Tiger Salamander

Tiger Salamander
Tiger Salamander (Ambystoma tigrinum)
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Amphibia
Subclass:	Lissamphibia
Order:	Caudata
Family:	Ambystomatidae
Genus:	Ambystoma
Species:	A. tigrinum
Binomial name
Ambystoma tigrinum Green, 1825

The Tiger Salamander (Ambystoma tigrinum) is a species of Mole Salamander. The proper common name is the Eastern Tiger Salamander, to differentiate from other closely related species.

Description

Eastern tiger salamanders grow to a typical length of 6–8 inches (15–20 cm). They can reach up to 14 inches (36 cm) in length, particularly neotenic individuals. Adults are usually blotchy with grey, green, or black, and have large, lidded eyes. They have short snouts, thick necks, sturdy legs, and long tails. Their diet consists largely of small insects and worms, though it is not rare for an adult to consume small frogs and baby mice.

Adults are rarely seen in the open and often live in burrows that are usually 2 feet from the surface. Tiger salamanders are almost entirely terrestrial as adults, and usually only return to the water to breed. But also they partly live in both land and water. Although Tiger Salamanders are terrestrial, they are good swimmers. Like all ambystomatids, they are extremely loyal to their birthplace, and will travel long distances to reach it. However, a single tiger salamander has only a 50% chance of breeding more than once in its lifetime. Males nudge a willing female to initiate mating, and then deposit a spermatophore on the lake bottom. The female picks up the packet and deposits the now-fertilized eggs on vegetation. Large-scale captive breeding of Tiger salamanders has not been accomplished, for unknown reasons.

The larvae are entirely aquatic, and are characterized by large external gills and a prominent caudal fin that originates just behind the head. Limbs are fully developed within a short time of hatching. Some larvae, especially in seasonal pools and in the north, may metamorphose as soon as feasible. These are known as small morph adults. Other larvae, especially in ancestral pools and warmer climates, may not metamorphose until fully adult size. These large larvae are usually known as waterdogs, and are used extensively in the fishing bait and pet trade. Some populations may not metamorphose at all, and become sexually mature while in their larval form. These are the neotenes, and are particularly common where terrestrial conditions are bad.

Diseases

Although immune themselves, Tiger Salamanders transmit Batrachochytrium dendrobatidis, which is a major world-wide threat to most frog species through the disease Chytridiomycosis.^[1] Tiger Salamanders also carry ranaviruses which infect reptiles, amphibians, and fish. Using Tiger Salamander larvae as fishing bait appears to be a major source of exposure and transport to wild populations. Severe mortality of Tiger Salamander larvae sometimes occurs from recurring ranavirus infections.

Relative species

The California Tiger Salamander (Ambystoma californiense) (listed at Vulnerable) ^[2] , the Barred Tiger Salamander (Ambystoma mavortium), and the Plateau Tiger Salamander (Ambystoma velasci), were all once subspecies of A. tigrinum, but are now considered separate species. Genetic studies made it necessary to break up the original A. tigrinum population, even though there is some hybridization between groups.

The Axolotl is also a relative of the Tiger Salamander. Axolotls live in a neotenous state, retaining most characteristics of their larval stage for their entire lifespan. While they never metamorphose under natural conditions, metamorphosis can be induced in them, resulting in a form very similar to the Mexican Tiger Salamander. This is not, however, their natural condition, and dramatically shortens their lifespan.

References

1. ^ "Petwatch". Exotics as Pets. http://www.petwatch.net/browse_animals/amphibians/6-tiger_salamander. 
2. ^ "Ambystoma californiense". IUCN Red List. http://www.iucnredlist.org/apps/redlist/details/1098/0. 

• The IUCN Red List of Threatened Species: Ambystoma tigrinum
• LeClere, 2006 Iowa Herpetology Species account, photo and range map of the Tiger Salamander in Iowa
• EcoHealth Alliance, Disease Transmission

External links

• Tiger Salamander at the Encyclopedia of Life
• Tiger Salamander (Ambystoma tigrinum), Natural Resources Canada
• http://www.petwatch.net/browse_animals/amphibians/6-tiger_salamander