Gecko, any of more than 400 species of small harmless lizards found in warm climates. The gecko's name is derived from the sound of the cry of one species. Geckos are most numerous in southeastern Asia, Africa, and Australia. The largest gecko is the tokay of Malaysia, 10 to 14 inches (25 to 36 cm) long. Two geckos, both about 4 inches (10 cm) long, are native to the southwestern United States—the banded gecko (brownish with yellow bands) and the leaffingered gecko.

The banded geckoThe banded gecko is native to the southwestern United States.

The gecko's tapering head and short, flat body are covered with tiny scales that give the skin a soft appearance. Many species have brittle tails that break off easily. The leaf-fingered gecko is among the many species that have clinging pads at the tips of their toes, enabling them to run on walls and ceilings. Geckos move about only at night, feeding mainly on insects.

How Do Geckos Walk on the Ceiling?

Scientists used to think that geckos had disks on their toes that worked like suction cups. But now we know that it is the hairs on the underside of these lizards’ toes that help the animals climb and cling.

The toes of most geckos end with pads that have thousands of tiny, stiff hairs. These hairs stick to most surfaces, making the animals good climbers. Some geckos can walk upside down on the underside of a branch, ceiling, or other flat surface.

Since geckos’ feet stick to whatever surface they are on, why don’t these hairs prevent the lizards from walking and jumping? Because, luckily, geckos have a way to keep from getting stuck in place. Each of a gecko’s toes can be curled away from the surface it is on. This loosens the clinging hairs and allows the animal to move.

The tokay is Gekko gecko; the banded gecko, Coleonyx variegatus; the leaf-fingered gecko, Phylo-dactylus tuberculosus. Geckos belong to the gecko families Gekkonidae, Eublepharidae, and Diplodactylidae.