The life cycle of a mole salamander has a great impact on the individual's longevity. Once a salamander becomes mature in an aquatic environment, 45% of adults will die before ever leaving the breeding pond. This high rate of mortality is due to pond drying and aquatic predators. When a salamander becomes terrestrial, however, chances of survival improve greatly. Mole salamanders in the wild can live up to 20 years.
Typical lifespan
Status: wild: 10 to 20 years.
Mole salamanders are subject to predation from other salamanders as well as other aquatic predators. Larval salamander communities are highly structured by predation. Mole salamanders tend to breed later than other species of Ambystoma and are subject to more competition and predation as a result. Marbled salamanders (Ambystoma opacuum) breed earlier and their larvae feed on mole salamander eggs and larvae. Bluegill sunfish, if present, also feed heavily on mole salamander eggs. When a terrestrial adult mole salamander is attacked, is will stand in a posture with its head lowered in order to expose the well developed paratoid glands to the predator. These glands secrete a noxious chemical. They also lash their tails, head-butt, bite, writhe, flee, or feign death to deter predators.
Known Predators:
Mole salamanders are facultatively paedomorphic; they can either become terrestrial adults (metamorphic adults) or retain their aquatic larval form even as they become sexually mature (paedomorphic, branchiate, or neotenic adults). Paedomorphic adults can eventually undergo metamorphosis or they may remain in the aquatic form throughout life. Terrestrial adults live in areas surrounding breeding ponds while paedomorphic adults remain in permanent ponds. Environmental conditions present during larval development can determine which life form an individual salamander will become. Both mole salamander morphs have short, stout bodies with broad, disproportionally large heads. Body size of terrestrial and aquatic males varies across populations and time. In some years and ponds, aquatic males will be larger, on average, than terrestrial males. In other years, the opposite can be true. Body size also varies within the same year, because smaller terrestrial adults have been known to arrive at a pond before larger adults. Neotenic adults have distinctive yellow ventral stripes that makes identification of this species more accurate. They also have light and dark stripes on their their bellies, that is present even in the larval form. Terrestrial adults can have variable body color, ranging from gray to black sometimes with clusters of small bluish-white flecks that are concentrated on the tail and back. Another distinguishing feature of the mole salamander is that there is often a white edge running along the top of the tail. For a period of time after the metamorphosis to a terrestrial creature, these salamanders will still display the remnants of the yellow ventral stripes that are so prominent in the neotonic life cycle.
Range length: 8 to 12 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; polymorphic
Sexual Dimorphism: male larger
Mole salamanders use their sense of sight and smell the most to communicate with conspecifics and to perceive their environment. Tactile cues may also be important.
Communication Channels: visual ; tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
There are two mole salamander morphs, each occupying different habitats. Terrestrial mole salamanders are most abundant in expansive floodplain forests near ponds or similiar bodies of water. They can be found in areas surrounding gum and cypress ponds. Those salamanders living outside the Atlantic and Gulf coasts can be found in forested uplands. Terrestrial salamanders often live in burrows in moist soil and leaf litter. Seasonal and/or semipermanent ponds are associated with producing terrestrial adults. Neotenic, or aquatic, mole salamanders thrive in fishless, permanent ponds. Eggs are laid by both terrestrial and neotenic adults on twigs or other debris under the water.
Range elevation: 0 to 700 m.
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: forest
Aquatic Biomes: lakes and ponds; temporary pools
Wetlands: swamp
Other Habitat Features: riparian
Ambystoma talpoideum is endemic to the southeastern and central United States. It is found along the southern Atlantic and Gulf Coastal plains, north along the Mississippi River to southern Illinois, and from central South Carolina to eastern Texas. There are isolated populations in Virginia, Tennessee, Kentucky, North Carolina, and northern South Carolina, Georgia, and Alabama. Mole salamanders are not present in southern Florida or southern Louisiana.
Biogeographic Regions: nearctic (Native )
Mole salamanders are carnivorous. Recently hatched larvae feed on zooplankton and other small, aquatic organisms. As larvae develop, they add larger prey items as they are able to ingest them. Mole salamanders pick their prey based on size relative to their own body size, and tend to choose larger prey as they grow. Larvae have been known to eat mole salamander eggs as well as eggs of other Ambystoma salamanders. They also eat copepods, ostracods, water fleas, and midge larvae. Adult mole salamanders have been described as opportunistic feeders and eat a variety of items, including aquatic insects, tadpoles, earthworms, athropods, and an assortment of other invertebrates.
Animal Foods: amphibians; eggs; insects; terrestrial non-insect arthropods; terrestrial worms; zooplankton
Other Foods: microbes
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods)
The health of salamander populations is used as an indicator of ecosystem health because of their sensitivity to toxins and increased ultraviolet radiation. Declining mole salamander populations are used as an indicator of water quality. Juvenile mole salamanders serve as prey to larger terrestrial and aquatic predators. Mole salamanders also act as predators, consuming both aquatic and terrestrial invertebrates.
