The Japanese giant salamander is a large species of amphibian native to the Japanese islands of Kyushu and Honshu. The salamander is true to its name, growing to an adult length of 5 feet and weighing up to 55 pounds.
Although very large, it displays many neotenic features, or characteristics retained from earlier life stages. For example, it never develops eyelids. It also lacks gill openings, has a single pair of closed gill slits and possesses only rudimentary lungs. Instead, it breathes through its skin. Despite its weight, the animal has such a slow metabolism that it is capable of going without food for weeks.