Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant species are grouped together as the Urodela. Most salamanders have four toes on their front legs and five on their rear legs. Their moist skin usually makes them reliant on habitats in or near water, or under some protection (e.g., moist ground), often in a wetland. Some salamander species are fully aquatic throughout life, some take to the water intermittently, and some are entirely terrestrial as adults. Unique among vertebrates, they are capable of regenerating lost limbs, as well as other body parts.
Mature salamanders generally have a primitive tetrapod body form similar to that of lizards, with slender bodies, long tails, and four limbs. However, like some lizards, many species of salamander have reduced or absent limbs, giving them a more eel-like appearance. Most species have limbs with four toes on the forelimbs, and five on the hind limbs, and lack claws. Salamanders are often brightly colored, either in both sexes throughout the year, or only in the males, especially during the breeding season. However, the species dwelling entirely underground are often white or pink, lacking any skin pigment.
Many salamanders are relatively small, but there are definite exceptions. They range in size from the minute salamanders, with a total length of 2.7 centimetres (1.1 in), including the tail, to the Chinese giant salamander which reaches 1.8 metres (5.9 ft) and weighs up to 65 kg (140 lb). Most, however, are between 10 centimetres (3.9 in) and 20 centimetres (7.9 in) in length. Salamanders regularly shed the outer layer of their skin (the epidermis) as they grow, and then eat the resulting slough.
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