Chinese Giant Salamander

of Chinese giant salamander]] The correct scientific name of this species has been argued to be Andrias scheuchzeri (in which case Andrias davidianus would be a junior synonym) – a name otherwise restricted to an extinct species described from Swiss fossils. It has also been given the moniker of "living fossil" for being part of the family Cryptobranchidae which dates back 170 million years. A 2018 study of mitochondrial DNA revealed that there are five wild clades of the Chinese giant salamander, as well as two only known from captives (their possible wild range was previously unknown). They diverged from each other 4.71–10.25 million years ago and should possibly be recognized as cryptic species. Despite this deep divergence, they can hybridize among each other, and also with the Japanese giant salamander. In 2022, one of the captive-only clades was described as Andrias jiangxiensis, and was found to have maintained genetically pure wild populations in Jiangxi Province, in contrast to most of the other clades.

=== Diet === The Chinese giant salamander has been recorded feeding on insects, millipedes, horsehair worms, amphibians (both frogs and salamanders), freshwater crabs, shrimp, fish (such as Saurogobio and Cobitis ), and Asiatic water shrew. Based on a captive study, most activity is from the earlier evening to the early night. The Chinese giant salamander catches its prey on land with an asymmetrical bite, in such a way that the force created by their jaws will be maximized in the anterior region where their prey is located. After capture they use their bite to subdue and kill their prey, both on land and in water. They are missing a bone which usually lies along the upper cheek region of most salamanders, which gives them a much stronger bite force. The bite force of the adult Chinese giant salamander is much stronger than the bite force of the maturing Chinese giant salamander due to differences in cranial structure. Chinese giant salamanders esophaguses are made up of four different layers, one of which being a strong muscular tissue used to help move food through to the stomach. The outer most layer has ciliated cells that move mucous from mucous glands over the surface of the esophagus to lubricate it and reduce friction from large foods such as whole crabs. The ciliated structure and flexibility of the Chinese giant salamander's esophagus is hypothesized to be the reason why it is capable of swallowing such large foods. Chinese giant salamanders are also capable of fasting for several years if they need to. This is possible because of their metabolic reserves as well as their liver, which is capable of up regulating and down regulating certain proteins according to how long they have been fasting for.

Both sexes maintain a territory, averaging for males and for females. When laid, the eggs measure in diameter, but they increase to about double that size by absorbing water. When hatching, the larvae are about long and external gills remain until a length of about at an age of 3 years. Maturity is reached at an age of 5 to 6 years and a length of .

The Chinese giant salamander species complex comprises five clades, with multiple possibly worthy of species recognition. Their native ranges differ, but release of Chinese giant salamanders from captivity has complicated this picture. They were widespread in central, south-western, and southern China, although their range is now highly fragmented. A 2022 study identified one of the two clades known only from captivity as A. jiangxiensis, found in the wild only in Jiangxi Province. in captivity in AOAO Aquarium, Sapporo, Japan.]] Finds in Taiwan may be the result of introduction, though their exact taxonomic identity is unknown. The salamanders prefer to live in streams of small width (on average, across), quick flow, and little depth (on average, deep). Water temperature varies depending on season, with typical range at low elevation sites being from and at high elevation sites from .

=== Farming === Very large numbers are being farmed in China, but most of the breeding stock are either wild-caught or first-generation captive-bred. This is partially explained by the fact that the industry is relatively new, but some farms have also struggled to produce second-generation captive-bred offspring. Registrations showed that 2.6 million Chinese giant salamanders were kept in farms in 2011 in Shaanxi alone, far surpassing the entire countrywide wild population estimated at less than 50,000 individuals. Shaanxi farms (mainly in the Qinling Mountain region) accounted for about 70% of the total output in China in 2012, but there are also many farms in Guizhou and several in other provinces. Among 43 south Shaanxi farms surveyed, 38 bred the species in 2010 and each produced an average of c. 10,300 larvae that year. Farming of Chinese giant salamanders, herbs, and mushrooms are the three most important economic activities in Shaanxi's Qinling Mountain region, and many thousands of families rely on the giant salamander farms for income. The giant salamander farming mainly supplies the food market, but whether this can be achieved to an extent where the pressure on the wild populations is reduced is doubtful. Release of captive-bred Chinese giant salamanders is supported by the government (8,000 were released in Shaanxi in 2011 alone), but represent a potential risk to the remaining wild population, as diseases such as Ranavirus are known from many farms. The vast majority of the farmed Chinese giant salamanders, almost 80% based on a study published in 2018, are of Yellow River origin (the so-called haplotype B), although those from other regions also occur. Farms have generally not considered this issue when releasing giant salamanders and Yellow River animals now dominate in some regions outside their original range, further endangering the native types. Additionally, release of untreated wastewater from farms may spread diseases to wild Chinese giant salamanders.

]] As of early 2008, Species360 records show only five individuals held in US zoos (Zoo Atlanta, Cincinnati Zoo, and Saint Louis Zoological Park), and an additional four in European zoos (Dresden Zoo and Rotterdam Zoo); as well as one in the State Museum of Natural History Karlsruhe, where it is also the museum's mascot. As of 2019, London Zoo holds four individuals (one of them on display) that were seized from an illegal importation of amphibians in 2016. A medium-sized individual, approximately long, was kept for several years at the Steinhart Aquarium in San Francisco, California, and is now on display again in the "Water Planet" section of the new California Academy of Sciences building. There are also two in residence at the Los Angeles Zoo. Additional individuals are likely kept in non-Species360 zoos and animals parks in its native China, such as Shanghai Zoo. Several of them are kept in the aquaria of Shanghai and Xi'an. The Osaka Aquarium Kaiyukan in Japan has both a Chinese and a Japanese giant salamander on display, as does the Saitama aquarium in Hanyū, Saitama. The Ueno Zoological Gardens also has a Chinese giant salamander on display. Since May 2014, 33 Chinese giant salamanders, including three adults, have been held in Prague Zoo. The main attraction is the largest individual in Europe, which is long.

