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.

Macrochelys temminckii
Macrochelys temminckii
(Alligator Snapping Turtle)
Native Transplant

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Macrochelys temminckii (Troost in Harlan, 1835)

Common name: Alligator Snapping Turtle

Synonyms and Other Names: Macroclemys temminckii

The taxonomy of M. temmincki has been reviewed by King and Burke (1989), Pritchard (1989), Lovich (1993), and Iverson et al. (2000).  Although Pritchard (1989) has argued in favor of using the name Macroclemys temmincki, Iverson et al. (2000) follow the more current research of Webb (1995) and use the name Macrochelys temminckii based upon priority.

Taxonomy: available through www.itis.govITIS logo

Identification: The Alligator Snapping Turtle is characterized by a very large head and three rows of spiked scutes (enlarged scales or laminae). The rows of spiked scutes usually form three distinct complete or incomplete keeled ridges on the brown carapace (upper shell), which distinguish M. temminckii from the Snapping Turtle (Chelydra serpentina) (Behler and King, 1979; Pritchard, 1989; Conant and Collins, 1998).   Some of the marginal scutes on the carapace occur in a double row rather than the single row seen in Chelydra (Powell et al., 1998). A strongly hooked beak is present on most, but not all specimens (Pritchard, 1989; Ernst et al., 1994; Conant and Collins, 1998).   The tongue has a unique worm-like appendage ("fishing lure") (Obst, 1986; Ernst and Barbour, 1989; Conant and Collins, 1998; Zug et al., 2001). The plastron (lower shell) is relatively small (Pritchard, 1989; Conant and Collins, 1998). Macrochelys temminckii is the largest freshwater turtle in the U.S. reaching a record carapace length of 800 mm (31.5 in), and weight of 113.9 kg (251 lbs) (Pritchard, 1989; Conant and Collins, 1998). The Alligator Snapping Turtle has been illustrated by numerous authorities (Pope, 1939; Carr, 1952; Ernst and Barbour, 1972, 1989; Mount, 1975; Behler and King, 1979; Pritchard, 1979,1989, 1992; Caldwell and Collins, 1981; Smith and Brodie, 1982; Obst, 1986,1998; Alderton, 1988; [Sievert] and Sievert, [1988]; Dundee and Rossman, 1989; Ashton and Ashton, 1991; Carmichael and Williams, 1991; Ernst et al., 1994; Lamar, 1997; Conant and Collins, 1998; Powell et al., 1998; Bartlett and Bartlett, 1999a, b; Behler, 1999; Phillips et al., 1999; Johnson, 2000; Pough et al., 2001; Zug et al., 2001).

Size: 800 mm, record carapace length

Native Range: The indigenous range of M. temminckii encompasses eastern Texas, eastern Oklahoma, extreme southeastern Kansas and adjacent southwestern Missouri, the Mississippi River Valley of eastern Missouri up the valley northward through western Illinois, southern Indiana, and southeastern Iowa, western Kentucky and Tennessee (including disjunct populations in central Indiana and Tennessee), and other Gulf Coast drainages in Arkansas, Alabama, Louisiana, Mississippi, southwestern Georgia, and northern Florida as far south as the Santa Fe and Suwanee Rivers (Martof, 1956; Smith, 1961; Webb, 1970; Mount, 1975; Stevenson, 1976; Caldwell and Collins, 1981; Lohoefener and Altig, 1983; Garrett and Barker, 1987; Moler, 1988; [Sievert] and Sievert, [1988]; Carpenter and Krupa, 1989; Dundee and Rossman, 1989; Pritchard, 1989, 1992; Ashton and Ashton, 1991; Carmichael and Williams, 1991; Iverson, 1992; Lovich, 1993; Ernst et al., 1994; Conant and Collins, 1998; Heck, 1998; Bartlett and Bartlett, 1999a, b; Phillips et al., 1999; Dixon, 2000; Johnson, 2000; King, 2000). None of the river drainages inhabited by M. temminckii are Atlantic (Pritchard, 1989).

