It might sound like something straight out of a sci-fi movie, but iguanas actually have three eyes! Their third eye, which resembles a scale on the top of their heads, is called the parietal eye. This organ is sensitive to changes in illumination, and scientists believe the lizards use it as a sort of sun-calibrated compass to steer by the sun.

Eggs are laid in a burrow in a warm, sunny area. The mother covers the eggs and then walks away. Once they hatch, the baby iguanas are completely on their own for the three years it takes to fully mature because their mother never returns.

It isn't hard to see why a group of iguanas is called a mess. They often lie intertwined in large groups, and it can be difficult to see where one iguana ends and another begins.

The black spiny-tailed iguana (Ctenosaura similis) is recognized as the fastest-running species of lizard, with maximum sprint speeds of just under 22 miles per hour (35 km/h).

In Central and South America, green iguanas are still used as a source of meat and are often referred to as gallina de palo or "chicken of the trees" because they are said to taste like chicken.

The marine iguana (Amblyrhynchus cristatus), also known as the sea iguana or saltwater iguana, is found only on the Galápagos Islands of Ecuador. Unique among modern lizards, it is a marine reptile that has the ability to forage in the sea for algae, which makes up almost all of its diet. Large males are able to dive to find this food source, while females and smaller males feed during low tide in the intertidal zone.

The longest iguana is the green iguana, which can grow up to two meters (6 ft) long from nose to tail. However, the heaviest iguana is the blue iguana, which can weigh a hefty 15 kilograms (30 lbs).

While they may often be found in trees, these animals are well-known burrowers. In Palm Beach, Florida, where green iguanas are considered an invasive species, water control structures had to be hardened after iguanas dug burrows into the soft dirt around an aging dam, causing city officials to spend $1.8 million in emergency repairs.

On Panama's Slothia Island, iguanas have been observed sharing a nesting area with an American crocodile (Crocodylus acutus) over three successive nesting seasons. Although it has been proposed that the iguanas did this so that their nests would be guarded by the crocodile, it seems more likely that the two species were simply brought together by similar nesting requirements. Neither species seemed to benefit from the proximity as the crocodile both interrupted iguana nesting activities and killed and ate some of the iguanas, and the iguanas sometimes dug up the crocodile's eggs.

The tails of iguanas break off easily as a defense mechanism. The broken-off section wriggles rapidly and distracts predators as the lizard scurries for safety.