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Ambystoma talpoideumMole Salamander

By Ashlee Behr

Geographic Range

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. (Garland, 2002; Lannoo, 2005; Williams and MacGowan, 2004)

Habitat

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. (Garland, 2002; Lannoo, 2005; Rothermel and Luhring, 2005; Williams and MacGowan, 2004)

  • Aquatic Biomes
  • lakes and ponds
  • temporary pools
  • Range elevation
    0 to 700 m
    0.00 to 2296.59 ft

Physical Description

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. (Garland, 2002; Lannoo, 2005; Rothermel and Luhring, 2005; Ryan and Swenson, 2001; Verrell and Krenz, 1998)

  • Sexual Dimorphism
  • male larger
  • Range length
    8 to 12 cm
    3.15 to 4.72 in

Development

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. (Ryan and Swenson, 2001; Whiteman, et al., 2006; Winne and Ryan, 2001)

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. (Patterson, 1978; Ryan and Plague, 2004; Ryan and Semlitsch, 2003; Ryan and Swenson, 2001; Whiteman, et al., 2006; Winne and Ryan, 2001)

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. (Kinkead and Otis, 2007; Lannoo, 2005; Ryan and Plague, 2004; Whiteman, et al., 2006)

Reproduction

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. (Calfee, et al., 2006; Duellman and Trueb, 1994; Lannoo, 2005; Ryan and Plague, 2004)

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. (Kinkead and Otis, 2007; Lannoo, 2005; Ryan and Plague, 2004; Whiteman, et al., 2006)

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. (Kinkead and Otis, 2007; Lannoo, 2005; Ryan and Plague, 2004; Whiteman, et al., 2006)

  • 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

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. (Semlitsch, 1985)

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female

Lifespan/Longevity

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. (Lannoo, 2005)

  • Typical lifespan
    Status: wild
    10 to 20 years

Behavior

Mole salamanders can be active at any time of the day, although most activity is at night. Their activity patterns and seasonal migrations are influenced by environmental conditions, such as rainfall and temperature. Terrestrial salamanders are active and migrate on moist, cool nights. These salamanders are relatively sedentary, occurring either in their natal pond (as aquatic morphs) or in the forests around breeding ponds (as terrestrial morphs). Adults are found farther from breeding ponds than juveniles. On average, adult salamanders travel 170 m to breeding ponds while juveniles travel approximately 50 m. The peak period of emigration of terrestrial juveniles from breeding ponds occurs between June and November, when temperatures are higher and pond drying becomes more of a factor. (Lannoo, 2005; Patterson, 1978; Whiteman, et al., 2006)

  • Range territory size
    3.61 to 5.29 m^2

Home Range

Terrestrial mole salamanders spend the majority of their lives under ground or under leaf litter and other debris. Mole salamanders are found in home ranges of 3.61 to 5.29 square meters. (Lannoo, 2005)

Communication and Perception

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. (Kinkead and Otis, 2007; Lannoo, 2005)

Food Habits

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. (Lannoo, 2005; Whiteman, et al., 2006)

  • Animal Foods
  • amphibians
  • eggs
  • insects
  • terrestrial non-insect arthropods
  • terrestrial worms
  • zooplankton
  • Other Foods
  • microbes

Predation

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. (Boone, et al., 2002; Lannoo, 2005; Whiteman, et al., 2006)

Ecosystem Roles

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. (Calfee, et al., 2006; Lannoo, 2005)

Commensal/Parasitic Species
  • nematodes (Brachycoelium salatnandrae)

Economic Importance for Humans: Positive

Healthy mole salamander populations are indicators of aquatic system health. (Grant, et al., 2005; Lannoo, 2005; Ryan and Semlitsch, 2003)

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. (DuRant and Hopkins, 2008)

  • Positive Impacts
  • research and education
  • controls pest population

Economic Importance for Humans: Negative

There are no known negative effects of Ambystoma talpoideum on humans.

Conservation Status

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. (Chazal and Niewiarowski, 1998; Lannoo, 2005; Moseley, et al., 2004; Rothermel and Luhring, 2005)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Ashlee Behr (author), Radford University, Karen Powers (editor, instructor), Radford University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

visual

uses sight to communicate

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

References

Boone, M., D. Scott, P. Niewiarowski. 2002. Effects of Hatching Time for Larval Ambystomatid Salamanders. Copeia, 2: 511-517.

