Most lizards eat insects, spiders, and scorpions. Iguanas and some others live chiefly on plant food. Monitors and a number of other lizards eat amphibians, reptiles, birds, and mammals. The dragon of Komodo catches and eats animals as large as deer.

Lizards are preyed upon by snakes, birds, and various other meat-eating animals. Some, such as iguanas, are eaten by human beings. Some are killed for their skins, which are made into shoes, handbags, and other items. Some lizards, such as the tegu and the chameleon, are kept as pets.

Most lizards reproduce sexually—that is, their eggs must be fertilized to produce offspring. Some lizards, such as whiptails, sometimes reproduce asexually—their eggs produce offspring without being fertilized. Lizards of most species are hatched from eggs laid beneath a log or buried in soil. The young of some species hatch from eggs with in the mother's body or are born fully developed. Lizards generally must fend for themselves from birth.

Most lizard eggs are not waterproof. The shells have to be able to let moisture in so that the growing lizards can get the moisture they need to develop and hatch properly. The female lizards often lay their eggs in damp soil, fallen leaves, and rotting wood, all of which have the necessary moisture. Even sand can be a safe place for a nest, if the lizard digs down far enough to reach some water.

After laying their eggs, most females leave them alone to develop and hatch. The eggs are easy targets for other animals—they make the perfect snack. In most species of lizard, the eggs are white and are easy for animals to spot in a nest that is not well hidden. In some Central and South American countries, people eat lizard eggs.

Most female lizards lay eggs. But the females of some species give birth to live young. Among lizards that do lay eggs, most eggs require several weeks or even a few months to hatch. The eggs of a panther chameleon may need 240 or more days to develop before hatching.

Lizards are unable to maintain a constant body temperature. For this reason they must shelter in cool places in hot weather, and hibernate in burrows or other protected places in winter.

Lizards can run at a rate of up to 15 miles an hour (24 km/h), and many kinds depend on speed to escape enemies. Many lizards are protectively colored. Horns and spines protect the horned toad and many other lizards. Almost all lizards can, and will, bite, but only the Gila monster and the Mexican beaded lizard are venomous. To frighten or confuse enemies, the horned toad squirts blood from its eyes, while the frilled lizard spreads the large disk of skin about its neck in order to appear larger to its enemies.

Head-bobbing is a way that lizards communicate. Male anoles nod their heads up and down to signal to other anoles that they are males and to chase off other males at mating time.

Bobbing sometimes means a male is ready to fight another animal. It also can mean that the animal is defending its territory.

Some lizards do “push-ups” for the same reason. They push up with their front legs, which may make them look larger to an opponent.

Each species of lizard has its own pattern of head-bobbing and push-ups. This is one way in which lizards can tell which individuals belong to their own species.

Other ways in which lizards communicate include waving their tails, opening their jaws wide, changing their colors, sticking out their dewlaps, or showing off their brightly colored undersides.

Yes, lizards defend themselves in many ways.

The most common self-defense for a lizard is running away. But some lizards do the opposite: they freeze when they see an enemy, counting on their camouflage colors or bright patterns to help hide them. A few species of lizards even “play dead.” These lizards hope they will not be interesting to a predator if that predator thinks they are already dead.

Just as the glass lizard uses its tail to distract an attacker, other lizards also bluff, or play tricks. Some try to look more fierce than they are by lashing their tails, hissing, or puffing out their bodies to look larger.Some lizards, including monitors, use their jaws for biting. They clamp their jaws and sink their teeth into an attacker’s body and then hang on. Even a lizard that is not poisonous can do a lot of damage by biting its enemy.

Some species of lizard are endangered, and others are threatened. In many areas, the lizards’ habitats have been destroyed. Forests have been cut down, roads have been built, and wetlands have been drained or dammed.

In the past, some lizards were killed for their skins. These skins were used to make wallets, handbags, and other products. But many countries now forbid killing lizards for this purpose. In some countries, people still kill lizards to eat, or eat the lizards’ eggs.

Marine iguanas are threatened by oil spills near their home in the Galapagos Islands. There was a bad oil spill near the Galapagos Islands in 2001. The next year, scientists said that about 15,000 marine iguanas had died on a nearby island.

More than two dozen species of lizards are officially called endangered, and many more are considered vulnerable. Among the endangered species are the Fiji crested iguana, the Coachella Valley fringe-toed lizard, and a legless species of skink.