The Japanese giant salamander (Andrias japonicus) is a species of fully aquatic giant salamander endemic to Japan. With a length of up to , it is the third-largest salamander in the world, only being surpassed by the very similar and closely related Chinese giant salamander (A. davidianus) and the South China giant salamander (Andrias sligoi). It is known in Japanese as , literally meaning "giant salamander". Other local names include Hanzaki, Hanzake, and Ankou. This salamander was first catalogued by Europeans when the resident physician of Dejima Island in Nagasaki, Philipp Franz von Siebold, captured an individual and shipped it back to Leiden in the Netherlands, in the 1820s. The species was designated as a special natural monument in 1951, and is federally protected. It is one of the only six species of giant salamanders in the world. Description The Japanese giant salamander can grow to a length of and a weight of . The largest wild specimen on record weighed and was long. It is the third-largest amphibian in the world, only smaller than its close relatives, the South China giant salamander and the Chinese giant salamander. The brown and black mottled skin of A. japonicus provides camouflage against the bottoms of streams and rivers. Its body surface is covered with numerous small warts with distinctive warts concentrating on its head. It has very small eyes with no eyelids and poor eye sight. Its mouth extends across the width of its head, and can open to the width of its body. A. japonicus possesses large skin folds on its neck that effectively increase its overall body surface area. This assists in epidermal gas exchanges, which in turn regulates carbon dioxide and oxygen exchange with the water. Capillaries in the surface of the skin facilitate this gas exchange. The skin folds along each side of the body are more pronounced in the hellbender than in the Japanese giant salamander. The Japanese giant salamander can be distinguished from the Chinese giant salamander by the arrangement of tubercles on the head and throat. The tubercles are larger and more numerous compared to the mostly single and irregularly scattered tubercles of the Chinese giant salamander. The snout is also more rounded, and the tail is slightly shorter. Adult males develop enlarged cloacal glands during the breeding season. Compared to an adult female, an adult male typically possesses a larger and wider head in