Alligator snapping turtle  (Macrochelys temminckii)

The alligator snapping turtle is classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix III of CITES (3).

One of the largest freshwater turtles in the world, the alligator snapping turtle (Macrochelys temminckii) is a prehistoric-looking species with a reputation as the ‘dinosaur of the turtle world’ (4). It has a camouflaged, ridged upper shell (carapace), a large head and powerful, hooked, beak-like jaws, which, together with its thick, scaly skin and oversized claws, all contribute to its primitive look and set it apart from other freshwater turtles (5). The three large, pronounced ridges running down the length of the dark brown to blackish shell somewhat resemble those on the back of an alligator, and earn the species its common name (4) (6). The shell also often has algae growing on it, which adds to the snapping turtle’s camouflage (6). The tail is almost as long as the shell itself and, together with the chin, throat and neck, is coated with long, pointed tubercles (7) (8). The alligator snapping turtle has an unusual way of luring prey; the tongue contains a small, pink, worm-like projection (lure), which is grey at rest but suffused with blood when active, and is wriggled to attract prey into the turtle’s mouth (4).

Endemic to the southeastern region of the United States, occurring in all the river systems that drain into the Gulf of Mexico (1) (4) (9).

A freshwater species generally found in the deep water of large rivers, canals, lakes and swamps, though hatchlings and juveniles usually live in small streams (9). These turtles seldom leave the water, with generally only nesting females venturing onto land, although males have been known to bask (10).

The alligator snapping turtle is a solitary species, which mates in the early spring in Florida, or later in spring in the Mississippi Valley, and nests about two months later (8) (9). Nests are dug at least 50 metres from the water’s edge, and a clutch containing anything between 8 and 52 eggs may be laid (9). Incubation lasts 100 to 140 days and most hatchlings emerge in September or October (8) (9). As with a number of reptiles, the sex of the young is determined by incubation temperature; high and low temperatures yield more females and moderate temperatures yield more males. Sexual maturity is attained between 11 and 13 years of age, and alligator snapping turtles have been known to live up to 70 years in captivity, although the lifespan in the wild is unknown (10).

The alligator snapping turtle actively forages for food at night, but is more of a ‘sit-and-wait’ predator during the day. The turtle lies quietly on the mud bottom with its jaws wide open, its dark colouring and its coating of algae making it almost invisible to fish (9). The worm-like lure within the turtle’s mouth is wiggled to entice unwary fish and, when the unlucky prey comes close, the turtle’s jaws are quickly snapped shut (6) (9). The alligator snapping turtle not only feeds on a variety of fish, but also on frogs, snakes, snails, worms, clams, crayfish, aquatic plants and even other turtles (9).

A major decline in numbers occurred as a result of over-collection by one of the major soup manufacturing companies in the U.S., and alligator snapping turtles are still threatened by over-harvesting for their meat in many areas (8) (11). Although some states now prohibit collection of this species, other states allow it with permits (12). Other threats to this turtle include habitat destruction and alteration, water pollution and pesticide accumulation (1) (9) (12).

Collecting wild specimens is prohibited in Arkansas, Florida, Georgia, Indiana, Missouri and Tennessee, but allowed with the necessary permit in Alabama, Illinois, Kansas, Louisiana, Oklahoma and Texas (1). The alligator snapping turtle has been found in reservoirs throughout its range, and diking of rivers to create winter waterfowl refuges has increased the available habitat in Arkansas and the lower Mississippi Valley, which may help offset some of the habitat degradation and loss seen elsewhere (1).

View information on this species at the UNEP World Conservation Monitoring Centre.

For more information on the alligator snapping turtle see:

• The Centre for Reptile and Amphibian Conservation and Management:
  http://herpcenter.ipfw.edu/
• Ernst, C.H., Altenburg, R.G.M. and Barbour, R.W. (1997) Turtles of the World. ETI Information Systems Ltd, Netherlands. Available at:
  http://nlbif.eti.uva.nl/bis/turtles.php