Lizards are reptiles, which means they are cold-blooded, lay eggs, and covered by scales instead of feathers or fur. Different types of lizards might live in trees, underground, on the banks of rivers, or in the desert. Some varieties eat insects, others fruit, and still others prey on small mammals. They come in all colors and sizes, equipped with innovative methods of defense, reproduction, and predation.

Depending on who you ask, lizards are divided into anywhere from 6 to 16 families. Each family shares general characteristics, like where they can survive, how they look, and what they eat. In each family are many different species. Some lizards look like dinosaurs, while others are small enough to perch on the tip of your finger.

Everyone recognizes chameleons' human-like hands as they grasp branches. They are equipped with an opposable thumb and fingers to let them crawl through trees in Asia, the Mediterranean, and sub-Saharan Africa. Their prehensile tails curl and wrap around stems to help with climbing, similar to a monkey's tail. Like frogs, their sticky tongues dart out to catch flying insects. Each eye, enclosed in a convex socket, can move independently, which helps it watch for flies. Chameleons indeed change the shade of their scales based on emotions related to fear or reproductive urges.

Skinks are a lesser-known type of lizard. They are often mistaken for a kind of snake because they have tiny, smooth scales on a long, cylindrical body. Also like snakes, they exhibit intricate, beautiful, colorful patterns. Skinks enjoy semi-arid environments like meadows or sandy hills where they dig burrows for protection. Another useful trait is their tail's ability to break off when grabbed by a predator, allowing them to quickly slink away.

Iguanas are a popular type of lizard because they make friendly pets. In the wild, some species of iguana can grow quite large while they roam through arid and temperate climates. They're entirely vegetarian, snacking on leaves and sweet fruits. Their main defense is their sharply spiked tail that they can whip around when feeling threatened. Green varieties stay up in trees while brown iguanas stick to the ground, digging burrow.

A few specific species of lizards are worth mentioning. Gila monsters live predominantly in the Southwestern United States where they burrow under the hot desert ground. The unique banded design of their scales is often colored red and black. Bright colors warn other animals that they are venomous. Indeed, although they scavenge bird and reptile eggs, they deliver a poisonous bite as a defensive measure. If you're lucky, they'll hiss first as a warning.

Geckos are diminutive, tropical lizards with bright green bodies and often orange or yellow feet. Their fascinating toes, like suction cups, allow them to shimmy up vertical surfaces in their search for insects. Sometimes people see them climbing glass windows with ease. Their oversized eyes let in more light for nocturnal hunting.