Iguana is a genus of lizard native to tropical areas of Central and South America and the Caribbean. The genus was first described by Austrian naturalist Josephus Nicolaus Laurenti in his book Specimen Medicum, Exhibens Synopsin Reptilium Emendatam cum Experimentis circa Venena in 1768. The genus Iguana includes two species: the Green Iguana, which is widespread throughout its range and a popular pet, and the Lesser Antillean Iguana, which is endemic to the Lesser Antilles and endangered due to habitat destruction.
The two species of lizard within the genus Iguana possess a dewlap, a row of spines running down their back to their tail, and a third "eye" on their head. This eye is known as the parietal eye, visible as a pale scale on the top of the head. Behind their neck are small scales which resemble spikes, known as tuberculate scales. These scales may be a variety of colors and are not always visible from close distances. They have a large round scale on their cheek known as a subtympanic shield.
Iguanas have excellent vision and are able to see shapes, shadows, colors, and movement at long distances. Iguanas use their eyes to navigate through crowded forests, as well as for finding food. They use visual signals to communicate with other members of the same species.
The tympanum is the iguana's ear drum, and is located right above the subtympanic shield and behind the eye. Iguanas are often hard to spot, as they tend to blend into their surroundings. The color green helps as a mode of hiding from larger predators.
Green iguana at St. Thomas
Another green iguana (Iguana iguana)
A lesser Antillean iguana in the wild in Dominica.