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

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Macrochelys temminckii are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AZ199719971Lower Salt
CA196820233Imperial Reservoir; Lower Sacramento; Russian
DC199419941Middle Potomac-Anacostia-Occoquan
MI199919991St. Joseph
OR201320131Upper Crooked
PR200720071Eastern Puerto Rico
VA202020201Middle Potomac-Anacostia-Occoquan

Table last updated 7/24/2024

† Populations may not be currently present.

Ecology: The best review of M. temminckii biology and natural history is by Pritchard (1989).

The Alligator Snapping Turtle is a massive, highly aquatic turtle that inhabits deep waters, primarily deep rivers with steep banks, but also lakes and swamps (Pritchard, 1989, 1992).

For the most part, M. temminckii is a carnivore that feeds primarily on fish, smaller turtles (especially kinosternids), crayfish, and mollusks (mussels and snails), but occasionally eats juvenile alligators, small mammals, ducks, amphibians, carrion, fruit, and acorns (Dundee and Rossman, 1989; Ernst and Barbour, 1989; Pritchard, 1989; Ernst et al. 1994; Conant and Collins, 1998). Although they actively forage for food along the bottom, they hunt for fish by lying still in ambush, with open mouth while wriggling the lure appendage on the tongue (Obst, 1986, 1998; Pritchard, 1989, 1992; Zug et al. 2001). Fish are trapped in their mouths in this fashion more commonly by smaller, younger turtles than by larger adults that spend more time actively foraging (Pritchard, 1989).  Females typically lay their eggs in loose, moist soil in or near river banks (Pritchard, 1989).

Means of Introduction: Probable pet releases.

Status: Inexplicably, the Alligator Snapping Turtle found in Washington, D.C., was scheduled to be "relocated" to Roosevelt Island or in waters along the George Washington Parkway, D.C., according to Park Ranger E. Broadbent (in Katz, 1994); still well away from its indigenous range.

Macrochelys temminckii collected from Michigan, California and Puerto Rico, and observed in Arizona are probably individual releases or escapees, and not known to represent breeding populations.

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: There are many myths about alligator snapping turtles attacking, even killing, humans; none of which are true (Pritchard, 1989). However, their strong jaws and sharp beaks make them potentially dangerous if carelessly handled. Pritchard (1989) verified that persons have had their fingers severed away cleanly; additionally, he demonstrated that the jaws of M. temminckii are formidable enough to break completely through the handles of the "flimsier" variety of brooms sold in modern supermarkets.

Alligator snapping turtles are exploited for their meat in parts of the rural South, and to a lesser extent by the pet trade (Dundee and Rossman, 1989; Pritchard, 1989; Sloan and Lovich, 1995); they are becoming scarce in parts of their indigenous range (Pritchard, 1989, 1992; Dixon, 2000). Macrochelys temminckii does not receive federal protection but does receive some kind of legal protection in various states (Pritchard, 1992; Levell, 1997).

The identity of M. temminckii found out of their indigenous range should be carefully verified as many untrained people mistake C. serpentina, the common snapping turtle, for this species (personal observation). The nonindigenous M. temminckii in Washington, D.C. (see above), which was scheduled for relocation in another part of D.C. by park rangers, is particularly suspicious.

References: (click for full references)

Alderton, D. 1988. Turtles & Tortoises of the World. Facts on File, Inc., New York. 191 pp.

Ashton, R. E., Jr., and P. S. Ashton. 1991. Handbook of Reptiles and Amphibians of Florida. Part Two. Lizards, Turtles & Crocodilians. Revised Second Edition. Windward Publishing, Inc., Miami. 191 pp.

Bartlett, R. D., and P. P. Bartlett. 1999a. A Field Guide to Florida Reptiles and Amphibians. Gulf Publishing Company, Houston. 280 pp.

Bartlett, R. D., and P. D. Bartlett. 1999b. A Field Guide to Texas Reptiles and Amphibians. Gulf Publishing Company, Houston. 331 pp.

Behler, J. L. 1999. National Audubon Society First Field Guide. Reptiles. Scholastic, Inc., New York. 160 pp.

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.

Brazo, M. 1999. Personal communication—Resident, Michigan.

Bury, R. B., and R. A. Luckenbach. 1976. Introduced amphibians and reptiles in California. Biological Conservation 1976(10):1-14.

