Snakes and Lizards: Squamata

Because they are ectothermic (ek-toe-THERM-ik), which means that their body temperature changes based on the outside temperature, many squamates sunbathe, or bask, to warm up. Others, however, stay out of sight during the day. Some of the fossorial species rarely come out of the ground at all. These species will sometimes increase their body temperatures by moving to a warmer underground spot. For hunting, many of the squamates actively walk or slither about looking for prey. Others, however, hunt by ambush, which means that they sit still, wait for a prey animal to come along, then spring out to grab and eat it. Some snakes, including the pit vipers and the boas, have a special method of hunting. They can sense heat through small holes, called pit organs, on the face. Using these pit organs, they are able actually to see the heat given off by an animal in 3-D. These pit organs come in especially handy when hunting for food at night or in places where the snake has a limited view.

Compared to mammals and birds, squamates must have meals much less frequently. Because they are ectothermic and do not have to use their energy to keep up a constant body temperature, as the mammals and birds do, they can get by on much less food. Some of the large snakes can survive many months —even a full year—on one big meal.

Depending on the species, a squamate female may lay eggs or give birth to live young. Many species lay their eggs in nests, which are little more than holes dug in moist ground. A few, like the wormlizards, lay their eggs inside ant or termite nests. Most squamate mothers provide no care for their young and leave almost immediately after they lay their eggs or give birth. Some lizards and snakes are exceptions. Many female skinks, for example, stay with the eggs until they hatch.

While most species reproduce only after the male and female mate, some species are parthenogenic (parth-enn-oh-GEN-ik), which means that a female can produce young by herself. In many of these species, such as the lizard known as the desert grassland whiptail, only females exist. The female's young are all identical copies of herself. Besides this species in the whiptail family of lizards, seven other families of lizards and snakes have some all-female species.