Lizards are members of the reptile family. Other members are snakes, turtles, crocodiles and alligators. Lizards have several things in common with other reptiles. All reptiles are cold-blooded. They cannot control their own body temperature. It is controlled by their surroundings. Lizards must work to maintain their temperature. Another characteristic which lizards have in common with all reptiles is that their skin is made of scales.
Lizards shed their skin frequently because the skin doesn't grow with them. They have lungs and breathe like humans. They breathe through nostrils above their mouths. They have a special organ on the roof of their mouth. It is a Jacobson's organ. Lizards smell with this. They pick up the smells with their tongues. The smells travel to the Jacobson's organ. Lizards can sense prey this way. Their eyes and ears are located on either side of their heads.
Lizards have a simple body shape. They have a head, a pair of legs, a long body, another pair of legs and a tail. Their tails can help them balance, swim, or grab tree branches. Some lizards use their tails as a weapon. They can also wiggle away from a predator which grabs their tail. Certain muscles will cause it to fall off, but the tail still moves. The predator watches the tail, and the lizards can escape. Then lizards can grow a new tail. Lizards range in size from one and one-half inches long to seven and one-half feet. The Komodo dragon is the biggest lizard. The Komodo dragons live in Indonesia. The smallest lizards live in the British Virgin Islands.
Lizards can be found on every continent except Antarctica. Many live in tropical rain forests. Food is plentiful for them there. The hot damp climate allows them to maintain their body temperatures. They can be found also in deserts and other hot, dry areas. Many of the desert lizards are nocturnal. They come out in the cooler evening. Very hot weather is not good for them. Lizards that live in cold climates hibernate through the winter. Their bodies can't tolerate the cold temperatures. Also, food is not as readily available in the winter.
Some lizards are carnivores and some are herbivores. Large carnivores like the Komodo dragon will eat anything they can find. They need a lot of food so will hunt bigger prey, like deer and cattle. Gila monsters are also rather large lizards. They usually look for baby birds and mice. They bite their prey. Poison flows from their mouths into the wound. Gila monsters are the only venomous lizards in the United States. Smaller carnivores eat insects, other lizards and small animals. Herbivores eat leaves, fruit, flowers and other plants. They can more easily obtain food. They don't have to hunt or wait in hiding like the carnivores.
Lizards are prey to birds, snakes, bears, raccoons, and coyotes. They try to avoid the predators by hiding underground or behind rocks during the day. At night they stay in a nice warm burrow under the ground.
In summary, lizards are members of the reptile family. Like reptiles, they are cold-blooded. Their temperature is controlled by their environment. They have to work at keeping their bodies at a comfortable temperature. Also, like reptiles, their skin is composed of scales.