Caldwell, J. P., and J. T. Collins. 1981. Turtles in Kansas. AMS Publishing, Lawrence, Kansas. 67 pp.

Carmichael, P., and W. Williams. 1991. Florida's Fabulous Reptiles and Amphibians. World Publications, Tampa. 120 pp.

Carpenter, C. C., and J. J. Krupa. 1989. Oklahoma Herpetology. An Annotated Bibliography. University of Oklahoma Press, Norman. 258 pp.

Carr, A. 1952. Handbook of Turtles. The Turtles of the United States, Canada, and Baja California. Comstock Publishing Associates, Ithaca and London. 542 pp.

Conant, R., and J. T. Collins. 1998. A Field Guide to Reptiles & Amphibians. Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin Company, Boston. 616 pp.

Crother, B.I. (chair). Committee on Standard and English and Scientific Names. 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and  Reptiles Herpetological Circular. No. 37. iii + 86p.

Demlong, M. 1997. Personal communication—Herpetologist, Phoenix Zoo, 455 N. Galvin Parkway, Phoenix, Arizona.

Dixon, J. R. 2000. Amphibians and Reptiles of Texas. Second Edition. Texas A & M University Press, College Station. 421 pp.

Dundee, H. A., and D. A. Rossman. 1989. The Amphibians and Reptiles of Louisiana. Louisiana State University Press, Baton Rouge and London. 300 pp + unattached erratum.

Ernst, C. H., and R. W. Barbour. 1972. Turtles of the United States and Canada. The University Press of Kentucky, Lexington. 347 pp.

Ernst, C. H., and R. W. Barbour. 1989. Turtles of the World. Smithsonian Institution Press, Washington, D.C. and London. 313 pp.

Ernst, C. H., J. E. Lovich, and R. W. Barbour. 1994. Turtles of the United States and Canada. Smithsonian Institution Press, Washington and London. 578 pp.

Garrett, J. M., and D. G. Barker. 1987. A Field Guide to Reptiles and Amphibians of Texas. Texas Monthly Press, Austin. 225 pp.

Heck, B. A. 1998. The alligator snapping turtle (Macroclemys temmincki) in southeast Oklahoma. Proceedings of the Oklahoma Academy of Science 78:53-58.

Iverson, J. B. 1992. A Revised Checklist with Distribution Maps of the Turtles of the World. John B. Iverson, Richmond, Indiana. 363 pp.

Iverson, J. [B.], P. [A.] Meylan, and M. [E.] Seidel. 2000. Testudines—turtles. Pp. 75-82. In: B. I. Crother (chair), and Committee on Standard English and Scientific Names (editors). Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and Reptiles Herpetological Circular (29):i-iii, 1-82.

Johnson, T. R. 2000. The Amphibians and Reptiles of Missouri. Revised and Expanded Second Edition. Missouri Department of Conservation, Conservation Commission of the State of Missouri, Jefferson City. 400 pp.

King, F. W. 2000. Florida Museum of Natural History's Checklist of Florida Amphibians and Reptiles [online]. Florida Museum of Natural History, University of Florida, Gainesville. Available on URL: http://www.flmnh.ufl.edu/herps/FL-GUIDE/Flaherps.htm.

King, F. W., and R. L. Burke (editors). 1989. Crocodilian, Tuatara, and Turtle Species of the World. A Taxonomic and Geographic Reference. The Association of Systematics Collections, Washington, DC. 216 pp.

Katz, C. 1994. Mall safari bags snapping turtle. The Washington Times 1994(8 August):C4.

Lamar, W. W. 1997. The World's Most Spectacular Reptiles & Amphibians. World Publications, Tampa. 210 pp.

Levell, J. P. 1997. A Field Guide to Reptiles and the Law. Second Revised Edition. Serpent's Tale Natural History Book Distributors, Lanesboro, Minnesota. 270 pp.

Lohoefener, R., and R. Altig. 1983. Mississippi herpetology. Mississippi State University Research Center Bulletin (1):i-vi, 1-66.

Lovich, J. E. 1993. Macroclemys. Catologue of American Amphibians and Reptiles (562):1-4.

