| Tiger salamander | |
|---|---|
 | |
| Several in captivity | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Urodela |
| Family: | Ambystomatidae |
| Genus: | Ambystoma |
| Species: | A. tigrinum |
| Binomial name | |
| Ambystoma tigrinum (Green, 1825) | |
| Synonyms [2] | |
| |
The tiger salamander (Ambystoma tigrinum) is a species of mole salamander [2] and one of the largest terrestrial salamanders in North America. [3]
These salamanders usually grow to a length of 6–8 in (15–20 cm) with a lifespan of around 12–15 years. [4] They are characterized by having markings varying in color on the back of their head, body, and tail. [5] The coloring of these spots range from brownish yellow to greenish yellow, while the rest of their back is black or dark brown. [3] They have short snouts, thick necks, strong legs, and lengthy tails. [6] Tiger salamanders are a sexually dimorphic species, as the males are larger in body size, as well as have longer and higher tails than females. [7] Their diet consists largely of small insects, snails, slugs, frogs, and worms, although it is not rare for an adult to turn cannibalistic and consume its own kind. [5] [8] Cannibalism in these salamanders can almost always be traced back to a large volume of competing predators and lack of prey in the area. [9] If the opportunity presents itself, tiger salamanders will even feed on other smaller salamander species, lizards, snakelets (baby snakes), and newborn mice. [8] [10]
Tiger salamanders habitats range from woodlands crowded with conifer and deciduous trees to grassy open fields. [3] These amphibians are secretive creatures who spend most of their lives underground in burrows, making them difficult to spot. [4] One significant requirement these salamanders need to thrive is loose soil for burrowing. [11] Tiger salamanders are almost entirely terrestrial as adults, and usually only return to the water to breed. The ideal breeding condition for tiger salamanders ranges from wetlands, such as cattle ponds and vernal pools, to flooded swamps. [5] The colonization of wetlands by tiger salamanders has been positively related to the area of the wetlands. [12] This species is most commonly found on the Atlantic coast from New York down to Florida. [13] They are known, however, to be the widest ranging species of salamander in North America and have been found in smaller populations from coast to coast. [6] Ambystoma tigrinum populations occurring in northern and eastern regions of the United States are thought to be native populations as evidence from a study uncovered the species in these regions seem to be from relict populations. The species which occur on the west coast of the United States are not necessarily native occurring to the region and occur as a result of introduction for sport fishing bait, which has resulted in hybridization. [14] Though tiger salamanders are not indicators of an ecosystem, they are good indicators of a healthy environment because they need good moist soil to burrow in. But pond disturbance, invasive fish, and road construction threaten the annual population. [15]
Like all ambystomatids, they are extremely loyal to their birthplaces, and will travel long distances to reach them. Some research has shown that females will travel farther than males. [16] However, a single tiger salamander has only a 50% chance of breeding more than once in its lifetime. In a study conducted in South Carolina, breeding migrations of adult tiger salamanders began in late October or November for males and November through February for females. [17] The tiger salamander's ideal breeding period is somewhere between the late winter and early spring, once the ground is warm enough and the water is thawed. [11] Males nudge a willing female to initiate mating, and then deposit a spermatophore on the lake bottom. Some males known as sneaker males will mimic female behavior in order to trick females in taking their spermatophore without alerting the male rival. [18] There appears to be no relation between size and mating success. [19] However, females prefer mates with longer tails over mates with shorter tails. [7] About 48 hours after insemination, the female is ready to deposit her eggs in the breeding pool. [11] One female can lay up to 25–30 eggs per egg mass. She carefully attaches the eggs to secure twigs, grass, and leaves at the bottom of the pool to ensure her eggs safety. [20] In about 12–15 days time, the eggs will be fully hatched and ready to mature in the pool. [20] It takes a tiger salamander approximately three months to reach full maturity and leave the breeding pool. [20] Large-scale captive breeding of tiger salamanders has not been accomplished, for unknown reasons.
