Salamander (Cryptobranchus alleganiensis, family Cryptobranchidae) found in swift-flowing rivers in the eastern and central U.S. It grows to about 25 in. (63 cm) long, has a stout body, flat head, broad tail fin, and wrinkled sides, and is typically brownish gray with black spots. Adults have lungs, but a gill slit persists from the larval stage on each side behind the head. Wrinkled fleshy folds on the body and legs increase surface area for respiration through the skin, the principal mode of oxygen intake. Hellbenders lie under stones during the day, emerging at night to feed on crayfish, small fishes, and worms.