Alligator Snapping Turtle

Maximum longevity: 70.3 years (captivity)

Alligator snapping turtles are threatened by human exploitation in all U.S. states, but especially in Louisiana. In 1991 the U.S. Fish and Wildlife Services (USFWS) nominated alligator snapping turtles as a candidate to be placed on the Endangered Species list, but the USFWS later concluded in 1999 that they did not warrant protection under the Endangered Species Act. In 2004 the state of Louisiana put a ban on the commercial harvest of M. temminckii anywhere in the state.

US Federal List: no special status

CITES: appendix iii

IUCN Red List of Threatened Species: vulnerable

The only known predators of adults are humans, but eggs and hatchlings are a source of food for large fish, raccoons, and birds.

Known Predators:

• humans (Homo sapiens)
• raccoons (Procyon lotor)
• predatory fish (Actinopterygii)
• large birds (Aves)

Anti-predator Adaptations: cryptic

Alligator snapping turtles are the largest freshwater turtles in the world. They are characterized by three large, pronounced ridges that run from the front to the back of their carapace. They have powerful jaws, large heads, and are unique among snapping turtles for having eyes on the side of their heads. Alligator snapping turtles are primitive in appearance.

Range mass: 70 to 80 kg.

Range length: 79 to 101 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: male larger

Males live from 11 to 45 years with an average age of 26 years. Females live from 15 to 37 years with an average of 23 years. Alligator snapping turtles can live a very long time in captivity; the oldest known individual in captivity was 70 years old.

Range lifespan
Status: wild: 11 to 45 years.

Range lifespan
Status: captivity: 70 (high) years.

Typical lifespan
Status: wild: 11 to 45 years.

Average lifespan
Status: captivity: 70.3 years.

Alligator snapping turtles live in freshwater areas in the southeastern United States. They generally live in the deepest water within their habitat: large rivers, canals, lakes, swamps, and rivers. Hatchlings and juveniles usually live in smaller streams.

Habitat Regions: temperate ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams

Wetlands: marsh ; swamp

Macrochelys temminckii is found from northern Florida to southern Georgia and through the Gulf states into Texas. They are also found as far north as Illinois and Kansas. All stable populations are found around larger bodies of water such as the Mississippi River.

Biogeographic Regions: nearctic (Native )

Alligator snapping turtles are both scavengers and active hunters. They are most active at night, during the day they lie quietly at the bottom of murky water and open their jaws to reveal their tongue, which looks like a small pink worm-like lure in the back of their gray mouth. The lure attracts fish, which are then either swallowed whole, sliced in two by their sharp jaws, or impaled on the sharp tips of the upper and lower jaws. Alligator snapping turtles most frequently feed on fish, molluscs and other turtles. In a Louisiana study turtles were found in the stomachs of 79.82% of all alligator snapping turtles. Macrochelys temminckii have been recorded eating frogs, snakes, snails, worms, clams, crayfish, insects and aquatic plants. They have even been known to eat medium-sized rodents, such as nutria (Myocastor coypus), squirrels, and muskrats (Ondatra zibethicus), and other medium-sized mammals, including opossums (Didelphis virginianus), raccoons (Procyon lotor), and armadillos (Dasypus novemcinctus). The main source of their diet, however, seems to be fish. These turtles feed year-round by taking advantage of warm winter days to search for food in the water and along the shoreline.

Animal Foods: birds; mammals; reptiles; fish; carrion ; insects; mollusks; aquatic crustaceans

Plant Foods: leaves; roots and tubers; wood, bark, or stems; seeds, grains, and nuts

Primary Diet: carnivore (Piscivore )

Alligator snapping turtles are both major predators and opportunistic scavengers in their environment. These turtles can impact fish species as well as other turtle species due to their large food consumption, while also helping to clean up decaying organisms in their habitat.

Ecosystem Impact: biodegradation

Alligator snapping turtles play a role in freshwater ecosystems. Adults are not a source of food for any animals other than humans, but eggs and hatchlings are a source of food for large fish, racoons, and birds. Adults are important predators. Humans find them valuable for their unique appearance and their meat.

Positive Impacts: food

Alligator snapping turtles have a dangerous bite, but generally don't attack humans unless provoked.

Negative Impacts: injures humans (bites or stings)

Alligator snapping turtle hatchlings look very similar to adults. Sex is determined by incubation temperature. Warm temperatures of 29 to 30 degrees Celsius produce 100% females, while slightly lower temperatures (25 to 27 degrees Celsius) yield predominantly males. All other temperatures allow both to develop. Eggs are fertile if they have a clear subgerminal space or if a chalky white spot is on the eggshell.

