In the wild, geckos are found throughout the world. Most inhabit deserts in tropical regions. Some are terrestrial--staying on the ground--while others are arboreal and live in trees. Most species are nocturnal. They are popular lizards to keep as pets.
Geckos are small- to medium-sized lizards, ranging from 33 mm to 350 mm, with a tail about half the length of its body. Some species have fixed eyelids while others have movable eyelids. All geckos have skin that is loose fitting and velvety. Many species are brightly colored and some tree-dwelling geckos have stunning pattens of red, green and blue.
Geckos eat insects and plants. They can be aggressive predators, rushing up to an insect, biting into it, then banging it on the ground to kill it. They will eat any insect that is small enough to can get their mouth around. They lap soft plant matter such as flower nectar or rotting fruit in the same way they drink water.
Geckos are the most vocal members of the lizard family. Their cries take two forms: defensive and aggressive. Defensive cries range from a simple chirp to a scream. Sometimes the gecko will, at the same time, take an aggressive posture, arching its back and opening its mouth. Aggressive cries are generally reserved for fights with other males over territory or for attracting a mate. These cries are usually a series of rapid-fire chirps.
These small lizards have unusual defense tactics. Perhaps the most spectacular is the ejaculatory tail glands of the Strophorus gecko. When threatened, they curl their tale over their back and fire a stream of viscous and irritating liquid from one of the glands. Other geckos use flash coloration--certain species have a blue lining in their mouth and, when threatened, will open their mouths wide to reveal it. Some geckos drop their tales as a defense mechanism, often when physically touched, but sometimes just from stress.