Iguanas Anoles and Relatives: Iguanidae

Iguanids are cold-blooded, which means that their body temperature varies with the outside weather. At night, when it is cool, many species sleep in burrows. In the morning, iguanids emerge from their burrows and rest in the sun to warm up. They are often seen stretched out on a rock. It is necessary for them to raise their body temperature to prepare for the day's activities of feeding, perhaps breeding, and escaping ever-present predators. All iguanids are diurnal (die-UR-nuhl), meaning that they are active during the daytime. If the temperature grows too warm, these lizards find a shady spot so that they do not become overheated.

Iguanids have many predators, among them, snakes, birds, cats, rats, and wild dogs. When a predator approaches, some species remain still and blend into the surroundings. Others are quick runners and dash off almost immediately. They hide under rocks or between thick leaves and bury themselves in sand. A few species use special tactics to avoid their predators. The common chuckwalla fixes itself into a crack between rocks and then puffs up, making itself nearly impossible to remove. Horned lizards puff up too, which makes their spines stand up even higher. Biting predators will avoid the sharp spines. The zebra-tailed lizard keeps changing direction when it runs, as a way to confuse its pursuer. Other lizards squirm under the sand, so they cannot be seen.

Iguanids have lively mating behavior. Body movements include head bobbing, pushups, and open-mouth displays. Some species inflate their chests and throats and extend their dewlaps, or throat flaps, showing bright colors. They might also curl their tails or even show bright body colors.

After courtship, mating takes place. Most iguanids are oviparous (oh-VIH-puh-rus), meaning that they lay eggs. From one to sixty eggs may be laid at one time, and egg laying may take place once or as many as four times a year. The young hatch from the eggs in one to two months. A few iguanids, such as the blue spiny lizard and the short-horned lizard, give birth to live young. Usually, the parents do not care for them. The young must find their own shelter and food immediately after birth. A few species, such as the rhinoceros iguana, will protect their egg groups for a short while. They may guard the nests with threatening body displays or even physical attacks.