Macrochelys temminckiiAlligator Snapping Turtle

Geographic Range

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. (Minton Jr., 2001; Minton Jr., 2001; Conant, et al., 1992; Ernst, et al., 1994)

Habitat

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. (Ernst, et al., 1994)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Physical Description

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. (Conant, et al., 1992; Ernst, et al., 1994)

  • Sexual Dimorphism
  • male larger
  • Range mass
    70 to 80 kg
    154.19 to 176.21 lb
  • Range length
    79 to 101 cm
    31.10 to 39.76 in

Development

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. (Ernst, et al., 1994; Pritchard, 1979)

  • Development - Life Cycle
  • temperature sex determination

Reproduction

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

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. (Ernst, et al., 1994; Pritchard, 1979)

  • 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
  • Average number of offspring
    30
    AnAge
  • 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

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. (Conant, et al., 1992)

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

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. ("The Alligator Snapping Turtle", 2007)

  • 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
    AnAge

Behavior

Alligator snapping turtles spend most of their time in the water, generally only nesting females venture on land. They are solitary and there is little social structure and no parental care. These turtles stay submerged for 40 to 50 minutes at a time and only go to the surface for air. They are so motionless under water that algae can cover their backs and make the turtles almost invisible to fish. (Ernst, et al., 1994)

A study by Riedle et al. (2006) in Oklahoma radio-tagged adult turtles, and found that they prefer areas with submerged cover (logs, overhanging shrubs, occasional beaver dens) combined with high percentage of overhead canopy. The study also suggested that turtles thermoregulate using differing stream depths seasonally. For example, they chose deeper water during midwinter and shallower water in the early summer months. (Riedle, et al., 2006)

  • Average territory size
    777.8 m^2

Home Range

Riedle et al. (2006) found that Oklahoma populations of alligator snapping turtles have an average linear home range of 777.8m. Females on average have a home range of 878.3m +/- 298.4m, while males on average have a home range of 481.4m +/- 227.7m. Juveniles have larger home ranges than both adult males and female. On average a juvenile turtle's home range is 1,073.3m +/- 1,015.4m. This is considerably larger than both home range size of adult makes and females. Adult turtles have been found to use submerged structures as a core feature of their home range and have been found to stay 12.3 days on average in each core home range. (Riedle, et al., 2006)

Communication and Perception

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. (Punzo and Alton, 2002)

Food Habits

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. (Elsey, 2006; Ernst, et al., 1994; Pritchard, 1979)

  • 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

Predation

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

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

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. (Conant, et al., 1992)

Economic Importance for Humans: Positive

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. (Ernst, et al., 1994)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

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

  • Negative Impacts
  • injures humans
    • bites or stings

Conservation Status

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. (Elsey, 2006)

Other Comments

There is an unverified legend that a 403 lb alligator snapping turtle was found in the Neosho River in Kansas in 1937. (Ernst, et al., 1994)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Matt Nichols (author), Radford University, Joseph Pruitt (author), Radford University, DD Munsey (author), Radford University, Garrett Good (author), Radford University, Beth Meyer (author), Radford University, Kelle Urban (author), Radford University, Karen Francl (editor, instructor), Radford University.

Paul DiLaura (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

biodegradation

helps break down and decompose dead plants and/or animals

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

visual

uses sight to communicate

References

2007. "Alligator Snapping Turtle" (On-line). National Geographic. Accessed August 22, 2007 at http://animals.nationalgeographic.com/animals/reptiles/alligator-snapping-turtle.html.

2007. "Smithonian National Zoological Park" (On-line). Reptile and Amphibians; Facts Sheet. Accessed August 28, 2007 at http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Alligatorsnappingturtle.cfm.

Division of Scientific Authority United States Fish and Wildlife Service. The Alligator Snapping Turtle. 10-21-RR267-154. Aiken, SC: Savannah River Ecology Laboratory. 2007.

Chicago Zoological Society, 2007. "Brookfield Zoo Feild Guide" (On-line). Accessed September 04, 2007 at http://www.brookfieldzoo.org/pagegen/htm/fix/fg/fg_body.asp?sAnimal=Alligator+snapping+turtle.

Conant, R., R. Stebbins, J. Collins. 1992. Peterson First Guide to Reptiles and Amphibians. New York, New York: Houghton Mifflin Company.

Elsey, R. 2006. Food Habits of Macrochelys temminckii (Alligator Snapping Turtle) From Arkansas and Louisiana. Southeastern Naturalist, 5: 443-452.

Ernst, C., R. Barbour, J. Lovich. 1994. Turtles of the United States and Canada. Washington, D.C.: Smithsonian Institution Press.

Harrel, J., N. Douglas, M. Haraway, R. Thomas. 1996. Mating Behavior In Captive Alligator Snapping Turtles (Macroclemys temminckii). Chelonian Conservation and Biology, 2: 101-105.

Minton Jr., S. 2001. Amphibians & Reptiles Of Indiana. Indianapolis: Indiana Academy of Science.

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

Punzo, F., L. Alton. 2002. Evidence for the Use of Chemosensory Cues by the Alligator Snapping Turtle, Macroclemys temminckii, to Detect the Presence of Musk and; Mud Turtles. Florida Scientist, vol. 65/ no.2: 134-138.

Riedle, J., P. Shipman, S. Fox, D. Leslie Jr.. 2006. Microhabitat use, Home Range, and Movements of the Alligator Snapping Turtle, Macrochelys temminckii, in Oklahoma. The Southwestern Naturalist, vol.51/ iss.1: pp.35-40.