Martof, B. S. 1956. Amphibians and Reptiles of Georgia. University of Georgia Press, Athens, Georgia. 94 pp.

Moler, P. 1988. A Checklist of Florida's Amphibians and Reptiles. Nongame Wildlife Program, Florida Game and Fresh Water Fish Commission, Tallahassee. 18 pp.

Mount, R. H. 1975. The Reptiles and Amphibians of Alabama. Auburn University Agricultural Experiment Station, Auburn. 347 pp.

Obst, F. J. 1986. Turtles, Tortoises and Terrapins. St Martin's Press, New York. 231 pp.

Obst, F. J. 1998. Turtles & tortoises. Pp. 108-125. In: H. G. Cogger and R. G. Zweifel (editors). Encyclopedia of Amphibians & Reptiles. Second Edition. Academic Press, San Diego. 240 pp.

Phillips, C. A., R. A. Brandon, and E. O. Moll. 1999. Field Guide to Amphibians and Reptiles of Illinois. Illinois Natural History Survey, Champaign, Illinois. 282 pp.

Pope, C. H. 1939. Turtles of the United States & Canada. Alfred A. Knopf, New York. 343 + v pp. (Reprinted 1971.)

Pough, F. H, R. M. Andrews, J. E. Cadle, M. L. Crump, A. H. Savitzky, and K. D. Wells. 2001 [2000]. Herpetology. Second Edition. Prentice Hall, Upper Saddle River, New Jersey. 612 pp.

Powell, R., J. T. Collins, and E. D. Hooper, Jr. 1998. A Key to Amphibians & Reptiles of the Continental United States and Canada. University Press of Kansas, Lawrence. 131 pp.

Pritchard, P. C. H. 1979. Encyclopedia of Turtles. T.F.H. Publications, Inc., Neptune, New Jersey. 895 pp.

Pritchard, P. C. H. 1989. The Alligator Snapping Turtle. Biology and Conservation. Milwaukee Public Museum, Milwaukee. 104 pp.

Pritchard, P. C. H. 1992. Alligator snapping turtle. Macroclemys temminckii (Harlan). Pp. 171-177. In: P. E. Moler (editor). Rare and Endangered Biota of Florida. Volume III. Amphibians and Reptiles. University Press of Florida, Gainesville, Florida. 292 pp.

[Sievert], G., and L. Sievert. [1988]. A Field Guide to Reptiles of Oklahoma. Oklahoma Department of Wildlife Conservation, Oklahoma City. 96 pp.

Sloan, K., and J. E. Lovich. 1995. Exploitation of the alligator snapping turtle, Macroclemys temminckii, in Louisiana: A case study. Chelonian Conservation and Biology 1(3):221-222.

Smith, H. M., and E. D. Brodie, Jr. 1982. A Guide to Field Identification. Reptiles of North America. Golden Press, New York. 240 pp.

Smith, P. A. 1961. The amphibians and reptiles of Illinois. Illinois Natural History Survey Bulletin 28(1):[i-v], 1-298. (Reprinted 1986.)

Stevenson, H. S. 1976. Vertebrates of Florida. Identification and Distribution. University Presses of Florida, Gainesville. 607 pp.

Webb, R. G. 1970. Reptiles of Oklahoma. University of Oklahoma Press, Norman. 370 pp.

Webb, R. G. 1995. The date of publication of Gary's Catalogue of Shield Reptiles. Chelonian Conservation and Biology 1(4):322-323.

Zug, G. R., L. J. Vitt, and J. P. Caldwell. 2001. Herpetology. An Introductory Biology of Amphibians and Reptiles. Second Edition. Academic Press, San Diego. 630 pp.

Other Resources:
Great Lakes only fields posted 12/5/2022.  Shared fields sent to J. Freedman for review.

Author: Pam Fuller, Louis A. Somma and Courtney Cameron

Revision Date: 1/17/2024

Citation Information:
Pam Fuller, Louis A. Somma and Courtney Cameron, 2024, Macrochelys temminckii (Troost in Harlan, 1835): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1227, Revision Date: 1/17/2024, Access Date: 7/25/2024

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.


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Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [7/25/2024].

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