Iguanas can grow quite large, up to six feet long including their whip-like tail. Younger iguanas are often bright green, though this becomes more muted as they age, and large adults can appear to be gray, brown and orange. Younger iguanas from different areas can be many colors other than green. For example, in Peru, they are blue, while in Costa Rica and Mexico they may be red or orange.
They have a prominent row of spines on their head and down their back, and a large flap of skin under their chin known as a dewlap. The purpose of this flap is to help the cold-blooded iguana control its body temperature.
Their long tails are capable of being used for defense, striking out at any threats like a whip. If grabbed by a predator, the tail can break off and regenerate.