Calfee, R., C. Bridges, E. Little. 2006. Senstivity of Two Salamander (ambystoma) Species to Ultraviolet Radiation. Journal of Herpetology, 40: 35-42.

Chazal, A., P. Niewiarowski. 1998. Responses of Mole Salamanders to Clearcutting: Using Field Experiments in Forest Management. Ecological Applications, 8: 1133-1143.

DuRant, S., W. Hopkins. 2008. Amphibian Predation on Larval Mosquitoes. Canadian Journal of Zoology, 86/10: 1159-1164.

Duellman, W., L. Trueb. 1994. Biology of Amphibians. Baltimore, Maryland: JHU Press.

Garland, M. 2002. Mole Salamander. Illinois Natural History Survey Reports, 370: 6.

Grant, E., R. Jung, K. Rice. 2005. Stream Salamander Species Richness and Abundance in Relation to Environmental Factors in Shenandoah National Park, Virginia. American Midland Nationalist, 153/2: 348-356.

Griffiths, R., T. Beebee. 1992. Decline and Fall of the Amphibians. New Scientist, 134/1827: 25-29.

Hayslett, M. 2003. Natural History of the Mole Salamander Ambystoma talpoideum in Virginia. Virginia Journal of Science, 38: 304-318.

Kinkead, K., D. Otis. 2007. Estimating Superpopulation Size and Annual Probability of Breeding for Pond-Breeding Salamanders. Herpetologica, 63: 151-162.

Lannoo, M. 2005. Amphibian Declines: The Conservation Statues of United States Species. Berkeley, CA: Berkeley University of California Press.

Mitchell, J. 1997. Life in a Pothole. Virginia Wildlife, 58/4: 5-9.

Moseley, K., S. Castleberry, M. Ford. 2004. Coarse woody debris and pine litter manipulation effects on movement and microhabitat use of Ambystoma talpoideum in a Pinus taeda stand. Forest Ecology and Management, 191: 387-396.

Patterson, K. 1978. Life History Aspects of Paedogenic Populations of the Mole Salamander, Ambystoma talpoideum. Capeia, 1978: 649-655.

Radis, R. 2001. Mole Salamanders. New Jersey Audubon, 27/1: 21-22.

Rothermel, B., T. Luhring. 2005. Burrow Availability and Desiccation Risk of Mole Salamanders (Ambystoma talopoideum) in Harvested versus Unharvested Forest Stands. Journal of Herpetology, 39: 619-626.

Ryan, T., G. Plague. 2004. Hatching asynchrony, survival, and the fitness of alternative adult morphs in Ambystoma talpoideum. Oecologia, 140: 46-51.

Ryan, T., R. Semlitsch. 2003. Growth and the expression of alternative life cycles in the salamander Ambystoma talpoideum (Caudata: Ambystomatidae). Biological Journal of the Linnean Society, 80: 639-646.

Ryan, T., G. Swenson. 2001. Does Sex Influence Postreprroductive Metamorphosis in Ambystoma talpoideum?. Journal of Herpetology, 35: 697-700.

Semlitsch, R. 1985. Reproductive Strategy of a Facultatively Paedomorphic Salamander Ambystoma talpoideum. Oecologia, 65: 305-313.

Verrell, P., J. Krenz. 1998. Competition for mates in the mole salamander, Ambystoma talpoideum : Tactics that may maximize male mating success. Behavior, 135: 121-138.

Whiteman, H., J. Krenz, R. Semlitsch. 2006. Intermorph breeding and the potential for reproductive isolation in polymorphic mole salamanders (Ambystoma talpoideum. Behavioral Ecological Sociobiology, 60: 52-61.

Williams, R., B. MacGowan. 2004. Natural History Data on the Mole Salamander (Ambystoma Talpoideum) in Indiana. Proceedings of the Indiana Academy of Science, 113: 147-150.

Winne, C., T. Ryan. 2001. Aspects of Sex-Specific Differences in the Expression of an Alternative Life Cycle in the Salamander Ambystoma talpoideum. Capeia, 1: 143-149.

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