View distribution map using BerkeleyMapper.

	Conservation Status (definitions)
IUCN (Red List) Status	Near Threatened (NT) See threat category on Global Amphibian Assessment web site.
CITES	Appendix I
Other International Status	None
National Status	Fully protected by law since 1952; classified as rare (Kato and Ota 1993). NT (Near Threatened) according to the Red Data Book, 2nd ed. (Japan Agency of Environment 2000; Ota 2000)
Regional Status	None

Description
Heavily built salamander. Head broad and flat. Body strongly depressed; terminal two-thirds of tail strongly compressed; nostrils small, near tip of the snout, their distance from each other less than one-half the distance between the eyes, which are without eyelids and very small. Vomerine teeth in an arched series starting between the choanae, parallel to the maxillary and premaxillary series. Thin lower labial fold starting midway between nostril and eye to angle of mouth. Legs short and flattened. Tail short, slightly more than one-third the length of head and body, with a high dorsal fin beginning at insertion of hind legs, and a lower ventral fin. Skin rough, with wrinkles, folds and tubercles. No external sexual dimorphism. During the breeding season, cloacal lips are swollen in the male and flat in the female. Color is reddish-brown, paler below; irregularly blotched and marbled with dusky spots. Total length about 100 cm. Maximum length 144 cm (Thorn 1969). Wide range of total length of adult males (from 30 to 102 cm in wild animals), a result of continuous growth after sexual maturity (Kawamichi and Ueda 1998). A male of 78 cm may weigh 3.3 kilograms. Closely related and very similar to A. davidianus. Genetic variation is low (Matsui and Hayashi 1992; Matsui et al. 2008).

The genus Andrias includes two extant species, the Chinese A. davidianus and the Japanese A. japonicus. These species are the largest living salamanders, with adults reaching a total length of more than 100 cm. Vomerine teeth located on anterior margin of vomer, parallel with maxillary tooth row; teeth form a long arc. Nasals in contact with maxilla; frontal does not enter external naris. Pteroid broad, almost in contact with base of maxilla. Hyoid arches cartilaginous. Two pairs of branchial arches. Body large, no spiracle on head; distance between nostrils less than half the distance between the eyes. Tongue large. Tubercles on highly vascular skin. Permanently aquatic.

The Japanese Giant Salamander is very similar to the Chinese Giant Salamander and differs from the latter by the arrangement of tubercles on the head and throat. These tubercles are larger and more numerous than in A. davidianus; they are mostly single and irregularly scattered. The snout is more rounded and the tail a little shorter in the Japanese species.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan

View distribution map using BerkeleyMapper.

According to Japan Agency of Environment (2000) and the IUCN (Stuart et al. 2008), the species is considered to be Near Threatened (see also Ota 2000).

The salamander occurs in mountain streams with clear cool water flowing through granite and schist regions. These streams have usually rocky or gravel bottoms, a width of some 20 m, and at places shallow, quietly running water. The animals keep themselves concealed in rocky caverns or in burrows on the water's edge (Tago 1927). Vertical distribution 300 to 1000 m asl.

Life History, Abundance, Activity, and Special Behaviors
Spawning occurs in late August, early September. Eggs are deposited in strings containing 400-600 eggs. Diameter of egg 5 mm; diameter of external gelatinous capsule 8 to 15 mm. At water temperatures between 13 degrees and 20 degrees C, embryonic development takes approximately two months (Thorn 1969). Larvae hatch at a total length of 30 mm and start feeding after absorption of yolk. One-year-old larvae measure about 100 mm, three-year-olds reach about 200 mm. At this size larvae start losing their gills. Males reach sexual maturity at 30 cm, females at 40 cm. The species is presumed to take at least five years to reach maturity (Matsui and Hayashi 1992) and is extremely long lived. A specimen in the Amsterdam Zoo lived for 52 years (Tago 1927).

The salamanders are entirely aquatic and nocturnal. They feed on fresh-water crabs, fish, and small amphibians (Tago 1927). Males and females have overlapping home ranges and are more or less sedentary outside the spawning period. During the breeding season, in August-September, both sexes congregate at underwater nest sites, consisting of 100 to 150 cm long burrows into or near the river bank. Nests have a single entrance opening underwater. Favourable nest sites may be used during successive years. Both males and females may occupy more than one nest at the time, with large and heavy males ("den-masters") attempting to monopolise occupancy of the nest sites. Nests are guarded from inside by males, attacking other males who try to enter. Males may also patrol around the nest area, chasing and attacking other males. Females enter the nests more than once and lay their eggs in the cavity, where they are fertilised by the male. At this stage several other males may intrude and try to fertilise the eggs. After spawning, den-masters remain at the nests for more than one month and aggressively guard the eggs until hatching occurs or until late October. Dominance rank of den-masters among males attempting to breed appears to be strong. Dead and heavily injured males have often been found during September (Kawamichi and Ueda 1998).

Trends and Threats
The range of this species is severely fragmented (Ohno 1981). A continuing decline is observed in extent and quality of habitat and in the number of locations where the animal was found (Stuart et al. 2008). Because habitat destruction has increased in recent years, this species is more severely subject to local extinctions than it was in the past, and a more effective protection of its habitat is of immediate necessity (Matsui and Hayashi 1992; Matsui et al. 2008).