Commensal/Parasitic Species:
Healthy mole salamander populations are indicators of aquatic system health.
Larval mole salamanders successfully reduce mosquito larvae abundance. Mosquito consumption is directly related to salamander body size. In one study, researchers found that the largest salamanders (4.4 g) consumed 902 mosquitoes in one day.
Positive Impacts: research and education; controls pest population
There are no known negative effects of Ambystoma talpoideum on humans.
Mole salamander life cycles are characterized by facultative paedomorphosis. There are two different life cycles that these salamanders can follow. One life cycle occurs when aquatic larvae undergo metamorphosis and become terrestrial juveniles that will mature in terrain surrounding the breeding area. These individuals are referred to as terrestrial or metamorphic adults. The alternate life cycle is when aquatic larvae retain their aquatic morphology as they mature and remain in their natal ponds. These are referred to as branchiate, neotenic, or paedomorphic adults.
Factors that influence the metamorphosis of mole salamanders at different stages in their lives include sex, altitude, temperature, nutrition, and pond drying. Size and metabolic rates differ between the sexes, which can lead to differences in metamorphosis. As a general standard, metamorphosis can occur once a salamander has reached a minimum of 25mm snout-vent length. Males typically reach this size sooner after hatching and can undergo metamorphosis earlier. Regardless of sex, most salamanders will undergo metamorphosis between 12 and 15 months after hatching. Metamorphosis after 15 months is typically associated with high altitudes and cooler temperatures. After metamorphosis, terrestrial juveniles remain immature and require several months to mature. Nutritional resources also play into timing of metamorphosis. Salamanders are more likely to metamorphosize when food levels and growth rates are higher later in development. The availability of food during the larval period is also directly related to metamorphosis. Environmental influences play a huge role in life cycles. When salamanders are hatched in a permanent pond, they typically remain there for at least a year or could even remain permanently aquatic. Sexually immature salamanders can metamorphosize early if they are exposed to certain conditions, such as pond drying. If a salamander remains aquatic, they remain immature and go through a period known as overwintering, then they can either metamophosize or become a branchiate adult. Aquatic forms of mole salamanders tend to mature at age a younger age and can also breed earlier. It is still possible for branchiate adults to undergo metamorphosis even after reaching sexual maturity.
Larval growth is related to egg and hatchling size. The smaller the egg, the smaller the larva will be at hatching. Time to hatching also influences length of the larval period, survival to metamorphosis, and size at metamorphosis. Eggs can hatch anywhere between 20 to 60 days after being laid and larval transformation occurs 60 to 90 days after hatching.
Development - Life Cycle: neotenic/paedomorphic; metamorphosis
In North Carolina, mole salamanders are listed as a species of special concern and a permit is required to conduct any activity involving this species. A similar permit is also required in Tennessee, where the species is considered in need of management. Mole salamander populations have been affected by clear cutting of forests surrounding breeding ponds, draining or filling of breeding ponds, and the introduction of predatory fishes due to the deepening of breeding ponds. However, mole salamander populations are currently considered stable throughout most of their range.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Mole salamanders exhibit complex courtship behavior and use visual, chemosensory, and tactile cues during courtship. Aquatic adults attract females through tail-waving. Aquatic individuals peak breeding occurs earlier than terrestrial individuals, in early November as compared to mid-January. This difference in breeding times can lead to partial reproductive isolation. Courtship in heteromorphic pairing tends to occur less frequently, proceeds more slowly, and is more likely to end before sperm transfer. Also, female mate choice may influence mating success among morphs. Females, regardless of morph, have a strong aversion to aquatic males.
Mating System: polygynandrous (promiscuous)
Breeding in mole salamanders occurs mainly from December to March. There is some variation in the time of breeding due to climatic conditions that can restrict the movement of some individuals. Mole salamanders may skip breeding in a year if conditions are not appropriate. On average, only about 35% of mole salamanders will breed in any given year. Ponds used for breeding tend to be ponds with no fish in forested areas. Ponds can be permanent, semi-permanent, or seasonal. Mole salamanders can also breed in areas such as gravel pits or roadside ditches that have been filled with water during heavy rains. Terrestrial and aquatic morphs successfully interbreed, with intermorph breeding influenced by temporal, spatial, and behavioral separation. Breeding cycles vary between aquatic and terrestrial adults, resulting in temporal separation of breeding. Terrestrial adults tend to breed after pond filling and are more susceptible to competitive and predatory pressures. Terrestrial adults migrate to breeding ponds mainly at night and during periods of heavy, sustained rains and cold temperatures. If these conditions aren't met, then fewer terrestrial adults will come to breeding ponds. Aquatic adults remain in their original breeding ponds to reproduce and tend to breed earlier than terrestrial adults. In some cases, the offspring of aquatic adults may hatch before terrestrial adults even begin to breed. Spatial separation of the morphs within breeding ponds depends on the depth at which concentrations of aquatic individuals is greatest.
