Japanese giant salamander

The Japanese giant salamander (Andrias japonicus) lives only in Japan, primarily in the western part of Honshu, with smaller groups on Shikoku and in northern Kyushu. It grows up to 5 feet (1.5 meters) long, making it the third-largest salamander worldwide, behind only the Chinese giant salamander and the South China giant salamander—though the latter is not universally recognized as a distinct species. In Japanese, it is called ōsanshōuo (オオサンショウウオ/大山椒魚), meaning "giant salamander," and also goes by local names like hanzaki, hanzake, and ankou.

Status

Europeans first learned of it in the 1820s when Philipp Franz von Siebold, a physician on Dejima Island in Nagasaki, caught one and sent it to Leiden in the Netherlands. In 1951, the Japanese government declared it a special natural monument, giving it legal protection. Current taxonomy recognizes two to three species in the genus Andrias plus the hellbender, totaling three to four giant salamander species worldwide—not six. This salamander can reach 5 feet (150 cm) and 55 pounds (25 kg), with the largest wild specimen on record weighed 26.3 kg and was 136 cm long.

Description

Its brown and black mottled skin helps it blend into stream and river bottoms. The body is covered with small warts, with larger ones concentrated on the head. It has tiny eyes without eyelids and poor vision, and its mouth spans the width of its head, opening as wide as its body.

Large skin folds on the neck increase surface area, aiding gas exchange through the skin—capillaries in the skin handle carbon dioxide and oxygen exchange with the water. The folds along the sides are less pronounced than in the hellbender. To tell it apart from the Chinese giant salamander, look at the head and throat: the tubercles here are larger and more numerous, unlike the Chinese species' mostly single, irregularly scattered ones. Its snout is rounder, and its tail slightly shorter.

Distribution

During breeding season, adult males develop enlarged cloacal glands, and males generally have larger, wider heads relative to their bodies than females, though sex is hard to determine outside this period. The salamander lives in southwestern Japan, west of Gifu Prefecture on Honshu, and in parts of Shikoku and Kyushu. Robust populations exist in Okayama, Hyogo, Shimane, Tottori, Yamaguchi, Mie, Ehime, Gifu, and Ōita Prefectures.