, China for 880 CNY/jin, or about 215 EUR/kg or US$127/lb. Such prices make them an attractive target for poaching.]] In the past, the Chinese giant salamander was fairly common and widespread in China. Its natural range has suffered in the past few decades due to habitat loss and overharvesting. Consequently, many salamanders are now farmed in mesocosms across China. Furthermore, previously built concrete dams that destroyed the salamander's habitat are now fitted with stairs so that the animal can easily navigate the dam and make it back to its niche. The Chinese giant salamander is listed as a critically endangered species. It has experienced a drastic population decline, which is estimated to be more than 80% in the last 3 generations and due to human causes. Human consumption is the main threat to the Chinese giant salamander. They are considered to be a luxury food item and source of traditional medicines in China.

, circa 3200 BC.]] According to a recent study, 90% of the Chinese giant salamanders' habitat was destroyed by the year 2000, Water pollution is also a great factor in the habitat destruction of the Chinese giant salamander; the immense decline in their population can be traced to, among the other major problems of over-hunting and failed conservation efforts, the tainting of the water that they live in. Mining activity in particular in areas near their streams often causes runoff that sullies the water, and farming—and all of the pesticides and chemicals that affect the soil that come with it—has a vastly negative effect on the areas near the streams as well. The presence of macronutrients in the streams can also cause algal blooms, which cloud the water and force the temperature to rise. The salamanders reside primarily in very cold underwater cavities and follow a specific nesting requirement, which means that they will only reproduce and care for their eggs in areas such as these, so changes in temperature are incredibly detrimental to their health and well-being as well as to their perpetuation as a species. These algal blooms also deplete the levels of oxygen in the water, and a lesser supply of oxygen can quite easily hold the potential to kill off many members of the dwindling species. Many efforts have been undertaken to create reserves and faux habitats for the Chinese giant salamander so that they can reproduce without worry of soiled water, but many of these reserves have failed in having a great impact overall due to the massive overhunting of the species. No matter how many members of the species they manage to save through the reserves, the poachers still manage to capture and kill that many more. Although habitat destruction is certainly not assisting in the perpetuation of the species, it is certainly not the biggest obstacle that the Chinese giant salamander faces in its quest to avoid extinction.

Like other amphibians, the Chinese giant salamander is ectothermic. Most Chinese giant salamanders stop feeding at water temperatures above and feeding ceases almost entirely at . Temperatures of are lethal to Chinese giant salamanders. As a consequence, the species is vulnerable to global warming.

One of the main reasons that the Chinese giant salamander, Andrias davidianus, has been placed on the critically endangered list by the International Union for Conservation of Nature is overhunting. 75% of native species in China are harvested for food. The salamander is also used for traditional medicinal purposes. In 1989, the Chinese government placed legal protection on the salamander (category II due to its population decline by The Wild Animal Protection Law of China and Appendix I in the Convention of Endangered Species of Wild Fauna.). But the salamander populations have continued to decline. The domestic demand for salamander meat and body parts greatly exceeds what can sustainably be harvested from the wild. Commercial captive breeding operations so far still rely on the regular introduction of new wild-caught breeding adults, because captive-bred animals have proven difficult to mate. In addition, salamander farms would need to increase their yield manifold before the black-market price of poached salamander drop significantly, meaning that a stricter enforcement of anti-poaching law is still very much the future for the Chinese giant salamander. China's penalty for illegally hunting these creatures is very low and only comes to 50 yuan, or about US$6, which is less than one hundred times the black-market price. Establishments such as restaurants can charge up to US$250–US$400 per kilogram. A hunting tool known as a bow hook is one of the preferred methods used by hunters to catch the salamander. This hunting tool is made with a combination of bamboo and sharp hooks baited with frogs or smaller fish. This is used to capture the salamander and keep it alive. Some hunters use pesticides to kill the salamander. Farmers often poach wild salamanders to stock their breeding programs, while others are hunted as food. In a 2018 study, the Zoological Society of London and the Kunming Institute of Zoology in China reported on their surveys for giant salamanders in 16 Chinese provinces over four years. The researchers had been unable to confirm survival of wild salamanders at any of the 97 sites they surveyed. The study also brought up worries that commercial farms and conservation programs were crossbreeding what they described as five distinct species of Chinese giant salamanders. All the wild populations studied were found "critically depleted or extirpated" by the study. A related study found that some of the five distinct genetic lineages were probably already extinct in the wild. However, the exhaustiveness of these surveys was questioned in a 2022 study by Chai et al., who noted that over a third of the surveys had been performed only in Guizhou Province, and another third of the surveys had been performed in provinces that were only selected by habitat suitability modeling and had no actual historic records of giant salamanders. Based on this, the extent of extirpation of Chinese Andrias remains uncertain, especially as a natural population of Andrias jiangxiensis was discovered during the Chai et al. study.