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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Three-toed Amphiuma

Taxonomy: available through www.itis.gov

Native Range: The distribution of Amphiuma tridactylum is within the Gulf Coast Plain, centered on the lower Mississippi River from Texas to western Alabama, and north to southern Illinois and extreme southwestern Kentucky (Behler, 1979).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: The Three-toed Amphiuma often is found in bottomland marshes and lakes, bayous, cypress sloughs, and streams in hilly regions, frequently occupying crayfish burrows (Conant, 1975; Behler and King, 1979; Conant and Collins, 1998; Petranka, 1998). It is especially abundant in drainage ditches in suburban and agricultural areas of the lower Mississippi River (Behler and King, 1979).  This amphiuma will move overland during and following heavy rains (Behler and King, 1979; Conant and Collins, 1998). It spends most of the time hiding in heavily vegetated areas of permanent bodies of slow moving water, such as swamps, ponds, and lakes.

The adult Three-toed Amphiuma is capable of burrowing through soft mud and utilizing crayfish burrows. It can remain in these refugia for many months without feeding during droughts. This species often moves on land during nights with heavy rainstorms. They have been observed 12 m from the water’s edge (Petranka, 1998).

Amphiuma tridactylum is a nocturnal carnivore. Crawfish constitute a large proportion of the diet, followed by annelids, insects, mollusks, fishes, small turtles, and sometimes skinks along the shoreline (Chaney 1951; Fontenot and Fontenot, 1989). This species is preyed upon by Mudsnakes (Faracina abacura) and Cottonmouths (Agkistrodon piscivorous) (Behler, 1979; Petranka, 1998).

Mating occurs from December to June, and nesting from April to October. Unlike other amphiumas, this species has internal fertilization (Kreeger, 1942; Cagle, 1948; Petranka, 1998).  The females are capable of storing viable sperm for at least 6–8 months (Kreeger 1942). Clutch size ranges from 44–282 with an average of 201 (Fontenot, 1999). Eggs are deposited in the water near land in coiled strings and are guarded by the female until hatching. The eggs generally are exposed to air as the water recedes. The larval stage lasts a mere 3 weeks. Sexual maturity is reached in 3–4 years (Petranka, 1998).

Means of Introduction: Pet trade. Several dozen per year are sold from Louisiana as pets, whereas several hundred to about 1,000 are sold annually to biological suppliers for laboratory experiments. Most are taken as off-catch during crayfish trapping.

Status: Based on the fact that several were collected, it is assumed that this species is established.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Amphiumas are known to inflict a painful bite and also are known to flee when capture is attempted (Dundee and Rossman, 1989; Petranka, 1998). They also are covered with mucus slime and have thick skin, making them extremely difficult to grasp. There are two native species of amphiuma in Florida, the one-toed (A. pholeter) and the two-toed (A. means). As the common names imply, they can be distinguished by the number of toes on each leg.

References: (click for full references)

Behler, J.L. and F.W. King. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, Inc., New York. 743 pp.

Conant, R. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Houghton Mifflin Company, Boston. 429 pp.

Conant, R. and J.T. Collins. 1998. A Field Guide to Amphibians and Reptiles: Eastern and Central North America. Third edition, expanded. Houghton Mifflin Company, Boston, Massachusetts.

Dundee, H.A. and D.A. Rossman. 1989. The Amphibians and Reptiles of Louisiana. Louisiana State University Press.

Krysko, K.L. and 12 others. 2011. Verified non-indigenous amphibians and reptiles in Florida from 1863 through 2010: Outlining the invasion process and identifying invasion pathways and stages. Zootaxa 3028:1-64.

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

Author: Fuller, P.

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.