Italian crested newt Triturus carnifex

Description:

Salamanders are any of approximately 550 extant species of amphibians within the order Caudata.[1] They are typically characterized by a superficially lizard-like appearance, with slender bodies, short noses, and long tails. All known fossil salamanders and all extinct species fall under the order Caudata, while sometimes the extant species are grouped together as the Urodela.[2] Salamanders have never more than four toes on their front legs and five on their rear legs, but some species have fewer. 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. Many of the members of the family Salamandridae are known as newts. The earliest known salamander fossils have been found in geological deposits of China and Kazakhstan, which have been dated to the middle Jurassic period, up to 164 million (plus or minus 4 million) years ago.[3]

Habitat:

Mature salamanders generally have a basal tetrapod body form with a cylindrical trunk, four limbs and a long tail. Some species such as sirens and amphiumas have reduced or absent hindlimbs, giving them a more eel-like appearance. Most species have four clawless toes on the forelimbs and five on the hind limbs. The skin lacks scales and is moist and smooth to the touch, except in newts of the Salamandridae which may have velvety or warty skin that is wet to the touch. The skin may be drab or brightly colored, exhibiting various patterns of stripes, bars, spots, blotches or dots. Male newts become dramatically colored during the breeding season. Cave species dwelling in darkness lack pigmentation and have a translucent pink or pearlescent appearance.[4] Salamanders range in size from the minute salamanders, with a total length of 2.7 cm (1.1 in), including the tail, to the Chinese giant salamander which reaches 1.8 m (5.9 ft) and weighs up to 65 kg (140 lb). Most, however, are between 10 and 20 cm (3.9 and 7.9 in) in length. Respiration differs among the different species of salamanders. Species that lack lungs respire through gills. In most cases, these are external gills, visible as tufts on either side of the head, although the amphiumas have internal gills and gill slits. Some terrestrial salamanders have lungs used in respiration, although these are simple and sac-like, unlike the more complex organs found in mammals. Many species, such as the olm, have both lungs and gills as adults.[4] Some terrestrial species lack both lungs and gills and perform gas exchange through their skin, a process known as valerian respiration in which the capillary beds are spread throughout the epidermis, and inside the mouth. Even some species with lungs can respire through the skin in this manner. The skin of salamanders secretes mucus, which helps keep the animal moist when on dry land, and maintains their salt balance while in water, as well as providing a lubricant during swimming. Salamanders also secrete poison from glands in their skin, and some additionally have skin glands for secreting courtship pheromones.[4] Salamanders regularly shed the outer layer of their skin (the epidermis) as they grow, and then eat the resulting slough.[4][5][6]

Notes:

Terrestrial salamanders catch their prey by rapidly extending a sticky tongue which adheres to the prey, allowing it to be pulled into the mouth. In combination with tongue movements, salamanders may lunge forward and grasp prey with their jaws, securing them with small teeth on the margins of their jaws. In the lungless 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 a 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. Many of the highly aquatic species, however, lack muscles in the tongue, and do not use it for capturing prey, while most other species have a mobile tongue, but without the adaptations to the hyoid bone. Most species of salamander have small teeth in both the upper and lower jaws. Unlike frogs, even the larvae of salamanders possess these teeth.[4] To find their prey, salamanders use trichromatic color vision extending into the ultraviolet range, based on three photoreceptor types that are maximally sensitive around 450 nm, 500 nm and 570 nm.[7] Permanently subterranean salamanders have reduced eyes, which may even be covered by a layer of skin. The larvae, and the adults of some highly aquatic species, also have a lateral line organ, similar to that of fish, which can detect changes in water pressure. Salamanders have no external ear, and only a vestigial middle ear.[4] [edit]Defense Some salamander species use tail autotomy to escape predators. The tail will drop off and wriggle around for a little while, and the salamanders will either run away or stay still enough to not be noticed while the predator is distracted. Salamanders routinely regenerate complex tissues, including the lens or retina of the eye. Within only a few weeks of losing a piece of limb, a salamander perfectly reforms the missing structure. They can also produce a white, milky, poisonous substance.[8] [edit]