Mole salamanders reproduce sexually. Male salamanders produce balls of sperm and other substances, called spermatophores. Males can produce multiple spermatophores and can compete with other males by covering competing spermatophores with their own. Females will collect a spermatophore in their cloacae to fertilize the eggs. When the female's eggs become fertilized, she will lay them in a group, called a clutch, loosely attached to submerged vegetation, such as a twig or other object, in the pond. Clutch size is positively correlated with body size in the female salamander. Larger terrestrial females produce larger clutches than same-age aquatic females. On average, a female will lay between 200 to 700 eggs per year. Eggs are 1 to 3 mm in diameter. Females lay their eggs at night and can take several days to lay all of her eggs. Populations that reside in the Atlantic coastal plain tend to have larger clutch sizes. Both male and female mole salamanders reach sexual maturity around 2 years of age or when they are larger than 44 mm.
Breeding interval: Mole salamanders breed once a year.
Breeding season: Breeding season typically occurs between December and March and lasts between 7 and 15 days.
Range number of offspring: 200 to 700.
Range time to hatching: 20 to 60 days.
Range time to independence: 12 to 14 months.
Average time to independence: 15 months.
Average age at sexual or reproductive maturity (female): 2 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Male salamanders have no parental investment in their young. Female mole salamanders provision their eggs with yolk for development and place them in a protected area in a breeding pond. After egg deposition, there is no further parental involvement.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female)
Ambystoma talpoideum, the mole salamander, is a species of salamander found in much of the eastern and central United States, from Florida to Texas, north to Illinois, east to Kentucky, with isolated populations in Virginia and Indiana. Older sources often refer to this species as the tadpole salamander because some individuals remain in a neotenic state. This salamander lives among the leaf litter on the forest floor, migrating to ponds to breed.
Mole salamanders are stocky, with short bodies and large heads. They can grow to 10 cm (4 in) in length. They are normally gray or dark brown in color, with darker mottling and lighter gray undersides. Males can be distinguished by the presence of a swollen cloaca. Larvae and paedomorphic adults are aquatic and have large feathery gills. A. talpoideum can be distinguished from other salamander larvae by the presence of two light stripes on their underside[2]
Mole salamanders are found in south eastern lowland areas of the Gulf Coastal Plains of the United States. Their main range extends from eastern Texas to southern South Carolina and inland as far as southern Illinois. It is absent from southern Florida and Louisiana, and there are separate populations in Kentucky, Virginia, Tennessee, North Carolina, northern South Carolina, northern Georgia and northern Alabama. There is also a small isolated population within the southernmost tip of Indiana.[3] They inhabit floodplain pine or broadleaf forests, especially near gum and cypress ponds. Adults live under the surface of leaf litter while larvae are aquatic and found in ponds and ephemeral, fish-free waters.[4]
Primarily nocturnal, the mole salamander is found in habitats of moist forest debris, usually near a permanent source of water. The adult range is up to about 5 square metres (54 sq ft) and the animals migrate to near bodies of water on rainy nights in winter when the breeding season approaches. The eggs are laid in the spring, during heavy rains. Some larvae undergo metamorphosis while others are neotenic and retain their gills. In larger bodies of water where predatory fish like the bluegill (Lepomis macrochirus) are present, metamorphosis is more common. When ponds were dried it also showed higher rates of metamorphosis.[5] When attacked, adults and juveniles lower their heads to expose their parotoid glands which exude a noxious secretion.[4] This salamander is an opportunistic feeder, eating almost anything smaller than itself which it can overpower, including various arthropods and tadpoles.[4] It has been revealed that A. talpoideum's diet consists almost completely of various arthropods and only a small number of other Ambystomatidae larvae.[6]
In its Red List of Threatened Species, the IUCN lists Ambystoma talpoideum as being "Least Concern" because the population trend is stable. Threats to this species include destruction of forest ponds and swamp habitat, the filling in or deepening of breeding ponds, and the introduction of predatory fish.[1] In Indiana, the mole salamander is listed as an endangered species.[7]
Data related to Ambystoma talpoideum at Wikispecies
Ambystoma talpoideum, the mole salamander, is a species of salamander found in much of the eastern and central United States, from Florida to Texas, north to Illinois, east to Kentucky, with isolated populations in Virginia and Indiana. Older sources often refer to this species as the tadpole salamander because some individuals remain in a neotenic state. This salamander lives among the leaf litter on the forest floor, migrating to ponds to breed.