What Is A Green Iguanas Chin-Flap For?

Why do green iguanas like Pip have extra flaps of skin beneath their chins?

The male iguana has a dewlap on the chin. What is a dewlap? It is a special flap used to attract female green iguanas and intimidate predators that would attack them. The dewlaps help the iguanas appear much bigger than they really are.

Females also have a dewlap, though theirs are smaller than males. Females, like males, use the flap to appear bigger, allowing them to dominate other females, scare off predators, and so on. Females will also use it to regulate body temperature.