Distinguishing features
The Tiger Salamander is the most widespread salamander species in North America and is one of the few that is capable of tolerating the dry conditions of many regions in the interior of North America. It is extremely variable in its markings and many subspecies are recognized. This is a large salamander that is smeared with yellow and black to form irregular blotches or vertical stripes. Two tubercles are present on the sole of each foot. There are no parotoid glands present.
The Tiger Salamander in British Columbia has large blotches of yellow or dirty white on a black, grey or dark brown background. The borders of the blotches are often indistinct or they might join in such a way as to form a zebra-like pattern. The blotches extend down the sides and are not confined to the back nor do they ever form a distinct dorsal stripe. The belly is dirty grey while the legs and tail are mottled with light and dark patches.
The head of the Tiger Salamander is round and relatively short but may have a pronounced snout. The eyes are fairly small and are widely spaced on the sides of the head. There are usually 13 costal grooves on the sides of the body. The well-developed legs overlap by three or four costal grooves when adpressed along the body. Each foot has two tubercles on the sole. Males have slightly longer tails than females and have swollen vents in the breeding season. Adult Tiger Salamanders may be as much as 200 mm long but generally average between 140 and 180 mm; the tail makes up about half this.
The larvae of the Tiger Salamander are pond-type and have large gills and tail fins. The head is
depressed and the eyes are rather small. The larvae of Tiger Salamanders may reach 75 to 80 mm
before transforming. Paedogenic adults are sometimes called "mud puppies" and can reach lengths
exceeding 20 cm. Neotenic individuals may occur in some localities, especially in deeper ponds or
lakes.
Salamanders possess a unique life-preserving characteristic. It can anticipate and respond to changes in the environment that threaten its survival. Whilst other animals around the Salamander become the victims of these changes, the Salamander has the capability to physically transform itself from a fish to a land-based animal. It equips itself to escape and thrive in a new and unfamiliar terrain.
BARRED TIGER SALAMANDER Ambystoma tigrinum mavortium
Description The Tiger Salamander is the largest land-dwelling salamander in the world. The Barred Tiger Salamander typically grows from six to eight and one half inches. It has 11 to 14 costal grooves on its body. Overall, the body is dark brown to black with yellow bars and spots giving it the "tiger-stripe" look.
Life History These large salamanders make a nice meal for many animals such as snakes, turtles, herons and fish. They, in turn, may predate on insects, earthworms, small mice and even other amphibians. Barred Tiger Salamanders best avoid predators by a nocturnal and secretive lifestyle. They are active under the cover of darkness and spend most of their time in underground burrows or in thick vegetation near water. This salamander may take cover in mammal burrows or, if the soil is soft enough, they will dig out their own shelter.
Tiger salamanders have a fascinating and adaptable life process. Typically, Tiger Salamander larvae feed and grow during the spring and early summer and metamorphose two to five months after hatching. However, some populations never metamorphose. If the water system where they live is permanent, and should the environment surrounding the ponded area be dry and inhospitable, they may retain crucial larval characteristics, gills and a wide tail fin that allow them to live underwater. These salamanders mature in the water and even are able to mate and reproduce, although they maintain the body of an immature. This process is called neoteny.
Other Tiger Salamanders, in response to the seasonal drying out of their aquatic habitat, must be able to metamorphose on demand. They even may metamorphose if they are removed from water and handled temporarily.
Those Barred Tiger Salamanders that are lucky enough to breed, either as terrrestrial or aquatic salamanders, usually do so in late winter, but breeding may take place whenever there is enough moisture. Once the female has attached her egg masses to underwater debris in temporary pools, she has nothing more to do with them. They hatch three to five weeks later, depending on water temperature. Habitat and Distribution The Barred Tiger Salamander ranges from central Nebraska to northeastern Mexico. They are distributed throughout Texas except for the eastern quarter. They can be found near water in forested and prairie areas where there is adequate moisture. It's difficult not to be impressed with the tiger salamander, Ambystoma tigrinum, when you first see one. Its large size and almost comical appearance make it one of the most recognizable of the salamandrids. Its size often exceeds 30 cm, and its distribution ranges from Canada to the Mexican tropics.
Belonging to the family of mole salamanders, the tiger salamander's key identification points are: a broad flat head with a rounded snout, ridiculously small eyes, and a pair of tubercles on the bottom of the feet. Markings consist of spots, blotches or bars of white to cream to light yellow on a black background. The ventral color may be olive or yellow.
Seven subspecies are recognized to date, five of which occur in the west. Only one, the California tiger salamander, A. t. californiense, is found naturally in California. Recently, herpetologists have begun to suspect that the tiger salamander is a composite of several species, each with much smaller ranges and tolerances.
Little is known of their life in the wild. The subspecies ' distributions are dubious because the larvae ("water dogs") are a popular fishing bait and have spread through accidental or forced introduction into new waterways.
A. tigrinum can be found under rocks, woodpiles or in squirrel holes near streams and ponds. They are often found crossing roads at night during spring rains. Adults can be found "piling up" in a burrow. This behavior is thought to reduce the surface area of individuals exposed to evaporation during dry weather to prevent dehydration.
Mating occurs from November to June. Sexing is difficult, but males have longer tails and hind limbs. They will exhibit a swelling around the base of the cloacae when ready to mate. Courtship begins as the male and female circle each other on the bottom of a pool, nudging each other. The male will rub his chin on the head, neck and back of the female. He may push or otherwise entice the female to follow him to where she will pick up a spermatophore he deposited. The female will lay eggs one to two days later. She may lay them in a loose mass, of a grape-like cluster of up to 125, or individually place them under vegetation.
The larvae may reach maturity within a year in southern regions, or may winter over and metamorphose the following spring. Some may become paedomorphic and reach sexual maturity while still in the larval body form.
Hatchlings of A. tigrinum are one of the most studied aspect of its life. In some populations, especially those without predatory fish, a specialized cannibalistic morph develops (similar to that which occurs in the spadefoot toad of the genus Spea). These cannibals have wider (19%) and longer (13%) heads than their invertebrate eating siblings. The teeth are recurved and up to 30% longer. The effects of this polymorphism can be dramatic. One study reported that 128 A. tigrinum cannibals consumed 1700 conspecifics in a two week period, a 25% reduction in that particular population. This behavior is thought to ensure that some young survive regardless of the food supply.
In the terrarium, A. tigrinum does very well. Its large size makes it easy to feed. Crickets, worms and even strips of meat are readily taken. Temperature is critical, a 20 oC maximum, with 15 oC preferred. Young must be in a large spacious aquarium. The adults must have a damp terrarium with a thick substrate, moss, and ample hiding places of bark and rocks.
Breeding requires a cooling down period and optimum nutrition. In the spring, place the male and female in a shallow aquarium. The males should have swelled cloacae, and the females should be fat with eggs. A. tigrinum eggs are loose and tend to fall apart out of water, so movement of the eggs should be minimized.
Tiger salamanders are easy to acclimate to captivity, are hardy and long lived. It is frustrating to the herpetologist that such a common animal is so enigmatic. This provides the amateur an opportunity to make some significant contributions in the study of this animal.
