Salamanders are amphibians. They are lizard-like in shape, with long bodies and tails, and four legs that stick out to the sides of the body. Unlike lizards, they have soft, scale-less skin and soft shelled eggs that must be laid in water. Salamanders hatch as tadpoles with gills and metamorphose into their adult forms just as the frogs do. Like frogs, salamanders need a moist environment. Most are terrestrial as adults but a few, like the axolotl and the hellbender, spend their entire lives in an aquatic environment. Like frogs, there are no marine salamanders.
Salamanders are found in both North and South America, across Asia, Europe and Africa, but there are no known salamanders in Australia. This is interesting because Australia has lots of frogs. The Antarctic has no amphibians at all as amphibians do not cope well with extreme cold. This is because they are cold blooded (poikilothermic), like reptiles. There are about 500 species of salamanders world-wide.
Salamanders are usually about seven to 20 cm long, although a few can grow larger. The aptly named Japanese giant salamander can attain a length of 1.7 meters. Most salamanders are active at night, when they hunt for insects and other invertebrates. Most are dull in coloration but there are some brightly colored species. The adults have lungs but they can also respire through their moist skins because the skin is porous. This means they have to stay in a moist environment and cannot tolerate drying out and this is another reason for being active at night. Another reason is that they have few defenses against predators except to stay hidden under logs and in the leaf litter. In some countries, even humans eat salamanders.
A few salamander species are now kept as pets. One popular pet is the so-called Mexican walking fish or axolotl. It is not a fish at all but an amphibian. Unlike most salamanders, it does not lose its gills when it matures and never leaves the water. It makes an interesting pet.
There are 8 families of salamanders. The Hynobiidae or Asian land salamanders are the most primitive. Giant salamanders including the North American hellbender belong to the Cryptobranchidae. The axolotl is an example of the mole salamanders or Ambystomidae. A more normal example of this family is the marbled salamander. Members of this family are found in North America.
Newts and European fire salamanders belong to the family Salamandridae. In the Middle Ages, Europeans thought these salamanders could live in fire because they were often found in wood piles but like other salamanders, they cannot handle heat or desiccation. The largest family of salamanders, with almost 200 species, is the Plethodontidae or lungless salamanders. These small salamanders breathe entirely through their skin and mouths.
The last two families consist of species that permanently retain their larval forms: the mud puppies, Olmeidae; and the sirens, Sirenidae. The sirens are further distinguished by having no hind legs and crawl about using only their two forelegs.
Salamanders have interesting mating habits. Because the males have no copulatory organs, they deposit their sperm in front of the female that they have courted and she puts the sperm on her eggs. Salamanders make no noises so the males attract the females either by being brightly colored or by dancing or even hugging the females. Once the eggs are laid, there is usually no parental care, although in a few aquatic salamanders, the female will guard the eggs. The Japanese giant salamander is unique in that the male guards the eggs instead.
As well as using color to attract mates, some salamanders use it as a warning that their skin is poisonous, as a protection from predators. The black and yellow salamander of Europe and Asia oozes a poison from its skin when disturbed but this is not dangerous to humans.
For more information: http://animals.howstuffworks.com/amphibians/salamander-info.htm
