The Japanese giant salamander (Andrias japonicus) is endemic to Japan, where it is known as Ōsanshōuo (オオサンショウウオ/大山椒魚?), literally meaning "giant pepper fish". With a length of up to almost 1.5 m (5 ft), it is the second-largest salamander in the world, only being surpassed by the very similar and closely related Chinese giant
salamander (A. davidianus).
The Japanese giant
salamander, being restricted to streams with clear, cool water, is entirely aquatic and nocturnal. Unlike other salamanders, which lose their gills early in their lifecycles, they only breach their heads above the surface to obtain air without venturing out of the water and onto land. Also due to their large size and lack of gills, they are confined to flowing water where oxygen is abundant. When threatened, these salamanders can excrete a strong-smelling, milky substance with an odor resembling Japanese pepper (hence its common Japanese name, giant pepper fish).
It has very poor eyesight, and possesses special sensory cells covering its skin, running from head to toe, the lateral line system. These sensory cells' hair-like shapes detect minute vibrations in the environment, and are quite similar to the hair cells of the human inner ear. This feature is essential for its hunting because of its poor eyesight. It feeds mainly on insects, frogs and fish. It has a very slow metabolism and lacks natural competitors. It is a long-lived species, with the captive record being an individual that lived in the Natura Artis Magistra, the Netherlands, for 52 years. In the wild, they may live for nearly 80 years.