BioKIDS home

Kids' Inquiry of Diverse Species

Small-mouthed Salamander

Ambystoma texanum

What do they look like?

Small-mouthed salamanders have a small head with a blunt, short snout. The head tends to look swollen behind the eyes and the lower jaw barely goes beyond the upper jaw. The color of the back varies from pale gray to black. There is a pattern of light blotches on their backs, becoming darker on the sides and extending to the dark belly. During the breeding season small-mouthed salamanders may be more pale in color and have more obvious light markings. Adult length is normally between 11 and 17.8 cm (4.3 to 7 inches). Small-mouthed salamanders have 14 to 16 costal grooves (grooves along their sides, which show you where the ribs are). Males are smaller with longer and more compressed tails. Larvae usually have light bars or crossbands on an olive green or dark brown background.

  • Sexual Dimorphism
  • sexes shaped differently
  • Range length
    11 to 17.8 cm
    4.33 to 7.01 in

Where do they live?

Small-mouthed salamanders are found from northeastern Ohio west into Missouri and eastern Nebraska. The northern edge of the range is southeast Michigan and the southern range goes through western Kentucky and Tennessee to the Gulf of Mexico. They are even found on several islands in southern Lake Erie.

What kind of habitat do they need?

Small-mouthed salamanders are usually found in lowland forests. They can also live in more open habitats, like prairies, as long as there are breeding ponds without fish. Small-mouthed salamanders can breed in a bigger variety of breeding habitats than can many other salamander species. They can breed in temporary forest ponds, runoff ponds, flooded areas, river backwaters, and roadside ditches. They do not travel far from their breeding ponds, so good habitat near the pond is important.

How do they grow?

The larvae change (through metamorphosis) to terrestrial salamanders in two to three months after hatching.

How do they reproduce?

Males bump and nudge females and each other, they will then move away from the group and deposit small packages of sperm on the pond-bottom or on a stick or leaf. Females then come along and collect the sperm package.

Small-mouthed salamanders breed very early in the year. Migration to breeding ponds seems to be triggered by just a few days of rain in late winter, often even while ice still covers portions of breeding ponds. They tend to stay closer to breeding ponds in summer and late winter than other salamander species. A single female can produce 300 to 700 eggs each year, which are placed in small, loose gelatinous masses of 3 to 30 eggs. The eggs hatch in 3 to 8 weeks; young mature to breeding size in their second year. (Harding, 1997; Petranka, 1984)

  • How often does reproduction occur?
    Small-mouthed salamanders breed once each year.
  • Breeding season
    Small-mouthed salamders breed in early spring.
  • Range number of offspring
    300 to 700
  • Range time to hatching
    3 to 8 weeks
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Average age at sexual or reproductive maturity (male)
    2 years

Once a female deposits her eggs in the water, there is no further parental care.

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

How long do they live?

The lifespan of small-mouthed salamanders is not known. (Lannoo, 2006)

How do they behave?

Members of the family Ambystomatidae are commonly called the mole salamanders because of their secretive underground lifestyle (Indiviglio 1997). When not breeding, A. texanum individuals tend to be hidden under rotting logs, rocks or leaf litter. They also make use of burrows dug by other animals including crayfish and small mammal burrows. An evening rain occasionally provokes them to emerge above ground (Harding 1997).

What do they eat?

Adult small-mouth salamanders eat insects, spiders, slugs, worms, and aquatic crustaceans. Larva eat mostly small, aquatic invertebrates like Daphnia and young pillbugs. They even eat larvae of their own or other species of salamanders.

  • Animal Foods
  • amphibians
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms
  • aquatic crustaceans

What eats them and how do they avoid being eaten?

Small-mouthed salamanders have glands on the top of their tails that secrete a substance that either tastes bad or is poisonous. When they are threatened by a predator, small-mouthed salamanders raise and curl their tail in the predator's direction. They also hide their head under the tail. This behavior is most often used when attacked by a snake. Larvae are preyed on by dragonfly larvae and tiger salamander larvae.

What roles do they have in the ecosystem?

Small-mouthed salamanders are predators of small invertebrates and are preyed on by small to medium-sized predators, such as snakes, birds, and other salamanders. They are important members of healthy woodland and grassland communities.

Do they cause problems?

There are no negative impacts of small-mouthed salamanders on humans.

How do they interact with us?

Small-mouth salamanders eat slugs and worms and help keep pest species numbers down. In turn they are food for other animals.

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

Small-mouthed salamanders are common through much of their range. They are tolerant of many different kinds of habitats. On the edges of their range, where numbers are low, management for this species would be beneficial, such as in Michigan, where small-mouthed salamanders are listed as endangered. To protec small-mouthed salamanders, areas with known populations should be protected and breeding ponds should be protected from invasion by fish species, which eat the eggs and larval salamanders.

Some more information...

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Kristi Roy (author), Michigan State University, James Harding (editor), Michigan State 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

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.

carnivore

an animal that mainly eats meat

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.

heterothermic

animals that have little or no ability to regulate their body temperature, body temperatures fluctuate with the temperature of their environment, often referred to as 'cold-blooded'.

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.

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

native range

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

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.

seasonal breeding

breeding is confined to a particular season

sexual

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

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.

tropical savanna and grassland
savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

References

Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region. Ann Arbor, MI: University of Michigan Press.

Lannoo, M. 2006. "Ambystoma texanum" (On-line). Amphibiaweb. Accessed November 02, 2006 at http://www.amphibiaweb.org/cgi-bin/amphib_query?query_src=aw_search_index&table=amphib&special=one_record&where-genus=Ambystoma&where-species=texanum.

Maurer, E., A. Sih. 1996. Ephemeral Habits and Variation in Behavior and Life History: Comparisons of Sibling Salamander Species. Oikos, 76: 337-349.

McWilliams, S., M. Bachmann. 1989. Predatory Behavior of Larval Small-Mouthed Salamanders. Herpetologica, 45(4): 459-467.

Petranka, J. 1984. Breeding Migrations, Breeding Season, Clutch Size, and Oviposition of Stream-Breeding Ambystoma texanum. Journal of Herpetology, 18(2): 106-112.

 
University of Michigan Museum of ZoologyNational Science Foundation

BioKIDS home  |  Questions?  |  Animal Diversity Web  |  Cybertracker Tools

Roy, K. 2000. "Ambystoma texanum" (On-line), Animal Diversity Web. Accessed April 17, 2014 at http://www.biokids.umich.edu/accounts/Ambystoma_texanum/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
Copyright © 2002-2014, The Regents of the University of Michigan. All rights reserved.

University of Michigan