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. These structures provide males with extra oxygen during a period when they are very active. Some species of frogs change their skin color with changes in the humidity, light, and temperature.
Frogs shed the outer layer of their skin many times a year.
Using their forelegs, they pull the old skin off over their head. They then usually eat the old skin. Frogs have fairly good eyesight, which helps them in capturing food and avoiding enemies. A frog's eyes bulge out, enabling the animal to see in almost all directions. Frogs can close their eyes by pulling the eyeballs deeper into their sockets.