Iguana is a genus of herbivorous lizards native to tropical areas of Mexico, Central America, several islands in Polynesia such as Fiji and Tonga, and the Caribbean. The genus was first described in 1768 by Austrian naturalist Josephus Nicolaus Laurenti in his book Specimen Medicum, Exhibens Synopsin Reptilium Emendatam cum Experimentis circa Venena. Two species are included in the genus Iguana: the green iguana, which is widespread throughout its range and a popular pet, and the Lesser Antillean iguana, which is native to the Lesser Antilles and endangered due to habitat destruction.
Iguana can range from 5 to 6 feet (1.5 to 1.8 m) including their tail. The two species of lizard within the genus Iguana possess a dewlap, a row of spines running down their backs to their tails, and a third "eye" on their heads. This eye is known as the parietal eye, visible as a pale scale on the top of the head. Behind their necks are small scales which resemble spokes, 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 cheeks known as a subtympanic shield.
Iguanas have great vision and can 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, the iguana's ear drum, is located above the subtympanic shield and behind the eye. Iguanas are often hard to spot, as they tend to blend into their surroundings. Their scale colors are a mode of hiding from larger predators.