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.
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.
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.
The larvae change (through metamorphosis) to terrestrial salamanders in two to three months after hatching.
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)
Once a female deposits her eggs in the water, there is no further parental care.
The lifespan of small-mouthed salamanders is not known. (Lannoo, 2006)
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).
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.
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.
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.
There are no negative impacts of small-mouthed salamanders on humans.
Small-mouth salamanders eat slugs and worms and help keep pest species numbers down. In turn they are food for other animals.
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.
Tanya Dewey (editor), Animal Diversity Web.
Kristi Roy (author), Michigan State University, James Harding (editor), Michigan State University.
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.