The hellbender (Cryptobranchus alleganiensis), also known as the hellbender salamander, is a species of aquatic giant salamander endemic to the eastern and central United States. It is the largest salamander in North America. A member of the family Cryptobranchidae, the hellbender is the only extant member of the genus Cryptobranchus. Other closely related salamanders in the same family are in the genus Andrias, which contains the Japanese and Chinese giant salamanders. The hellbender, which is much larger than all other salamanders in its geographic range, employs an unusual means of respiration (which involves cutaneous gas exchange through capillaries found in its dorsoventral skin folds), and fills a particular niche—both as a predator and prey—in its ecosystem, which either it or its ancestors have occupied for around 65 million years. The species is listed as Near Threatened on the IUCN Red List of Threatened Species. C. alleganiensis has a flat body and head, with beady dorsal eyes and slimy skin. Like most salamanders, it has short legs with four toes on the front legs and five on its back limbs, and its tail is keeled for propulsion. Their tail is shaped like a rudder, but it is rarely used for swimming; these salamanders use pads on their toes instead to grip rocks and walk up and down streams instead of swimming. The hellbender has working lungs, but gill slits are often retained, although only immature specimens have true gills; the hellbender absorbs oxygen from the water through capillaries of its side frills. Only occasionally leaving the water, the hellbender makes little use of these lungs and the juveniles lose their external lungs after around 18 months Hellbenders use their lungs for buoyancy more than breathing. It is blotchy brown or red-brown in color, with a paler underbelly. (Source: Wikipedia.org, CC BY-SA)