Reptiles: Lizard

Range: southern Canada to the tip of South America, most of Europe and Asia, and all of Africa and Australia Habitat: all areas of the world except extreme cold and deep oceans

What is a lizard?

Lizards are part of a group of animals known as reptiles. They are most closely related to snakes. In fact, some lizards look like snakes because they have no legs! Many lizards today resemble the ancient reptiles of the dinosaur era. Their ancestors appeared on Earth over 200 million years ago. In general, lizards have a small head, short neck, and long body and tail. And unlike snakes, most lizards have moveable eyelids. There are currently over 4, 675 lizard species, including iguanas (family Iguanaidae), chameleons (family Chamaeleonidae), geckos (family Gekkonidae), Gila monsters (family Helodermatidae), monitors (families Lanthanotidae and Varanidae), and skinks (family Scincidae).

Lizard homes

Most lizards live on the ground, but others can be found making their homes in trees, burrows, or in the water. Tree dwellers have special toes and often a prehensile tail for grasping thin branches. Those that live in burrows tend to have smaller legs, or none at all, to help them move underground more easily. Marine iguanas Amblyrhynchus cristatus spend much of their lives underwater, although they will come to shore to rest on rocks or a sandy beach. Desert-dwelling lizards like the ground gecko Paroedura pictus usually sleep during the day underneath the warm sand, then come out when the sun has gone down.

Lizard senses

Sight— Most lizards have eyelids, just like we do, that clean and protect their eyes when they blink. But some lizards, like geckos, can’t blink! Instead, they have a clear membrane that shields their eyes from dirt or bright sun. Many lizards, such as iguanas, can see in color. Their colorful body parts allow them to communicate with each other, and help them tell who’s male and who’s female.

Smell and Taste— Lizards smell stuff with their tongues! Just like snakes, a lizard will stick out its tongue to catch scent particles in the air, then pull back its tongue and place those particles on the roof of its mouth where there are special sensory cells. The lizard can use these scent “clues” to find food or a mate, or to detect enemies.

Hearing— Lizards don’t have ear flaps like mammals do. Instead, visible ear openings catch sound, and their eardrums are just below the surface of their skin. Even so, lizards can’t hear as well as we do, but they can hear better than snakes!

Pick me!

Male lizards use a variety of methods to attract a female’s attention. They bob their heads vigorously, or display their brightest colors or best features. The green anole lizard Anolis carolinensis inflates a rust-colored throat sack to win over the lady of his choice, sometimes keeping this display for hours. Other males may fight with each other until the weaker one gives up.

Baby lizards come prepared

Most female lizards lay soft, leathery eggs, then call it a day—they don’t stick around to protect the eggs from harm, or keep them warm. Fortunately, the newly-hatched lizards are able to take care of themselves right away, without the mother’s help. Of course, there are exceptions to soft eggs and lack of care in the lizard world! The tokay gecko’s Gekko gecko soft eggs harden in the dry air and stick to the surface on which they were laid. The sandstone gecko’s Gekko petricolus eggs are hard because they are laid in rocky crevices. Some skink mothers will return to the nest to warm their eggs, and some female skinks give birth to live young. The Nile monitor lizard Varanus niloticus lays her eggs in termite mounds. The heat from the termites in the mound helps incubate the eggs. No matter what the circumstances of their birth, baby lizards look like tiny versions of their parents when they hatch.

Out with the old!

Lizards have dry, scaly skin that does not grow with their bodies. So lizards will shed, or molt, their old skin in large flakes to make way for the new skin growth underneath. The scales on lizards vary, depending on their habitat. Skinks have smooth scales so mud won’t cling to them; others have bony plates under their scales for added protection from rough terrain.

Great escapes

Several types of lizards are able to escape from an enemy’s grasp by breaking off part of their tail. The tail has a weak spot just for this purpose, so if the lizard is grabbed by the tail, it easily comes off. The tail can grow back over time, although it won’t look quite the same. Still, it’s better than being someone else’s dinner! Other lizards have different ways to stay safe. Horned lizards Phrynosoma sp. are able to squirt blood from tiny blood vessels in their eyes to scare away or confuse a predator. The armadillo lizard Cordylus cataphractus can roll up into a tight ball to protect its soft belly from attack. The sungazer lizard Cordylus giganteus has impressive spikes that cover its body, including the tail. And the Australian frilled lizard Chlamydosaurus kingii has a “frill” of loose skin around its neck that can stick out when the lizard is frightened. This makes the lizard look much bigger than it really is, and a predator may decide to look for something smaller to eat.

Lizard lunch

Different lizard species eat different types of food. Some are predators, eating mammals, birds, and other reptiles. Others are mainly vegetarian, eating leaves, fruits, and flowers. But most are insect eaters, grabbing crickets, flies, grasshoppers, and more with long, sticky tongues or quick bites. At the San Diego Zoo our lizards are fed a variety of insects, worms, and ground meat as well as fruits and vegetables.