The larva is entirely aquatic, and is characterized by large external gills [21] [22] and a prominent caudal fin that originates just behind the head, similar to the Mexican axolotl. 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', [23] and are used extensively in the fishing bait and pet trades. Some populations may not metamorphose at all, and become sexually mature while in their larval form. These are called neotenes, and are particularly common where terrestrial conditions are poor.
Although immune themselves, tiger salamanders transmit the fungus Batrachochytrium dendrobatidis , which is a major worldwide threat to most frog species by causing the disease chytridiomycosis. [24] 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. One of these ranaviruses is even named the Ambystoma tigrinum virus (ATV). This ranavirus only transmits to other salamanders and was not found in fish or other amphibians. [25] Severe mortality of tiger salamander larvae sometimes occurs from recurring ranavirus infections.
The California tiger salamander (Ambystoma californiense) [26] (listed at Vulnerable), the barred tiger salamander (A. mavortium), and the plateau tiger salamander (A. velasci) were all once considered subspecies of A. tigrinum, but are now considered separate species. Genetic studies made it necessary to break up the original A. tigrinum population, though some hybridization between groups occurs.
The California tiger salamander is now federally listed as an endangered species mostly due to habitat loss; however, very few studies have been performed on this species. [27]
The axolotl is also a relative of the tiger salamander. [28] [29] Axolotls live in a paedomorphic state, retaining most characteristics of their larval stage for their entire lifespans. While they never metamorphose under natural conditions, metamorphosis can be induced in them, resulting in a form very similar to the plateau tiger salamander. This is not, however, their natural condition, and dramatically shortens their lifespan. Recently, introgressed tiger salamander (A. tigrinum) DNA was detected in the laboratory axolotl population. [30]
On February 2, 2005, Representative Bob Biggins introduced a bill to make the tiger salamander the official state amphibian of Illinois and to make the painted turtle the official state reptile. The bill was signed into law by Governor Rod Blagojevich on July 19, 2005. [31]
Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense it is a paraphyletic group encompassing all tetrapods, excluding the amniotes. All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura (frogs), Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater, wetland or terrestrial ecosystems. Their life cycle typically starts out as aquatic larvae with gills known as tadpoles, but some species have developed behavioural adaptations to bypass this.
Neoteny, also called juvenilization, is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared to other primates. In progenesis or paedogenesis, sexual development is accelerated.
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten extant salamander families are grouped together under the order Urodela from the group Caudata. Salamander diversity is highest in eastern North America, especially in the Appalachian Mountains; most species are found in the Holarctic realm, with some species present in the Neotropical realm.
The axolotl is a paedomorphic salamander closely related to the tiger salamander. It is unusual among amphibians in that it reaches adulthood without undergoing metamorphosis. Instead of taking to the land, adults remain aquatic and gilled. The species was originally found in several lakes underlying what is now Mexico City, such as Lake Xochimilco and Lake Chalco. These lakes were drained by Spanish settlers after the conquest of the Aztec Empire, leading to the destruction of much of the axolotl's natural habitat.
The mole salamanders are a group of advanced salamanders endemic to North America. The group has become famous due to the presence of the axolotl, widely used in research due to its paedomorphosis, and the tiger salamander which is the official amphibian of many US states, and often sold as a pet.
The spotted salamander or yellow-spotted salamander is a mole salamander common in eastern United States and Canada. It is the state amphibian of Ohio and South Carolina. The species ranges from Nova Scotia, to Lake Superior, to southern Georgia and Texas. Its embryos have been found to have symbiotic algae living in and around them, the only known example of vertebrate cells hosting an endosymbiont microbe.
The California tiger salamander is a vulnerable amphibian native to California. It is a mole salamander. Previously considered to be a subspecies of the tiger salamander, the California tiger salamander was recently designated a separate species again. The California tiger salamander distinct population segment (DPS) in Sonoma County and the Santa Barbara County DPS are listed as federally endangered, while the Central California DPS is listed as federally threatened. The Sonoma County, south San Joaquin, and the Santa Barbara County DPS have diverged from the rest of the California tiger salamander populations for over one million years, since the Pleistocene and they may warrant status as separate species.
Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland usually devoid of fish, and thus allow the safe development of natal amphibian and insect species unable to withstand competition or predation by fish. Certain tropical fish lineages have however adapted to this habitat specifically.
The Jefferson salamander is a mole salamander native to the northeastern United States, southern and central Ontario, and southwestern Quebec. It was named after Jefferson College in Pennsylvania.
The blue-spotted salamander is a mole salamander native to the Great Lakes states and northeastern United States, and parts of Ontario and Quebec in Canada. Their range is known to extend to James Bay to the north, and southeastern Manitoba to the west.
The ringed salamander is a species of mole salamander native to hardwood and mixed hardwood-pine forested areas in and around the Ozark Plateau and Ouachita Mountains of Arkansas, Oklahoma, and Missouri. This species of salamander has slander body, small head, and long tail. They are usually found to have various dorsal color from dark gray to dark brown. Various close relatives are found such as marbled salamander and spotted salamander. This species of salamander has cannibal behavior especially those in large body size.
The streamside salamander is a species of mole salamander from North America, occurring in several Midwestern states of the US.
The long-toed salamander is a mole salamander in the family Ambystomatidae. This species, typically 4.1–8.9 cm (1.6–3.5 in) long when mature, is characterized by its mottled black, brown, and yellow pigmentation, and its long outer fourth toe on the hind limbs. Analysis of fossil records, genetics, and biogeography suggest A. macrodactylum and A. laterale are descended from a common ancestor that gained access to the western Cordillera with the loss of the mid-continental seaway toward the Paleocene.
The California newt or orange-bellied newt, is a species of newt endemic to California, in the Western United States. Its adult length can range from 5 to 8 in. Its skin produces the potent toxin tetrodotoxin.
The Lake Patzcuaro salamander, locally known as achoque, is a paedomorphic species of salamander found exclusively in Lake Pátzcuaro, a high-altitude lake in the Mexican state of Michoacán. First described in 1870 by Alfredo Dugès, the species is named in honor of the French herpetologist Auguste Duméril. However, the salamander has been used as a food source and an ingredient in traditional medicines by the Purépecha people since the Pre-Columbian era. Ambystoma dumerilii are neotenic, meaning they retain their larval characteristics throughout their entire life. This results in adults that have long, heavily filamented external gills, gill slits lined with tooth-like gill rakers, and caudal fins. When stressed, Ambystoma dumerilii can undergo an incomplete metamorphosis, though this is process significantly decreases their lifespan and is often fatal.
The Santa Cruz long-toed salamander is an endangered subspecies of the long-toed salamander, which is found only close to a few isolated ponds in Santa Cruz and Monterey Counties in California. It has a black body, broken yellow or orange irregular striping along its spine, and a tail fin well evolved for swimming. Like other mole salamanders, it is found near pools or slow-moving streams and has a very secretive lifestyle, making it difficult to find.
The marbled salamander is a species of mole salamander found in the eastern United States.
The small-mouth salamander is a species of mole salamander found in the central United States, from the Great Lakes region in Michigan to Nebraska, south to Texas, and east to Tennessee, with a population in Canada, in Pelee, Ontario. It is sometimes referred to as the Texas salamander, porphyry salamander, or the narrow-mouthed salamander. The Kelley's Island salamander was synonymized with A. texanum in 1995.
The barred tiger salamander or western tiger salamander is a species of mole salamander that lives in lower western Canada, the western United States and northern Mexico.
Parthenogenesis is a form of reproduction where eggs develop without fertilization, resulting in unisexual species. This phenomenon is closely related with reproductive modes such as hybridogenesis, where fertilization occurs, but the paternal DNA is not passed on. Among amphibians, it is seen in numerous frog and salamander species, but has not been recorded in caecilians.