Development - Life Cycle: temperature sex determination

Alligator snapping turtles use chemosensory cues to locate prey items. They use gular (throat) pumping to draw water in and out to sample the surrounding water for chemicals that have been released by prey species. Adult snapping turtles use this sensory system to hunt and locate mud and musk turtles (Kinosternidae) that have buried themselves into the mud bottom of a body of water.

Communication Channels: visual ; chemical

Perception Channels: visual ; chemical

There is an unverified legend that a 403 lb alligator snapping turtle was found in the Neosho River in Kansas in 1937.

During mating, male alligator snapping turtles mount the back of the female. He grasps her shell with all four feet to inseminate.

Mating System: polygynandrous (promiscuous)

It is unlikely that females reproduce more than once a year, some females lay eggs on an alternate-year basis. These turtles mate in early spring in Florida and late spring in the Mississippi Valley. They lay eggs in a nest about two months later in a nest hole dug approximately 50 m from a body of water. All nests are dug in the sand and clutch success is highly variable. A clutch may contain 8 to 52 eggs and incubation takes 100 to 140 days. Hatchlings emerge in the fall. Sexual maturity is reached by both sexes at 11 to 13 years of age.

Breeding interval: Alligator snapping turtles breed once yearly.

Breeding season: These turtles mate in early spring in Florida and late spring in the Mississippi Valley.

Range number of offspring: 8 to 52.

Range gestation period: 100 to 140 days.

Range age at sexual or reproductive maturity (female): 11 to 13 years.

Range age at sexual or reproductive maturity (male): 11 to 13 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

Average number of offspring: 30.

Besides the act of mating, males invest no additional time or energy towards parenting. Once females dig a nest and lay eggs (9 to 52 per clutch), they invest no additional resources. Juvenile turtles are independent upon hatching.

Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)

The alligator snapping turtle is a solitary species, which mates in the early spring in Florida, later spring in the Mississippi Valley, and nests about 2 months later (8) (9). Nests are dug at least 50 m from the water's edge, into which 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 (11). 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, the dark colouring of its mouth-lining and exterior, which is coated in 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 fish 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).

Collecting wild specimens is prohibited in Arkansas, Florida, Georgia, Indiana, Missouri, Tennessee, but allowed with the necessary permit in Alabama, Illinois, Kansas, Louisiana, Oklahoma and Texas. The alligator snapping turtle has been found in reservoirs throughout its range, and dyking 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).

Amongst the largest freshwater turtles in the world, the alligator snapping turtle is a prehistoric-looking species with a reputation as the 'dinosaur of the turtle world' (2). Its camouflaged, ridged upper shell (carapace), large head, powerful, hooked, beak-like jaws, thick, scaled skin and oversized claws all contribute to this species' primitive look and set it apart from other freshwater turtles (4) (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 (2) (6). The shell also often has algae growing on it, which adds to the snapping turtles' 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 to it; the tongue contains a small, pink, worm-like projection (lure), which is grey at rest but suffused with blood when active, and wriggled to attract prey into the turtle's mouth (2).

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).

Endemic to the southeastern region of the U.S., occurring in the river system that drains into the Gulf of Mexico (1) (2) (9).

Classified as Vulnerable (VU) on the IUCN Red List 2006 (1) and listed on Appendix III of CITES (3).

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 of the U.S. (8) (12). Although some states now prohibit collection of this species, other states allow it with permits (13). Other threats to this turtle include habitat destruction and alteration, water pollution and pesticide accumulation (1) (9) (13).

Continent: North-America
Distribution: USA (Mississippi valley, Kansas, SE Iowa, Illinois, W Tennessee, W Kentucky, Missouri, Oklahoma, E Texas, Arkansas, Louisiana, Mississippi, Alabama, SW Georgia, N Florida)
Type locality: "a tributary stream of the Mississippi, which enters that river above Memphis, in West Tennessee," U.S.A.; restricted to the Wolf River, Shelby County, Tennessee, USA., by Bour 1987.

The Apalachicola snapping turtle (Macrochelys apalachicolae) is a proposed species that lives in the Apalachicola River, United States. The species can as well be found within other panhandle rivers within the states of Florida, Georgia, and Alabama. It has traditionally been included as part of the widespread species M. temminckii, but an analysis in 2014 recommended treating it as distinct. A study published the following year considered this change unwarranted and recommended that M. apalachicolae should be considered a junior synonym of M. temminckii, and this is followed by the Reptile Database, IUCN's Tortoise and Freshwater Turtle Specialist Group, and the Committee On Standard English And Scientific Names (Society for the Study of Amphibians and Reptiles). The Apalachicola snapping turtles and other species of snapping turtle have been classified as endangered due to human activity which is causing the destruction to their natural habitats