By st20113 
Introduction
The Tiger Salamander (Ambystoma tigrinum) is one of the largest land-dwelling salamanders in North America, named for the bold yellow or olive blotches and stripes that pattern its dark body. It ranges from the Atlantic coast to the Rocky Mountains and from southern Canada to northern Mexico, yet it is seldom seen, because adults spend most of their lives in underground burrows, emerging mainly on rainy nights and during the spring breeding migration.
Some populations never leave the water at all, retaining their larval gills and aquatic lifestyle for life, a condition called neoteny that is also seen in its close relative the Axolotl.
Taxonomy
The Tiger Salamander belongs to the family Ambystomatidae, the mole salamanders of North America, within the genus Ambystoma. It is closely related to the California Tiger Salamander (A. californiense) and the Blue-spotted Salamander (A. laterale), with which it hybridises where ranges overlap. Genetic studies suggest that the species as currently defined may actually contain several distinct lineages, and some researchers argue that the western form A. t. mavortium deserves full species status.
Physical Characteristics
Adults typically measure 15 to 35 centimetres, making the Tiger Salamander among the largest of truly terrestrial salamanders; only the giant aquatic Hellbender is bigger in North America. The body is stout, with a broad head, smooth moist skin, and dark brown, olive, or black colouration boldly marked with yellow or orange. Front feet bear four toes and hind feet five, ideal for digging. Like all ambystomatids, it has no lungs and breathes through its skin and mouth lining, so it must stay moist; the flattened tail aids swimming in larvae and stores fat in adults.
Habitat
Tiger Salamanders occupy an extraordinary range of habitats, from eastern deciduous forests and Great Plains grasslands to southwestern deserts and montane pine forest, but all share one essential requirement: shallow, fish-free ponds or vernal pools for breeding, because fish would devour their eggs and larvae. Adults are fossorial, digging burrows with their snouts and forelimbs or taking over rodent tunnels. Vernal pools, which fill in spring and dry by summer, are ideal breeding sites, since their temporary nature keeps fish out, and they support the aquatic invertebrates on which the larvae feed.
Diet
The Tiger Salamander is a voracious carnivore. Adults eat earthworms, slugs, snails, beetles, crickets, centipedes, and spiders, and large individuals also take mice, small frogs, and even other salamanders. Aquatic larvae consume mosquito larvae, water fleas, tadpoles, and small fish, and both stages are opportunistic cannibals when prey runs short. Hunting depends mainly on smell: a well-developed vomeronasal organ detects chemical cues in soil and water, making the salamander an effective hunter in the darkness of burrows and leaf litter.
Reproduction
Breeding begins in early spring, when warming rains fill the breeding ponds and adults migrate from their burrows, sometimes travelling more than a kilometre. Males arrive first and court females with circling displays, waving their tails to waft pheromones through the water. Females attach gelatinous egg masses, each holding 100 to 500 eggs, to submerged vegetation or rocks. Larvae hatch in two to four weeks and stay aquatic for two to five months before metamorphosing; in permanent ponds, some delay metamorphosis and breed while still gilled and aquatic.
Conservation
The IUCN lists the Tiger Salamander as Least Concern, and it remains one of the most widespread salamanders in North America. Even so, local populations have disappeared across parts of the northeastern United States owing to habitat loss, the drainage of vernal pools, pollution, road mortality during spring migrations, and the introduction of fish into historically fishless wetlands. Conservation measures include protecting breeding pools, building under-road tunnels and culverts for migrating adults, and captive breeding and reintroduction programmes where populations have been lost.
Fun Facts
Tiger Salamanders are extraordinary survivors: individuals have lived more than 25 years in the wild, brumate underground through winter on fat stored in their tails, and can survive days submerged in frozen water by slowing their metabolism. The species is the state amphibian of Kansas and Illinois. In the laboratory it is a celebrated model for regeneration research, regrowing lost limbs, tail sections, and even parts of its heart and brain with remarkable precision, a capacity that continues to inspire studies of tissue repair.