Rhinoceros Iguana

Part of the Lizards and Snakes: Alive! exhibition.

Rhinoceros Iguana
© AMNH / Denis Finnin

Why is this big lizard perched there, powerful and--though he may not look it--alert? Because he's basking, absorbing heat from the environment.


Rhinoceros Iguanas, like all squamates, must warm themselves from external sources. Clever solar collectors, they shift position as the sun moves to fine-tune internal temperature.


Like all squamates, this Rhinoceros Iguana is covered in scales--small, hard, platelike thickenings of the skin. Scales protect bodies and help reduce water loss. Unlike fish scales, squamate scales are specialized folds of skin.


These big, heavy-bodied iguanas were once the largest animals on the Caribbean islands where they live. Their only enemies were--likely--birds of prey, such as hawks. Today, they are food for humans and their pets.

A green-colored Rhinoceros Iguana on rocky dry soil.
Rhinoceros Iguana
© AMNH / Roderick Mickens


No one knows the function of the horns that give the Rhinoceros Iguana its common name. Bigger in males than females, they may be useful in combat among males and in displays such as head-bobbing.


Male Iguanas display this structure, called a "dewlap," when they are communicating with other males. Like many lizards, they hiss, thrash their tails and bob their heads when threatened or defending territory.

Collecting Heat

To get warm enough to move around and digest their food, lizards lie in the sun or on hot rocks. And because they have scales and don't sweat, they cool down by moving into the shade or underground.

Meet the Family

A few of the 40 or so species in the family Iguanidae are medium-sized lizards, between 15 and 30 centimeters (six inches and one foot) long. But most species are large, and none is larger than the Rhinoceros Iguana. These animals have successfully crossed ocean barriers; several species live on remote islands.

A Brachylophus fasciatus, known as the Fiji crested iguana, on a log.
Fiji crested iguana (Brachylophus fasciatus)
© Patricio Robles Gil / naturepl.com

Fiji Crested Iguana

Brachylophus fasciatus

The ancient ancestors of this iguana species may have arrived at remote Fiji from Central America, more than 7,000 miles (about 11,000 kilometers), on floating clumps of vegetation.




Adult Male Virgin Islands Rock Iguana (Cyclura pinguis) Critically endangered species.
© Jack Goldfarb, Texas Tech University

Fast Facts

Name: Rhinoceros Iguana; Cyclura cornuta
Size: 1 to 1.2 meters (3 to 4 feet)
Range: Haiti and Dominican Republic
Diet: Plants, some insects