Length: 3.9 inches (10 centimeters) to 6.6 feet (2 meters), depending on species
Incubation of eggs: 65 to115 days, depending on species
Number of eggs: average 20 to 40 per clutch
Size at hatching: 7.9 inches (20 centimeters)
Age of maturity: 3 years
Conservation status: many are endangered, such as the Anegada Island iguana Cyclura pinguis and the Jamaican iguana Cyclura collei
Many of us think lizards live only in deserts,
yet the marine iguanas of the Galápagos Islands (off
the coast of Ecuador) are excellent swimmers.
Some iguanas enjoy living in trees, such as the green iguanas of Central and South America. Because they are farmed for food there, these iguanas are called gallina de palo, or “chicken of the tree.”
In the Animal Kingdom, males often have the brightest colors, but not among green iguanas. Here, the males are a dull green color with an orange chest, females are brighter, and the juveniles are the brightest green.
A male iguana's long, erect spines and extended dewlap, which make his head appear larger, are features that attract females. Battered and chewed spines indicate a male with a low position in the mating hierarchy.
The San Diego Zoo was the first zoo in the United States to hatch an Anegada Island iguana.
Outside of Fiji, the San Diego Zoo has the largest and most successful colony of endangered fijian banded iguanas Brachylophus bulabula. We have reproduced more than 100 offspring since 1965.
As of August 2012, 20 Grand Cayman iguanas have hatched at our facilities.
Listen to an iguana!
Range: southeastern Canada to Central and South
America, the Galápagos
Islands, some Caribbean islands (such as Cuba, Jamaica, and
the Anegadas), Fiji in the South Pacific, and Madagascar,
off the east coast of Africa.
The iguana family includes some of the largest lizards found in the Americas, with their whiplike tails making up about half of that length. Like other reptiles, iguanas are cold-blooded, egg-laying animals with an excellent ability to adapt to their environment. Species of iguanas vary greatly in size, color, behavior, and their endangered status in the wild. Some species, like the green iguana Iguana iguana, are quite common; other species, like the Fijian banded iguana Brachylophus bulabula, are endangered.
The adaptive nature of the iguana
Different species of iguanas look and act so differently, you might not recognize them as members of the same family. While some iguanas have colors that are vivid and bright, others are rather dull. Because iguanas can be found in a variety of habitats, each species has its own unique adaptations. The marine iguana Amblyrhynchus cristatus of the Galápagos Islands is a skillful swimmer, and its black coloration helps it to warm its body after swimming in the cold ocean. In contrast, the green iguana is at home high in the trees of the tropical rain forest, while other species of iguanas have adaptations that allow them to live successfully in the dry, hot desert.
The dinner bell
Most iguanas are herbivores, eating fruits, flower buds, and young leaves. Some species also eat the occasional juicy mealworm or wax worm! At the San Diego Zoo, our iguanas are fed a fruit salad that includes dark leafy greens and a variety of fruits, while some species are also fed insects like crickets, mealworms, and wax worms. But because wax worms are high in fat, they are considered the “dessert” part of the menu at the Zoo! Speaking of food, iguanas themselves are eaten by a variety of carnivores, including humans. Green iguanas are bred and raised on farms in Central and South America to be eaten by people.
The females of most iguanas dig a burrow in a sunny area, lay their eggs inside, cover them, then leave the eggs alone. The temperature in the burrow stays a fairly constant 77 to 89 degrees Fahrenheit (25 to 32 degrees Celsius). The warm temperature incubates the eggs. All eggs in a nest usually hatch at the same time, and the young dig out of the burrow without help from the parents. On its own, an iguana hatchling faces many dangers. Habitat loss, the introduction of exotic animals that prey on iguanas, capture for the pet trade, and poaching are some of the threats to wild iguana populations. Some species that were once plentiful in the wild are now beginning to disappear. There are several measures that can help iguanas survive, such as captive propagation in zoos, hunting and collecting restrictions, and education programs for people living in or near iguana habitats.
The San Diego Zoo is home to many species of iguanas. As we care for them, we learn important things about them such as ideal conditions for reproducing or special dietary needs. The information we learn can help us to strengthen the chances of survival of the iguana population in the wild. Some things are best learned by studying animals in their natural habitats, so our scientists also observe animals in the wild.
One of the Zoo's most successful iguana conservation programs involves the endangered Jamaican iguana Cyclura collei and Anegada Island iguana Cyclura pinguis, both native to only a few islands in the Caribbean Sea. Cats introduced to the islands by humans have been eating both iguana eggs and the young hatchlings, causing the iguanas' numbers to shrink. The San Diego Zoo is helping these iguanas with a program called "headstarting." Iguana eggs are incubated in safe areas and the hatchlings are taken care of in large pens until they are big enough to protect themselves from the cats, thus giving them a "head start" in the wild.
You can help, too!
Visiting the San Diego Zoo and the San Diego Zoo Safari Park helps the giant rock iguanas of the West Indies, which are the most endangered group of lizards in the world. The rock iguana breeding program at the Zoo has been so successful that a new facility was built to accommodate the growing population of iguanas. Without this expanded facility, the fate of these beautiful iguanas would be less certain. The program not only includes supporting the animals in our facilities, but also includes a field program to establish new populations and to move current populations to small islands with no people so the iguanas have room to grow.