Most of their length is due to their powerful tail. The males possess a large dorsal crest. This can grow as high as three inches. When disturbed they will jump to the ground from as high as 20 feet, with a large crash and run to safety. They also seek safety in the water.
Iguanas are great swimmers.
If an iguana is threatened, and there is no escape, it will defend itself with extremely accurate lashes of its muscular tail. The whips are very powerful and can easily discourage a dog. Males often engage in ritual fights. Fights begin with head bobbing then escalate to tail whipping and biting. When the males want to mate, he will inflate his dewlap, the pouch like skin under his chin, to attract his mate.