Although the prevalence of chytrid infection appears to be high in wild individuals (47 of 126 animals sampled, or 37.3%, were infected with Batrachochytrium dendrobatidis, or Bd), neither infected wild nor infected captive A. japonicus have been reported to show any signs of disease (Goka et al. 2009). Examination of formalin-fixed A. japonicus museum specimens has revealed the presence of Bd infection in specimens collected as early as 1902 (Goka et al. 2009). In addition, Bd haplotypes found on wild A. japonicus are genetically distinct from other strains, including those found on introduced bullfrogs, and Bd genetic variation is higher in Japanese endemic strains of Bd than for strains found in the U.S.A., Ecuador, or Italy (Goka et al. 2009). Taken together, the evidence suggests that Bd is endemic to Japan (as well as having been introduced on non-native species such as bullfrogs) and that host-parasite co-evolution has occurred in the case of A. japonicus and Bd (Goka et al. 2009).

Relation to Humans
This animal used to be hunted for food and medical purposes. The Japanese Giant Salamander was first bred in captivity in the Amsterdam Zoo (Kerbert 1905); in recent years this salamander has been bred successfully in captivity in Japan (Kuwabara et al. 1989). Attempts have been made to rebuild spawning places along the Ichi River (Tochimoto 1995).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat fragmentation

Comments
There is a vast literature on this species, much of it in Japanese. See Stejneger (1907), Sato (1943), Thorn (1969), and for recent ecological studies by T. Tochimoto and J. Kobara in Japanese, see references in Kawamichi and Ueda (1998).

References
 

Goka, K., Yokoyama, J., Une, Y., Kuroki, T., Suzuki, K., Nakahara, M., Kobayashi, A., Inaba, S., Mizutani, T., and Hyatt, A. D. (2009). ''Amphibian chytridiomycosis in Japan: distribution, haplotypes, and possible route of entry into Japan.'' Molecular Ecology, 18, 4757 - 4774.  

Japan Agency of Environment (2000). Threatened Wildlife of Japan - Red Data Book. 2nd ed. Reptilia/Amphibia. (in Japanese with English summary). Japan Wildlife Research Center, Tokyo, Japan.  

Kato, T. and Ota, H. (1993). Endangered Wildlife of Japan. Hoikusha, Osaka, Japan.  

Kawamichi, T., and Ueda, H. (1998). ''Spawning at nests of extra-large males in the Giant Salamander Andrias japonicus.'' Journal of Herpetology, 32, 133-136.  

Kerbert, C. (1905). ''Über die Eier und Larven von Megalobatrachus maximus Schl.'' C. R. 6^e Congr. Intern. Zool., Berne, 1904, 289-294.  

Kobara, J. (1985). The Giant Salamander (in Japanese). Doubutsu-sha, Tokyo, Japan.  

Kuwabara, K., Suzuki, N., Wakabayashi, F., Ashikaga, H., Inoue, T. and Kobara, J. (1989). ''Breeding the Japanese Giant Salamander at Asa Zoological Park.'' International Zoo Yearbook, London, 28, 22-31.  

Matsui, M., Tominaga, A., Liu, W.-Z., and Tanaka-Ueno, T. (2008). ''Reduced genetic variation in the Japanese giant salamander, Andrias japonicus (Amphibia: Caudata) .'' Molecular Phylogeny and Evolution, 49, 318-326.  

Matsui, M., and Hayashi, T. (1992). ''Genetic uniformity in the Japanese Giant Salamander, Andrias japonicus.'' Copeia, 1992, 232-235.  

Ohno, M. (1981). "Megalobatrachus japonicus." Final Report of the Reptiles and Amphibians Survey of the Second National Survey on the Natural Environment of Japan. 1978, pt. 2. Nature Conservancy Society of Japan, Tokyo., 55-70.  

Ota, H. (2000). ''Current status of the threatened amphibians and reptiles of Japan.'' Population Ecology, 42, 5-9.  

Sato, I. (1943). A Monograph of the Tailed Batrachians of Japan (In Japanese). Nippon Shuppan-Sha, Osaka, Japan.  

Stejneger, L. (1907). Herpetology of Japan and Adjacent Territory. Government Printing Office, Washington. Reprinted 1996, with an introduction by M. Matsui. Society for the Study of Amphibians and Reptiles in cooperation with the Herpetological Society of Japan  

Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., and Young, B. (eds.) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.  

Tago, K. (1927). "Notes on the habits and life history of Megalobatrachus japonicus." X^e Congrès International de Zoologie, tenu à Budapest 1927. Budapest., 828-838.  

Thorn, R. (1969). Les Salamandres d'Europe, d'Asie, et d'Afrique du Nord. Lechevalier, Paris, France.  

Tochimoto, T. (1995). ''Ecological studies on the Japanese Giant Salamander, Andrias japonicus, in the Ichi River in Hyogo Prefecture. 10. An attempt to rebuild spawning places along the river.'' Journal of Japanese Association of Zoological Gardens and Aquariums, 37, 7-12.

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