Description[change | change source]
Eastern tiger salamanders are big, with a normal length of 6–8 inches (15–20 cm). They can grow up to 14 inches (36 cm) in length. Grown-ups are usually spotted with grey, green, or black, and have large eyes. They have short mouths, big necks, strong legs, and long tails. They eat small insects and worms. Sometimes, grown ups eat small frogs and baby mice
Adults are almost never seen in open fields and often live in holes that are usually 2 feet from the top. Tiger salamanders almost always stay on land as adults, and usually only return to the water to lay eggs. But also they live in both land and water. They also like to swim, even if they are on land. They also are good swimmers. Like all ambystomatids, they are extremely loyal to their birthplace, and will travel long distances to go back. However, a single tiger salamander has only a 50% chance of laying eggs more than once in its lifetime. Males bump a 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 gills on the outside and a big tail fin that begins just behind the head. Arms are grown within a short time of coming out of their egg. Some larvae, especially in pools that are here one season and gone the next 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 many times 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[change | change source]
While remaining common in many places, Tiger Salamander numbers have gone down compared with old levels. One of the largest threats to Tiger Salamander populations is wetland (habitat) destruction and/or changing. Since they tend to breed in semipermanent wetlands, baby Tiger Salamanders often experience mass deaths in association with pond drying. Fishes that have moved to their ponds have also been known to reduce, and levels they also experience reduced growth and longer larval periods. The effect of agricultural pesticides in urine disruption has also been researched. All of these issues have changed 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 North and South Carolina. (http://www.amphibiaweb.org) In November 2001, the Canadian Species at Risk Act listed the Great Lakes number of the Tiger Salamander as being removed, 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[change | change source]
The California Tiger Salamander (Ambystoma californiense), the Barred Tiger Salamander (Ambystoma mavortium), and the Plateau Tiger Salamander (Ambystoma velasci), were all once subspecies of A. tigrinum, but are now separate species. Genetic studies made it right to break up the first 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, keeping most characteristics of their larval stage for their entire lifespan. While they never change under natural conditions, metamorphosis can be programmed in them, resulting in a form very similar to the Mexican Tiger Salamander. This is not, however, their natural condition, and shortens their lifespan by a lot.
References[change | change source]
- Hammerson et al. (2004). Ambystoma tigrinum. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. 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