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Grand Cayman iguana

Scientific name: Cyclura nubila lewisi


CLASS: Reptilia
ORDER: Squamata
FAMILY: Iguanidae

STATISTICS: Weight: 25+ lbs; Length: 5 ft

Grand Cayman blue iguanas are large lizards with red eyes and a row of spines that run from the back of the head to the tip of the tail. The blue coloration is most noticeable in the males of the species, which are slightly larger than the females. This blue color is most pronounced during the breeding season. Unlike green iguanas, blue iguanas have no spines on the dewlap, and no obvious bands on their tails.

Found only on Grand Cayman Island

Rocky areas & brush land areas

Iguanas are ectotherms, meaning they are not able to produce their own body heat like humans do. Like other reptiles, they must rely on their surroundings to help them regulate their body temperatures. The Grand Cayman blue iguana is able to change colors to absorb more or less heat. Early in the day the adult iguana is dark gray and absorbs heat very efficiently. As the animal warms, it changes to a powder blue color, which is paler and does not absorb heat well.

The female is solitary and defends her own small territory, which includes places to bask and feed, and an area of soil deep enough to nest. Males tend to roam around and lead a quiet life during the non-breeding season. In early March, males begin to reassert their dominance and expand their ranges to include as many female territories as possible. Encounters between males will usually result in a high-speed chase, with the larger ones winning, but if they are close in size they will fight viciously, losing toes, tail tips, spines, and chunks of skin.

In late April, the females will become receptive. This is the only time the males’ presence is tolerated. Mating usually occurs during the first two weeks of May. About six weeks after mating, the female will dig a tunnel deep enough so the nest will be the proper temperature and humidity. Then she will lay one to twenty eggs, with mature iguanas laying more eggs than younger iguanas. After laying her eggs the female will disguise the opening to the nest with leaf debris and other materials near the nest. She will guard her nest for a few weeks to make sure her eggs are safe, but will eventually leave the nest site in search of food.

The baby iguanas will hatch after about ten weeks. The eight-inch hatchlings will wait until all their brothers or sisters have hatched, and then together they will dig their way out of the nest. After they reach the surface, they scatter and begin to fend for themselves. Iguanas grow continuously, although the most rapid growth is early in life. Iguanas stretching up to five feet from nose to tail are not uncommon.


Prey to birds and snakes, feral dogs and cats, and humans
Predator to small vertebrates

Fruits, flowers, and leaves


It is listed as Critically Endangered by the IUCN. Current populations are estimated at 100-200 individuals remaining in the wild.


  • When threatened, iguanas will turn their bodies sideways and stand tall, showing the offender the biggest view of themselves. They will fight quite aggressively using their tails as whips and can deliver a painful bite with their powerful jaws. The Grand Cayman blue iguana is much stronger and more aggressive than the green iguana.


  1. Badger, David. Lizards. Raincoast Press, Vancouver, B.C. 2002
  2. Pianka, Eric R., Vitt, Laurie J., Lizards: Windows to the Evolution of Diversity. University of California Press, Berkeley and Los Angeles, California, 2003.
  3. Burton, F.J. 2004. Cyclura lewisi. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. . Downloaded on 17 July 2008.

Published: December 2008


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