Lizards belong to the suborder Sauria of the order Squamata. There are 16 families and more than 3,700 species of lizards. About 30 species are native to the United States, chiefly to the West.

of the Eastern Hemisphere include the frilled lizard and the thorny dragon of Australia and the ftying dragon of southeastern Asia.

Agamid lizards belong to the family Agamidae. The frilled lizard is Chlamydosaurus kingii; flying dragon, Draco volans; thorny dragon, Moloch horridus.

have streamlined bodies. Some have no limbs; others have short limbs. Anguid lizards include the glass snakes of the southern United States, the alligator lizards of the western United States, the slowworm of the Eastern Hemisphere, and the California legless lizard.

Anguid lizards belong to the family Anguidae. Glass snakes belong to the genus Ophisaurus; alligator lizards to the genera Elgaria and Gerrhonotus. The slowworm is Anguis fragilis; the California legless lizard is Anniela pulchra.

Glass lizards are often mistaken for snakes. These lizards have no legs, and they are long and slender in shape. They are called glass lizards because their tails are very brittle and can easily snap off.

Many people call these lizards glass snakes. But glass lizards have ear openings and movable eyelids. Snakes do not.

Glass lizards live in the southeastern and central parts of the United States and in Mexico, Europe, Asia, and Africa. Some of these lizards grow to be about 2 feet (0.6 meter) long, with tails that are twice as long as their bodies. There are 14 species, or types, of glass lizard.

A glass lizard’s tail is very fragile, or easily broken. A predator can snap off the glass lizard’s tail during an attack. But this can actually be a good thing. The tail can wriggle for a short time after breaking off. This may distract the attacker and allow the glass lizard to escape. The lizard does not seem to miss its tail. In time it grows a new, shorter tail.

Several other kinds of lizard, including geckos and skinks, can break off their tail and grow a new one. The same lizard can lose its tail many times and grow a new one after each loss. The new tail may be shorter and fatter, and may have different markings. It begins to grow right after the old tail is snapped off.

Lizards’ tails are used for many other things in addition to defense. They help the lizards balance while walking or running. They store fat, which can be used when food is scarce. And, some lizards also use their tails as an “extra leg” to grasp branches while they climb.

include the Gila monster and its close relative, the Mexican beaded lizard, or horrid heloderm, of Mexico and Central America.

are tree-dwelling lizards that can change color.

Chameleons belong to the family Chamaeleontidae.

are chiefly tree-dwellers that are active at night.

Geckos belong to the family Gekkonidae.

are large lizards, up to six feet (1.8 m) long, that live chiefly in tropical America. Several species occur in the United States, including the desert iguana of western deserts, and the collared lizards, basilisks, swifts, spiny lizards, fence lizards, horned toads, and chuckwallas that live chiefly in the West and Southwest. The anoles of the Southeast also belong to this family.

Iguanas belong to the family Iguanidae. The desert iguana is Dipsosaurus dorsalis. Collared lizards belong to the genus Crotaphytus; basilisks, Basiliscus; swifts and spiny and fence lizards, Sceloporus; horned toads, Phrynosoma; chuckwallas, Sauromalus; anoles, Anolis.

are large Old World lizards. Many live near rivers. Monitors eat fish, birds, and any other animals they can overpower. This group includes the Nile monitor, which grows to be six feet (1.8 m) long, the goanna of Australia, and the dragon of Komodo.

Monitors belong to the family Varanidae. The Nile monitor is Varanus niloticus; goanna, V. varius; dragon of Komodo, V. komodoensis.

are found in western deserts. They have large, protruding eyes with vertical pupils but without movable eyelids.

Night lizards belong to the family Xantusidae.

most common of all lizards, are found in almost all parts of the world.

Skinks belong to the family Scincidae. The stumplailed skink is Trachysaurus rugosus.

are widespread in Europe, Africa, and Asia. They have conical heads and well-developed limbs. Wall lizards, such as the viviparous lizard, are usually seen among rocks or on walls. Sand lizards, such as the European sand lizard, are usually seen in sandy, open areas.

Wall and sand lizards belong to the family Lacertidae. The viviparous lizard is Lacerta vivipara; the European sand lizard, L. agilis.

are native to the Americas. Their tails are often twice as long as their bodies. They are noted for speed. In the United States they do not exceed 12 inches (30 cm) in length, but they grow to 48 inches (120 cm) in the tropics. The tegu usually grows to be 36 inches (90 cm) long.

Whiptails and racerunners belong to the family Teiidae. The tegu is Tupinambis teguixin.

Most animals, including lizards, need both a female and a male to mate in order to reproduce, or have offspring. But the females of about 30 species of lizard can reproduce when a male is not present.

The offspring of these lizards are all female. A single female lizard is able to lay eggs or give birth to young lizards that are clones of (genetically identical to) their mother. The females of 10 species of whiptail lizard from the southwestern United States and Mexico are among those who reproduce without males.

There are pluses and minuses to being able to reproduce without a male. One good thing is that the lizards do not need to spend time finding or fighting over mates. Because of this, a group can increase in size quickly. But one bad thing is that the offspring are genetically identical to their mother (and to each other). Genetic diversity is good for a species. It gives a species a better chance of adapting to different or changing environments.

are burrowing lizards shaped like worms. They have no ear holes, and their eyes are partly covered with skin. The Florida worm lizard, pink to red, grows to a length of 14 inches (35 cm). Worm lizards are also found in South America, Spain, and Africa.

Worm lizards belong to the family Amphisbaenidae. The Florida worm lizard is Rhineurafloridana.