Japanese giant salamander - AbsoluteAstronomy.com

The Japanese giant salamander (Andrias japonicus) is endemic to Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, where it is known as , literally meaning "giant pepper fish". With a length of up to almost 1.5 meters (5 ft), it is the second largest salamander

Salamander

Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant...

in the world, only being surpassed by the very similar and closely related Chinese giant salamander

Chinese giant salamander

The Chinese giant salamander is the largest salamander in the world, reaching a length of 180 cm , although it rarely – if ever – reaches that size today...

(A. davidianus).

Behavior

The Japanese giant salamander, being restricted to stream

Stream

A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

s with clear cool water, is entirely aquatic

Aquatic animal

An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

and nocturnal. Unlike other salamanders who lose their gill

Gill

A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s early in their life cycle, 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

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

is abundant. When threatened, these salamanders can excrete a strong-smelling milky substance whose odor resembles that of Japanese pepper (hence its name, giant pepper fish). It has very poor eyesight, and possesses special sensory cells covering its skin, running from head to toe and termed the lateral line

Lateral line

The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...

system. These sensory cells host hair-like shapes that detect minute vibrations in the environment, and are quite similar to the hair cell

Hair cell

Hair cells are the sensory receptors of both the auditory system and the vestibular system in all vertebrates. In mammals, the auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear...

s 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

Metabolism

Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

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

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

, for 52 years. In the wild they may live for nearly 80 years.

History

The Japanese giant salamander was first catalogued by Europeans when the resident physician of Dejima

Dejima

was a small fan-shaped artificial island built in the bay of Nagasaki in 1634. This island, which was formed by digging a canal through a small peninsula, remained as the single place of direct trade and exchange between Japan and the outside world during the Edo period. Dejima was built to...

island in Nagasaki, Philipp Franz von Siebold

Philipp Franz von Siebold

Philipp Franz Balthasar von Siebold was a German physician and traveller. He was the first European to teach Western medicine in Japan...

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 has been protected. It is a survivor from the Upper Jurassic period, some 140 million years ago.

Status

The Japanese giant salamander is threatened by pollution, habitat loss (among other changes, by the silting up of the rivers where it lives), and over-collecting. It is considered near threatened

Near Threatened

Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...

by IUCN, and is included on CITES Appendix I. It can be found on the islands of Kyushu

Kyushu

is the third largest island of Japan and most southwesterly of its four main islands. Its alternate ancient names include , , and . The historical regional name is referred to Kyushu and its surrounding islands....

, Honshu

Honshu

is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...

and Shikoku

Shikoku

is the smallest and least populous of the four main islands of Japan, located south of Honshū and east of the island of Kyūshū. Its ancient names include Iyo-no-futana-shima , Iyo-shima , and Futana-shima...

in Japan. In the past they were fished out of rivers and streams as a source of food, but hunting has ceased because of protection acts.

Life cycle

The life cycle is similar to that of an amphibious salamander except it does not terrestrialize and remains underwater during adulthood. Specifically the Japanese giant salamander travels up stream into the mountains to spawn and lay eggs

Egg (biology)

An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

. Larvae emerge from the eggs and lose their gills when they become adults.

Reproduction

Hynobiid salamanders practice external fertilization, or spawning. And, unlike other salamander families which reproduce internally, male hynobiids focus on egg sacs rather than females during breeding (Hasumi, 2002). The female lays two egg sacs at a time, each containing up to seventy eggs. Parental care is common.[1]
alternatively See Asiatic Salamander

Asiatic salamander

The Asiatic Salamanders are primitive salamanders found all over Asia, and in European Russia. They are closely related to the Giant Salamanders , with which they form the suborder Cryptobranchoidea. About half of hynobiids are unique to Japan .Hynobiid salamanders practice external fertilization,...

Cultural references

The Japanese giant salamander has been the subject of legend and artwork in Japan, for example in the ukiyo-e

Ukiyo-e

' is a genre of Japanese woodblock prints and paintings produced between the 17th and the 20th centuries, featuring motifs of landscapes, tales from history, the theatre, and pleasure quarters...

work by Utagawa Kuniyoshi.

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.