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Thursday, March 27, 2003


Black salamander

* Japanese name: Kuro sansho uo
* Scientific name: Hynobius nigrescens
* Description: Salamanders are considered primitive amphibians in comparison to frogs and toads. Like all amphibians, however, salamanders spend their lives in two entirely different states. The larvae are aquatic, breathing water through gills, and the adults are terrestrial, breathing air through lungs. Adults have smooth, glossy, black-spotted brown skin and are 12-20 cm long.
* Where to find them: Black salamanders belong to a family of salamanders (the Hynobiids) whose distribution is entirely Asian. In Japan they can be found in and around streams and bodies of water in mountainous regions of Honshu. Adult black salamanders hibernate in winter and enter the water only to breed. Reproduction is external: Females spawn a mass of eggs (said to resemble Japanese gravestones in shape), and then males scramble to fertilize them. The successful male releases sperm on top of the eggs. By May, the larvae are 4-5 cm long, and their front and back legs are starting to sprout from their bodies (see photo). Unlike frogs and toads, salamanders retain their tails in the adult state.
* Food: Adults will eat most things they can fit into their mouths, including worms, insects, slugs and even small mice, if they can catch them. Larvae eat insect larvae, freshwater snails and tadpoles.
* Special features: Some salamanders have more DNA than us. Humans have 23 pairs of chromosomes, making 46 in total. (Chromosomes are the structures in our cells where our DNA, our genetic material, is stored.) Yet some salamanders in the Hynobiid family have 62 chromosomes in total. Geneticists have yet to decide exactly why they need so much DNA, but it is thought that the large number of chromosomes, and certain other features (such as the presence of an angular bone in the lower jaw) indicate that Hynobiids are primitive, resembling the ancestral form of all salamanders. Remarkably, there have been reports of parental care of eggs by male black salamanders. Apparently, males defend the fertilized egg mass (a tasty, nutritious snack for many animals) against predators.

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