The name iguana usually refers only to the members of the subfamily iguana. The best-known species is the common green iguana, which occurs from Mexico southward to Brazil. Males of this species reach a maximum length of over 2 meters (6.6 feet) and 6 kg (13.2 pounds). It is often seen basking in the sun on the branches of trees overhanging water, into which it will plunge if disturbed. The common iguana is green with dark bands that form rings on the tail; females are grayish green and about half the weight of males. Iguanas also possess atrophied venom glands that produce a weak, harmless venom.
Food of the common iguana consists largely of leaves, buds, flowers, and fruits of fig trees (genus Ficus), although many other trees are also fed upon. Whereas this lizard has a well-developed digestive system housing bacteria that ferment plant material, it also eats invertebrates when young and has been known to eat small birds and mammals.
During the rainy season, males become territorial, and mating pairs are established. At the end of the rainy season, eggs are fertilized and then laid in clutches of 30 or 50 in the ground during the early dry season. After 70–105 days, the 7.6-cm- (3-inch-) long hatchlings emerge. During this time, eggs and young are vulnerable to predators such as omnivores. Adult iguanas have been used as food by humans for thousands of years and are threatened by hunting and habitat loss. In rural areas, they are a major source of protein.
Slow and Steady
The iguanas aren’t very active animals. Most of the time, these tree-dwellers don’t move much, blending into the forest canopy to avoid being noticed by predators. When they do move, they appear sluggish, but they’re capable of picking up the pace if pursued.
Triple Threat
The iguanas have a so-called “third eye” on the top of their heads. Known as the parietal eye, it looks like a pale scale and can’t discern shapes or color—but does sense light and movement, helping iguanas anticipate predatory birds from above.
Thanks to their regular eyes, iguanas also have outstanding vision and can see color and movement at large distances.
The iguana rests in a grassy area with a few dried leaves in the foreground.
View of an iguana's spiny head and neck and clawed front leg as it rests on a rock.
This iguana is a resident of the Virgin Islands.
Don’t Call Them Cold-Blooded
Their blood’s not cold, but iguanas depend on their environment to maintain their body temperature. Several anatomical features help them regulate their body heat, including their distinctive dewlaps, the large flaps of skin under their chin. At lower body temperatures, the lizards’ skin is darker to absorb more sunlight. As the iguana warms up, their skin grows paler to better reflect the rays.
Group Nesting
Female iguanas can lay dozens of eggs over the course of three days, into burrows up to 3 feet deep. When nesting sites are few and far between, females will band together to share.
Flight or Fight
Iguanas are great swimmers and will try to escape a predator by diving into a body of water, then using its tail to propel itself away. If flight’s not an option, an iguana will threaten with its dewlap and bob its head aggressively, whipping its long tail, which is studded with spines. Like some other lizards, if caught by the tail an iguana can “drop” it to make its getaway, then regrow it at a later time.
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