The Chinese giant salamander, or Andrias davidianus, is the one of the largest amphibians in the world. Its' classification is as follows:
The Cryptobranchid family encompasses three species of giant salamander, all of which are among the largest in the world. Andrias davidianus lives in the mountain streams of China at elevations below 1,500 feet. More specifically, one may find a Chinese giant salamander in the Yangtze, Yellow,and Pearl Rivers and their tributaries. This species prefers cold, fast running mountain streams and lives in muddy, dark rock crevices. It is also a nocturnal species, preying on its food mostly at night. Due to over exploitation and fragmentation of their environment, the Chinese giant salamander is currently listed as critically endangered by the IUCN (International Union on Conservation of Nature). The Yangtze River basin alone is home to 480 million people, or nearly one third of China’s total population. The high density of humans in this basin puts added stress on the river systems, which need to be protected in order to save the Chinese giant salamander. Because of the growing population, the Chinese giant salamander is loosing valuable habitat, and the habitat it does have left is becoming polluted. Overhunting also poses a major threat to this species as it is considered a Chinese delicacy.
Another recent possible factor contributing to the decline of this species is the iridovirus. During the summer months in 2010, researchers raising populations of Andrias davidianus in China in mountain caves and ditches for conservation reasons found a 95% mortality rate in one group. More specifically, the most affected populations were those living in ditches. Some effects of the iridovirus include swelling, emaciation, ulcers and erythema on the dorsal and ventral body surfaces, toe necrosis, darkened livers, and lesions on the kidney and spleen. Scientists were able to isolate the iridovirus from the liver and spleen to better examine it. Researchers attempted to intervene by giving antimicrobial drug treatments, but they proved unsuccessful. They suggested that living in the cooler cave environments might be a better alternative than the ditches because ambient temperatures are cooler in the caves. One additional way to slow down the epidemic of the iridovirus, especially in the summer months, is to limit the species contact with other animals known to carry the disease to decrease the chances of horizontal transmission. Other animals that have the ability to carry the disease include the Chinese forest frog and gopher tortoises. By keeping these populations of Andrias davidianus isolated from possible carriers and in cooler environments, this iridovirus epidemic may be controllable.
The Chinese giant salamander is the largest species of salamander ranging in size from 1 meter to 1.8 meters in length, although they seem to be getting smaller in size due to over harvesting and exploitation of their environment. No only are they long, they are also heavily built with a dorso-ventrally flattened head as well as short and flattened legs. They have small eyes and rely mostly on sensory organs to sense water and prey movement. This species is unique in that it is fully aquatic with many adaptations for this lifestyle. This salamander uses its skin for respiration, which is specialized in that it is rough, highly vascular, porous, and has folds to increase oxygen absorption. The Chinese giant salamander can range in color from dark brown to black or green and further characterized by having blotchy patches of color. They also have small, paired tubercles arranged in rows parallel to the lower jaw, which contain neuromasts to detect water and prey movement to aid in feeding. These neuromasts are mechanoreceptive organs which allow the organism to sense mechanical changes in the water. The Chinese giant salamander uses these mechanoreceptors to feed on smaller salamanders, worms, insects, crayfish, and snails. It catches its pray by snatching them with a rapid sideways snap of the mouth. Its only real predator is the human species as we over-harvest them for the food trade.
The Chinese giant salamander has an interesting evolutionary history seeing as there are only three species in the Cryptobranchid family. The common ancestor of this family diverged from all other amphibians more than 170 million years ago sometime during the Jurassic Period. This is unique in that it is one of the longest unbroken lineages among modern species such as the caecilians, salamanders, frogs, and toads. The Cryptobranchids are thought to have evolved from primitive salamanders primarily found in Asia. Because there is only three species within this family, it is imperative that conservation efforts are put forth to preserve the biodiversity in regions where these species live.
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