Chinese giant salamander

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Zoology with: Chinese giant salamander

The Chinese giant salamander is the largest living species of amphibian, reaching a maximum length of 1.8 metres. It lives in cool, fast-flowing streams and mountain lakes and predominantly feeds on fish and crustaceans. The breeding season occurs between August and September when 500 eggs are laid in a burrow guarded by the male. This species is threatened by over-harvesting for the food trade, as well as the destruction and degradation of its habitat. It is now Critically Endangered, having undergone a massive population decline over the last 30 years.

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Evolutionary Distinctiveness
Order: Caudata
Family: Cryptobranchidae
There are only 3 living species of giant salamander in the family Cryptobranchidae. Ancestors of the Cryptobranchidae diverged from all other amphibians over 170 million years ago during the Jurassic Period, which makes this family of amphibians one of the longest unbroken lineages present amongst the modern species assemblages of caecilians, salamanders, frogs and toads. The genus Andrias is represented by only 2 extant species.Cryptobranchids are believed to be derived from hynobiid-like amphibians (relatively primitive small- to medium-sized salamanders found primarily in Asia) due to the retention of larval characters into adulthood (a process called “neoteny”). The fossil record of cryptobranchid salamanders begins with Cryptobranchus saskatchewanensis from the Upper Paleocene to the Lower Eocene (52-58 million years ago), Cryptobranchus scheuchzeri from the Middle Oligocene to the Upper Pliocene in Europe (2-33 million years ago), and Cryptobranchus matthewi from the middle Miocene to the Miocene-Pliocene boundary (14-21 million years ago). The American hellbender Cryptobranchus alleganiensis is also known from the Pleistocene of North America (up to 1.8 million years ago), and the Japanese giant salamander Andrias japonicus is known from the Pleistocene of Asia (1.8 million years ago).
Description
The permanently aquatic Chinese giant salamander is heavily built, with a flat, broad head and a truncated snout. It has a wide mouth, small round eyes that lack eyelids, and small, rounded nostrils close to the edge of the upper lip at the corners of the snout. The species has a large tongue and possesses vomerine teeth (two small bumps found on the roof of the mouth or palate) in addition to a long arc of maxillary (or jaw) teeth.
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The body, like the head, is quite flattened in appearance, with a broad, compressed tail almost 60% of the body length. The species has a series of costal grooves (found along the sides of the body in the region of the ribs), as well as a vertebral groove (running along the back) and a fold of skin present along the sides of the body from the back of the head to the tip of the tail. The skin is generally rough and porous with numerous wrinkles, folds and tubercles (small bumps). Individuals are dark brown, black or greenish in colour with irregularly blotched, marbled or and/or spotted patterning.Total body length at adulthood is about 1 metre, although a classic publication on the Chinese salamander by M.L.Y. Chang in 1936 quotes a maximum length of 180 cm (1.8 metres). Individuals of 115 cm weigh over 11 kg. This makes the Chinese giant salamander the largest extant amphibian species in the world, both in terms of length and mass, although its close relative the Japanese giant salamander can also reach lengths of 1 m. However, due to wild harvesting of the Chinese giant salamander as a delicacy in Asia, most animals found today are considerably smaller.
Ecology
The breeding season for Chinese giant salamanders appears to occur between August and September. Mating behaviour described for Japanese giant salamanders is probably similar for the Chinese giant salamander. Females lay a string of approximately 500 eggs (each measuring on average 22 mm by 19.2 mm, with an embryo diameter of 8-9 mm) in an underwater burrow or “breeding cavity” that is occupied by a male. The occupying male will aggressively guard this breeding cavity against any intruders. Females may enter the cavity and leave it directly after spawning. Eggs are fertilised externally and then guarded by the male until they hatch after 50-60 days.Chinese giant salamander larvae resemble the adults in shape, and develop in streams. They are only 30 mm in length upon hatching, and start eating after about 30 days. The external gills of the larvae start to reduce in size when they measure 200-250 mm in length, although adults never fully lose two of their gill branches. The larvae have longer gills than those of Japanese giant salamander, their fingers and toes are more pointed, and they are darker in colour. Chinese giant salamanders are very long-lived, reaching ages of more than 52 years in captivity, and are thought to reach sexual maturity at around 15 years.The Chinese giant salamander is generally nocturnal, although they become more diurnal during the breeding season. During the day, the species will usually be found in dark hiding places, venturing out only to stalk their prey and feed. They feed on a wide variety of prey items, such as fish, worms, insect larvae, anurans (frogs and toads) and their tadpoles, crustaceans, molluscs, aquatic reptiles and small mammals. Chinese giant salamanders are also known to eat carrion, their own shed skin and eggs, and may also exhibit cannibalistic behaviour. However, usually the majority of the adult’s diet will simply consist of crustaceans and fish. Chinese giant salamander teeth are small but numerous. The bite is very powerful and provides a strong grip on their prey. The fusion point of the upper and lower jaw of this species is flexible, with large bundles of elastic cartilage that allow the gape of the mouth to reach 40°. The feeding method employed in this species is known as asymmetrical buccal suction, where the lower jaw is depressed quickly and nearby prey items are sucked into the mouth. They have very small eyes positioned far back on the sides of their head that provide them with poor vision – both eyes cannot focus on the same object at the same time. They therefore rely heavily of smell and touch to find their prey.

Chinese giant salamanders possess lungs, though which they are able to breathe inefficiently, but they primarily take up oxygen from the water through their skin. As their larval gills become reduced, adults develop a conspicuous fold of skin along their flanks to increase the surface area for oxygen uptake. Their large size, lack of gills and inefficient lungs confine this species to flowing water.

Habitat
The habitat of the Chinese giant salamander consists of rocky, mountain streams and lakes with clear, fast-running water. The species is usually found in forested areas at moderate altitudes, below 1500 m above sea level and especially between 300 and 800 m. Chinese giant salamanders occupy underwater hollows and cavities, and spend their whole lives in water.
Distribution
The Chinese giant salamander is widespread in central, south-western and southern China, although its range is now very fragmented. It occurs from 100–1,500 m above sea level in the mountain stream tributaries of the Pearl, Yellow and Yangtze Rivers. The species ranges from Qinghai and Sichuan to Guangxi, Guangdong and Jiangsu provinces. The population in Taiwan has probably been introduced from mainland China.
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— original source http://www.edgeofexistence.org/amphibians —
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