7 Questions About Lizards, Snakes, and Other Reptiles Answered

The lizard is a reptile, a cold-blooded animal that is unable to internally control its own body temperature. In order to warm up or cool down, lizards and other reptiles—such as snakes, turtles, and crocodiles—move to different areas of their environment. Other behavioral traits help to keep their body temperatures constant. For instance, if a lizard is starting to feel the intensity of the tropical sun, it might head into the shade or take a dip in water. The same lizard might also bask in the sun to warm up. Frilled lizards and collared lizards run on their hind legs in the heat of the day, making an artificial breeze to help cool themselves off. And another reptile, the crocodile, holds its jaws open to cool down on hot days. The blood vessels in its mouth are close to the skin surface, and help transfer heat. Lying quietly is another technique the crocodile uses to warm its body and help digest its food. Because they are cold-blooded, reptiles can survive on much less food, compared to warm-blooded small mammals and birds, which burn much of their food to keep warm.

Lizards and snakes smell by licking the air with their tongues. The tongue picks up scents in the form of airborne molecules that the animal then draws back into its mouth. The forked tips of the tongue are inserted into two openings of a special organ, called Jacobson’s organ, which identifies the molecules and passes it on to the brain. Because of this unique organ, lizards and snakes have a keen sense of smell, which they use to track prey and find potential mates.

Generally, snakes show little or no parental care. But a male and female king cobra—the world’s largest venomous snake—often cooperate to find a safe nesting spot for their young. In April, the female builds a nest of dead leaves by scooping them up with her large body. She then lays about 20 to 50 eggs, with an incubation period ranging from 60 to 80 days. The female lies on her nest until just before the eggs hatch, at which point instinct causes her to leave the young (so she does not eat them). The male king cobra guards the nesting area until the young hatch.

Snakes’ bodies are covered with plates and scales, which help them move over hot surfaces including tree bark, rocks, and desert sand. Rough belly scales help a snake keep its grip on rough branches and push off of surfaces when it needs to move. The scales are also waterproof, helping keep water away from the snake’s body. The scales are made up of many layers of cells. The outer cells are dead and protect the living ones underneath them. Several times each year a snake sheds a layer of its dead skin, allowing a new layer to emerge. Before the skin peels, the snake is sluggish, its colors become dull, and its eyes turn cloudy. When a snake is ready to shed its old skin it rubs up against a rough surface, like a rock, to rip its skin. Then it glides out. Snakes shed their skin so they can grow. Shedding skin also removes parasites.

Crocodilians—scaly, carnivorous reptiles that include crocodiles, alligators, caimans, and gharials—are descendants of the archosaurs that lived on Earth more than 200 million years ago. Today’s modern crocodiles are semi-aquatic predators that have remained relatively unchanged since the Triassic period. Besides birds, they are the dinosaurs’ closest living relatives.

There are a number of differences between alligators and crocodiles. Alligators are slightly larger and more bulky than crocodiles. A wild alligator can reach up to 13 feet (3.9 meters) in length, and weigh up to 600 pounds (272 kilograms). Besides the two animals’ size difference, the easiest way to tell them apart is by their snout. A crocodile has a very long, narrow, V-shaped snout, while an alligator has a wider, U-shaped snout. The alligator’s wide snout delivers more crushing power to eat prey—particularly turtles, which make up a large part of the animal’s diet. The crocodile’s upper and lower jaws are nearly the same width, so its teeth are exposed all along the jawline in an interlocking pattern, even when its mouth is closed. An alligator, on the other hand, has a wider upper jaw, so that when its mouth is closed the teeth in the lower jaw fit into sockets of the upper jaw, hidden from view. South Florida is the only known place in the world where crocodiles and alligators live together in the same area.

Lizards and salamanders may look alike, but they are very different from one another. Lizards are reptiles, and salamanders are amphibians. Both are cold-blooded animals that use the environment to help regulate their body temperature. And both animals are vertebrates, which means they have a backbone. An amphibian needs moist conditions in which to live, has smooth and moist skin without scales, and stumpy toes. Salamanders can be found under leaves in a forest or under rocks in a stream. Lizards have dry and scaly skin, have longer toes that can be used for climbing, and live in a dry, hot environment. They can go long periods of time without water. Salamanders lay eggs without shells, and they must lay them in a moist environment. Many salamander eggs need to be laid completely underwater, because when the larvae hatch they soon develop gills and are dependent on water. These aquatic salamanders go through metamorphosis—from tadpole to adult—just as frogs do. Lizard eggs have shells and their nests are typically in the sand. Upon hatching, young lizards do not change or morph.