Referat The Japanese Giant Salamander

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The Japanese Giant Salamander The Giant Salamanders, the largest living amphibians, belong to family Cryptobranchoidea (interesting name, isn’t it?). In spite of this giant salamanders are significantly less known by the large public than their analogous in reptiles’ world, the Komodo Dragons. The family Cryptobranchoide has two genus with one (Cryptobabranchus alleganiensis) respectively two species (Andrias davidianus, A. japonicus). A. japonicus is restricted to Japan, A. davidianus in China while C. alleganiensis lives in North America. A. japonicus lives in the cold fast flowing mountain streams and smaller rivers of Kyushu Island and western Honshu in Japan. Thirty million years old fossilized Giant Salamanders have been found in Europe as well. The giant salamanders are considered true “biological relicts”. Leading scientists admit that they did not evolve in the last 20-30 million years. For scientist these rather primitive salamanders are clues to the understanding of the roots of Earth’s biodiversity. As their way of life has not changed significantly students of Giant Salamanders may provide insightful information on the ecosystems that existed million years ago. In spite of their relatively large body size and somewhat frightening looks they are totally harmless to humans. Unfortunately the opposite is not true. Both A. japonicus and A. davidianus are threatened with extinction. Until the early 50’s Japanese Giant Salamanders were an important protein source for the local population. They were caught by fishing rod and were considered a true delicatessen. Accelerated degradation of natural habitats represents today a bigger threat to the Giant Salamanders that hunting, or illegal killing by fishermen. Being old species Giant Salamanders might lost their genetical plasticity. It is well known that the older a species is the harder it adapts to new conditions. A. japonicus is considered an important environmental symbol. Many aspects of their life have not been elucidated, yet. A surprisingly small amount of scientific papers deal with them. Partly because of their restricted spreading area, partly because their size. Scientist face much more ethical issues with larger species than with the smaller ones. The risk of extinction and the limited spreading area rises even more the moral and ethical problems. The financial efforts are considerable as well. Biology of Andrias japonicus A. japonicus lives to the age of 50 years, growing continuously throughout their lives they may reach a body size of 150 cm and a body weight of 25-30 kg. They can breathe both on land and in water. The skin that absorbs oxygen direct from the water allows them to stay immersed for longer periods. Unlike most salamanders they never leave the aquatic habitat. Japanese Giant Salamanders represent the top of river’s ecosystems, and eating almost anything they can catch (from insects to fish to mice to small invertebrates like crabs), without having any natural predators. Giant Salamanders have a very slow metabolism, and can go weeks without eating, if necessary. Catching fish they concur with local fishermen who respond by killing specimens and destroying habitats. Japanese Giant Salamanders begin reproduction in late August, when herds congregate at nest sites. Males compete, viciously, with many dying due to wounds from fights. Females lay between 400 and 500 eggs in the fall, which may be fertilized by several males. Males aggressively guard the nests, which may contain eggs from several females, until they hatch in the early spring. PAGE PAGE 1 쥁`