How does a green iguana protect itself when a predator attack?

The first line of defense for an iguana is to be up off the ground and in the trees as they're arboreal. The second line of defense is camouflage; best to try and avoid trouble in the first place.

If those don't work, iguanas have very very powerful tails that they use to literally whip their adversaries. I've had this done to me by a juvenile and it sure leaves a mark! Should their tails get grabbed, they can drop, or "autotomize" their tails, leaving the predator distracted while they scurry off to safety.