Iguana

Iguana is a genus of reptiles, although the name can refer to any of the species belonging to the family Iguanidae. They are large terrestrial reptiles although some have adapted to life in the water (Marine iguana).

Iguanas are commonly used as pets, especially the green iguana that can grow to six feet long. They can be great pets if treated well and can even be walked on leashes. The average lifespan of these pet iguanas is usually around 20 years.

Iguanas can be found in the neotropical rainforest, at lower altitudes by a lake or river. Most of their time is spent in the higher forest canopy, 40-50 feet above ground.

Anatomy
The different species of iguana can vary slightly in their anatomy, but are generally similar. A few of the things they have in common are: their two eyes on either side of the head, nostrils, mouth, scales covering the body, along with the normal parts of the body that all lizards have. Iguanas have many sharp, jagged teeth to shred plants and any animals they might eat. Iguanas also have a parietal eye to detect overhead predators by sensing light and dark. Femoral pores along the hind legs can indicate when the iguana is in breeding season because the pores have waxy plugs protruding from them. Male iguanas have hemipenes for breeding. Most species of iguana generally only vary by size and color. 

Reproduction
Green iguanas breed during the dry season when the nuptial (marital) period and fecundation correspond with the start of the season. About a month later, the females lay 14 to 76 eggs weighing around 9-14 g in burrows made in communal nesting sites. At the end of the three-month incubation period, the newly hatched iguanas surface from the nest. This is timed to match with the arrival of the rainy season. Brown iguana lay an average of 43 small eggs, usually weighing 4-8 g. Peak reproduction in the wild is said to be around five to eight nesting seasons. 

Ecology
Iguanas can be thought of as an invasive species along the gulf coast of Florida, and particularly on Gasparilla Island. They often destroy gardens, hide in the attics of houses, and roam around beaches. They add to natural habitat loss, help spread salmonella, and could possibly be accountable for the decline of the gopher tortoise. This happened because of a combination of intentionally released and escaped iguanas which survived and then succeed in their new habitat.

Many iguanas are a necessary part of their habitat. As infants, they are food for many predators. As adults, they eat fruit and may spread seeds in the habitat. The adult iguanas are not at risk from very many predators because they can defend themselves with their sharp teeth and strong tails. If they do make it to adulthood, they can be expected to live for ten or fifteen years and sometimes more.

The one predator the iguana is no match for is humans. Native people sometimes refer to the green iguanas as “the chicken of the trees”. Green iguanas are harvested for their eggs, skin, and meat. Wild females are captured and then their eggs are gathered for food, and to supply stores with babies for the pet trade. Small-scale hunting is no threat to iguana populations, but large-scale harvesting, mainly to give to the pet trade, is. The biggest threat to the wild existence of iguanas is habitat loss. As more rain forests disappear, so do many iguanas. Although they are not listed as endangered or threatened, they are certainly at risk, along with all the other inhabitants of these forests. 

Diet
Iguanas are often thought of as omnivores, but usually eat plants and fruits. Some iguanas eat insects, eggs, and other small vertebrates. This does not apply to iguanas in captivity because, although they will eat animal food if given some, the animal protein will often result in severe health problems. 

Related References

 * Iguana From Wikipedia, the free encyclopedia
 * Iguanas in the Wild Green Iguana Society
 * Lizards and snakes FAO Corporate Document Repository