Most water-dwelling species have webbed toes on their hind feet. The smaller front legs, or arms, prop a frog up when it sits. The front legs also help break the animal's fall when it jumps. Frogs that live in trees have tiny, sticky pads on the ends of their fingers and toes. The pads help the animal cling to the tree trunk as it climbs.
Most frogs have thin, moist skin.
Many species have poison glands in their skin. The poison oozes onto the skin and helps protect the frog. If an enemy grabs a frog, the poison irritates the enemy's mouth and causes the animal to release the frog. Frogs have no hair, though the males of one African species, the so-called hairy frog, look hairy during the mating season. At that time, tiny, blood-rich growths called papillae, which resemble hair, grow from the sides of the frog's body.