Tailed amphibian of the order Urodela. They are sometimes confused with lizards, but unlike lizards they have no scales or claws. Salamanders have smooth or warty moist skin. The order includes some 300 species, arranged in nine families, found mainly in the northern hemisphere. Salamanders include hellbenders, mudpuppies, olms, waterdogs, sirens, mole salamanders, newts, and lungless salamanders (dusky, woodland, and spring salamanders).

They eat insects and worms, and live in water or in damp areas in the northern temperate regions, mostly feeding at night and hiding during the day, and often hibernating during the winter. Fertilization is either external or internal, often taking place in water. The larvae have external gills. Some remain in the larval form, although they become sexually mature and breed; this is called neoteny. The Mexican axolotl and the mud puppy Necturus maculosus of North America are neotenic.

In 1998, five new salamander species were discovered in tropical east-central Mexico. The species all belong to the genus Thorius, whose members are characterized by their smallness – some species are less than 2 cm/0.8 in length.

I saw them taken from the Mekong. Some were quite large and aggressive.