Explore by Animal

Grand Cayman Blue Iguanas

It’s a battle cry worth heeding. A 2002 report issued by the National Trust for the Cayman Islands said fewer than 30 Grand Cayman blue iguanas (Cyclura lewisi) remained in the wild. Fewer than 120 existed globally when you added those living at zoos, aquariums and conservation centers. Without intervention, the report said, the blue iguana would be functionally extinct by 2007. Let’s put on our boots and start marching.

The blue iguana is found only on Grand Cayman, a tiny, rocky island in the British West Indies. It can grow to
5 feet long and eats a vegetarian menu of leaves, flowers and fruit. During the mating season, hormones turn the males electric blue while the females brighten to powder blue.

Preferring a solitary life, females will ferociously defend fixed territories while males tend to casually roam around or bask. The pace quickens in spring, when males chase or battle one another over females. Once a female is fertilized, she will burrow until she finds the perfect conditions for building a nest, then ram her way back out and disguise the nest with soil and debris. Each juvenile arduously opens its shell over a prolonged period. Once all the hatchlings are out of their shells and have regained their strength, they thrust through the soil in a single line and scatter into the undergrowth.

Predation by cats and dogs and habitat loss are among the blue iguanas’ biggest killers. Shedd Aquarium is one of 10 U.S. institutions trying to breed these vanishing iguanas, supporting the blue iguana recovery program on Grand Cayman, which is now restoring captive- reared young blue iguanas to the wild in protected areas. Long off exhibit, our pair, Marley and Eleanor, moved into a new 1,200-square-foot rocky habitat in Waters of the World in 2005. Not only do visitors have a closer view than in the wild, but learning about them is a powerful means to help prevent their extinction.


Each year Shedd staff members head to the Bahamas with a group of volunteers to study West Indian rock iguana populations. Read a blog about their experience.

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