Salamander (orig. from Persian: s?m, "fire", and andar?n, "within") is the common name for a group of approximately 500 species of amphibians typically characterized by slender bodies, short legs, and long tails. They have four front toes and their hind legs have five. Their moist skin usually makes them reliant on habitats in or near water or under some protection on moist ground, often in a swamp. Some salamander species are aquatic throughout life, some take to the water intermittently, and some are entirely terrestrial as adults. They lay eggs in water. Uniquely among vertebrates, they are capable of regenerating lost limbs, as well as other body parts, in a process known as ecdysis.
Respiration differs among the different species of salamanders. In those that lack lungs, respiration is done through the gills as water passes over the gill slits. Some salamanders that are terrestrial have lungs that are used in respiration similar to that in mammals. However, some terrestrial species lack both lungs and gills and perform gas exchange through their skin, a process known as valarian respiration in which the capillary beds are spread throughout the epidermis, including inside the mouth.
Hunting is yet another unique aspect of salamanders. Muscles surrounding the hyoid bone contract to create pressure and actually "shoot" the hyoid bone out of the mouth along with the tongue. The tip of the tongue is composed of mucus which creates a sticky end to which the prey is captured. Muscles in the pelvic region are used in order to reel the tongue and the hyoid back to its original position.
Salamanders split off from the other amphibians during the Mid to Late Permian, and initially were similar to modern members of the Cryptobranchoidea. Any resemblance to lizards is the result of convergence of the basic tetrapod body plan, as they are no more closely related to lizards than they are to mammals. Their nearest relatives are the frogs and toads, within Batrachia.
Species of salamanders are numerous and found in most moist or arid habitats in the northern hemisphere. The salamander is the largest amphibian in the world. They usually live in or near brooks,creeks,ponds and other moist locations. Many are relatively small, but there are definite exceptions. North America hosts the hellbender, the eastern tiger salamander, and the mudpuppy which can reach the length of a foot (30 cm) or more. In Japan and China the giant salamander is found, which reaches 6 feet (1.8 m) and weighs up to 30 kilograms.. There are ten families belonging to the order Urodela, divided into three suborders:
The life history of salamanders is similar to other amphibians such as frogs. The life cycle begins with an egg stage, usually laid the previous winter in a pond. A larval stage follows in which the organism is fully aquatic. Depending on species, the larval stage may or may not possess legs. The salamander possesses gills at this point. Some species (such as Dunn's Salamander (Plethodon dunni)) of salamander exhibit no larval stage. Neoteny has been observed in all salamander families, in which an individual may retain gills into sexual maturity. This may be universally possible in all salamander species. More commonly, however, metamorphosis continues with the loss of gills, the growth (or increase in size) of legs, and the capability of the animal to function terrestrially.
Numerous legends have developed around the salamander over the centuries, many related to fire. This connection likely originates from the tendency of many salamanders to dwell inside rotting logs. When placed into a fire, the salamander would attempt to escape from the log, lending to the belief that salamanders were created from flames - a belief that gave the creature its name.
Associations of the salamander with fire appear in the Talmud and the Hadith, as well as in the writings of Conrad Lycosthenes, Benvenuto Cellini, Ray Bradbury, David Weber, Paracelsus and Leonardo da Vinci.