Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Green Iguana Dewlaps

©2000 Melissa Kaplan

Picture in your mind seeing the iguana at a distance, dewlap tucked up or in a relaxed position, the iguana at rest on the branch of the tree in which he is basking.

Now picture the iguana upright on its fully extended legs, body laterally compressed to make it look taller, and the dewlap rigidly extended down and slightly forward. See the subtympanic scale? Doesn't it look like a big eye on a big lizard head? Too big and scary for my lunch! ;)

All of the iguanids (anoles, swifts, basilisks, etc.) have an extendable dewlap or some extra skin under their that can be puffed out a bit in response to a perceived threat from a predator, in territorial display to conspecifics (other members of its own species), and in some cases, when displaying for females. Interestingly (okay, interesting to me) is the fact that only the green iguana has the subtympanic scale. Why did they evolve it? Or lose it, as in the case of the Galápagos marine and land iguanas, who evolved (say DNA testing) 10,000,000 million years ago from green iguanas?