| Tiger Salamander | ||||||||||||||||
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| Ambystoma tigrinum Green, 1825 |
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The Tiger Salamander (Ambystoma tigrinum) is a species of Mole Salamander. The proper common name is the Eastern Tiger Salamander, as to differentiate from other closely related species.
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Description
Eastern tiger salamanders are large, with a typical length of 6-8 inches. They can reach up to 14 inches in length, particularly neotenic individuals. Adults are usually blotchie 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 usally 2 feet from the surface. Tiger salamanders are almost entirely terrestrial as adults, and usually only return to the water to breed. Like all ambystomatids, they are extremely loyal to their birthplace, and will travel 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. Larvae come in two types - cannibalistic and non-cannibalistic. High larvae density is said to trigger the cannibalistic phenotype,citation needed which has a much larger head than normal. 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.
Conservation status
While remaining locally common in many regions, Tiger Salamander numbers have declined compared with historical levels. One of the largest threats to Tiger Salamander populations is wetland (habitat) destruction and/or alteration. Since they tend to breed in semipermanent wetlands, larval Tiger Salamanders often experience mass mortality in association with pond drying. Introduced fishes have also been known to reduce, and\levels they also experience reduced growth and longer larval periods. The effect of agricultural pesticides in endocrine disruption has also been researched. All of these issues have collectively influenced Tiger Salamander populations. However, Tiger Salamanders are only listed as endangered in Delaware, New York, New Jersey and Maryland; protected in Arizona; and of special concern in both NortBold texth and South Carolina. (http://www.amphibiaweb.org) In November 2001, the Canadian Species at Risk Act listed the Great Lakes population of the Tiger Salamander as being extirpated, and the Southern Mountain population in British Columbia's Okanagan as endangered in Canada.
Tiger salamander adults are also often sold as pets, or used in research. Nearly all such salamanders are wild-caught.
Relative species
The California Tiger Salamander (Ambystoma californiense), the Barred Tiger Salamander (Ambystoma mavortium), and the Mexican 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.
References
- Hammerson et al (2004). Ambystoma tigrinum. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006. Database entry includes a range map and justification for why this species is of least concern.
- LeClere, 2006 Iowa Herpetology Species account, photo and range map of the Tiger Salamander in Iowa
External links
Information related to Ambystoma tigrinum from Wikispecies.
Media related to Ambystoma tigrinum at Wikimedia Commons- Tiger Salamander at the Encyclopedia of Life
Wikipedia content modification information:
- This page was last modified on 9 December 2008, at 01:50.
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