Description
A large, eel-like aquatic salamander. All four limbs are present, but extremely tiny, and there are only two toes on each. As in other species of Amphiuma (Family Amphiumidae), there is a single gill slit, no external gills, and the eyes are lidless (Petranka 1998).

Adult two-toed amphiumas range in size from 46 - 116 cm total length. There are 57 - 60 costal grooves (average 58). The laterally compressed tail is 20-25% of the total body length. The dorsum is black to dark brown or grey and the venter is only slightly lighter (Salthe 1973; Petranka 1998). A dark patch on the chin is difficult to see against the ground coloration (Salthe 1973).

The three species of Amphiuma are similar but can be differentiated based on the number of toes (one, two, or three), coloration, and body size.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Virginia

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (25 records).

Two-toed amphiumas are found in Coastal Plain habitats from southeastern Virgina to eastern Louisiana, near New Orleans. Juveniles and adults live in or near swamps, cypress bays, ditches, sloughs, temporary pools, and sluggish streams (Salthe 1973; Petranka 1998).

This species is almost completely aquatic, but individuals occasionally move overland on rainy nights (Conant and Collins 1991).

Life History, Abundance, Activity, and Special Behaviors
Courtship has not been documented. Breeding apparently occurs during winter months. Fertilization is internal. Females deposit eggs under large cover objects like rocks and logs or in underground burrows. The female coils around the egg mass and attends the eggs until hatching, usually 5 to 6 months after oviposition. Average clutch size is about 200, range 106 - 354 (Salthe 1973; Petranka 1998).

Adults consume vertebrate and invertebrate prey, including salamanders, small frogs, crayfish, as well as a range of smaller invertebrates. Amphiumas have a powerful bite. Foraging activities occur at night and during the day animals retreat to underground burrows, sometimes over a meter deep. Important predators of amphiumas are aquatic snakes like mud and rainbow snakes (Farancia), water snakes (Nerodia), cottonmouths (Agkistrodon), and large wading birds. Defensive behavior of amphiumas is primarily bites from their strong jaws. People should take care when handling these animals. See Petranka (1998) and references therein.

Two-toed amphiumas often function as top predators in their freshwater systems. Their importance in influencing species diversity and community structure is not known. This would be a productive area of investigation, particularly because the wetland habitats where they occur are threatened with continuing loss (Petranka 1998).

Larva
Hatchlings are about 55 mm total length and all four limb are functional at the time of hatching. Gills are resorbed almost immediately after hatching. Juveniles are similar in color to adults. See Petranka (1998) and references therein.

Trends and Threats
The continuing loss of wetland habitats is a threat to populations of amphiumas, and undoubtedly many populations have already been eliminated. Long term studies on amphiuma population trends have not been conducted (Petranka 1998).

Comments
Amphiuma means and A. tridactylum are genetically similar, while A. pholeter is quite distinct and represents an ancient evolutionary offshoot (Karlin and Means 1994). Some authors have argued that A. means and A. tridactylum should be treated as conspecifics. These species, which are sympatric over much of their ranges, differ in coloration, number of toes, and some body proportions. See Salthe (1973) for discussion of this issue.

References

Conant, R. and Collins, J. T. (1991). A Field Guide to Reptiles and Amphibians: Eastern/Central North America. Houghton Mifflin, Boston.

Karlin, A. A., and Means, D. B. (1994). ''Genetic variation in the aquatic salamander genus Amphiuma.'' American Midland Naturalist, 132, 1-9.

Petranka, J. W. (1998). Salamanders of the United States and Canada. Smithsonian Institution Press, Washington D.C. and London.

Salthe, S. N. (1973). ''Amphiuma means Garden. Two-toed Congo Eel.'' Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, 148.1-148.2.

Salthe, S. N. (1973). ''Amphiuma tridactylum Cuvier. Three-toed Congo Eel.'' Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, 149.1-149.3.

Species Account Citation: AmphibiaWeb 2022 Amphiuma means: Two-toed Amphiuma <https://amphibiaweb.org/species/3853> University of California, Berkeley, CA, USA. Accessed Nov 24, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Nov 2024.

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