter their color somewhat, some species more than others. Some may favor trees (arboreal) and others favor the land (terrestrial). Two are from the Galapagos Islands, and one of these is semi-marine, eats seaweed and would probably rather die than climb a tree.
For a beginning herpetologist or hobbyist pet keeper, the best iguana is the common green iguana – scientifically: Iguana iguana iguana. If you don’t go out of your way when you choose a pet in a pet shop, this is what you probably will get. Good. The only other iguanas that resemble it are Iguana iguana delicatissima which lacks the circular shields found below the eardrums of Iguana iguana iguana, and Iguana iguana rhinolopha which has a slight protuberance at the snout. So there you have it – genus Iguana, species iguana, and subspecies perhaps iguana or delicatissima or rhinolopha.