Alligator Snapping Turtle
Macroclemys temminckii
The alligator snapping turtle is an aquatic turtle with a sharp, hooked beak. This turtle spends most of its time in deep water. Its habitat includes sloughs and deep muddy pools of large rivers. Water pollution, habitat alteration, a reduction in egg-laying sites and over-harvesting have probably all had a part in causing the decline of this species. The species is listed RARE by the Missouri Department of Conservation.
Identification
The alligator snapping turtle can be identified by the three prominent ridges on the upper shell (carapace). The tail is long and muscular. Numerous fleshy projections can be found on the skin of the head, neck and front legs. The webbed toes are equipped with large, strong claws.
The reduced lower shell (plastron) is probably the result of the turtle's special head-thrusting and snapping movements. Adult alligator snapping turtles range in shell length from 15 to 26 inches.
A snapping turtle's weight may range from 35 to 105 pounds. The largest alligator snapping turtle found in Missouri weighed 128 pounds. This is the largest freshwater turtle species in the world.
Adults have dark brown heads, legs and shells. The skin on the neck and other areas may be yellowish brown. Males have longer tails than females and are at least twice their weight.
For a technical description of this animal, refer to: Ernst, C., J. Lovich, and R. Barbour. 1994. Turtles of the United States. Smithsonian Institution Press. Washington, DC.
Life History
This species is unique in being able to use its tongue as a lure to entice fish into its mouth. The alligator snapping turtle feeds mainly on fish, but will also capture and eat small turtles. Alligator snapping turtles are sexually mature between 11 and 13 years of age. Courtship probably begins in late spring. Females lay 16 to 56 eggs during May and June.
Eggs are round, white and hard-shelled. Hatching probably occurs in late summer. Females may produce eggs only every other year.
The alligator snapping turtle seldom comes out of the water to bask in the sun. Females will leave the water to find an egg-laying site. Most of their time is spent in deep water in mud and hiding among root snags. They are active at night. Their method of moving is by walking rather than swimming.
This large snapping turtle is generally viewed as a predator rather than prey. Although not a serious threat to each other, males will engage in fierce fights.
Habitat and Distribution
The alligator snapping turtle is found in southern, southeastern and
eastern Missouri.
The alligator snapping turtle can be found in southern, south-eastern and eastern Missouri. There is only one record of this turtle for the Missouri River in Missouri.
The alligator snapping turtle is confined to the Gulf of Mexico drainages of the United States and is widespread in the lower Mississippi valley.
Cause of Historic Decline
Some hatchlings of alligator snapping turtles were collected for the pet trade. Larger specimens were exploited for meat in local areas. Over-harvesting has eliminated several populations. The large shells were often used for exhibit purposes.
Current Threats to Alligator Snapping Turtles
- Habitat loss - Construction of dams and other alterations in major rivers has created barriers to turtles migrating to suitable breeding habitat. Removal of log jams in rivers removes the hiding and hunting areas used by snapping turtles. River flooding can destroy most eggs in some years.
- Dredging - Dredging material can make excellent nesting habitat if these areas are above the average flood-line. Material dumped on existing nests will destroy the eggs.
- Harvest and overharvest - Over-harvesting for turtle meat and the pet trade must be regulated. Harvest of alligator snapping turtles is not allowed in Missouri. Snapping turtles suffer losses from incidental illegal take by anglers and commercial fishermen. Unbaited, unmarked and abandoned setlines and trotlines pose a threat to all species of aquatic turtles including alligator snapping turtles. Trotlines must be labeled in Missouri, but often are not. Turtles can take the bait on trotlines. They also get hooked on the limbs, neck, or edge of the shell on abandoned trotlines and drown.
Protection and Management: Steps Toward Recovery
- Habitat protection - In Missouri, the alligator snapping turtle is not on the brink of extinction but is in low numbers and in need of protection. The species' aquatic habitat must be protected and improved. The construction of dams should be avoided to allow this species free movement along streams. This will likely avoid flooding of nest sites as well. Some log jams should be left in streams to provide habitat for this species.
- Dredging - Stream alteration should be avoided to protect turtle habitat. If dredging is needed, material should be dumped away from potential turtle nesting sites or dumped prior to egg laying in May and early June.
- Fishing pressure/over-harvesting - Abandoned trotlines in rivers, streams or reservoirs must be avoided. Use hooks other than stainless steel, due to stainless steel's high resistance to corrosion and long life on an abandoned trotline. Many turtles become caught or entangled in abandoned lines. Do not participate in collecting turtles for commercial trade.
- State and Federal agencies - Research is needed to determine the movements and survivorship of this turtle. A mark-recapture study is being done to collect information on habitat selection and movement in southeast Missouri.
Alligator snapping turtle habitat can be protected through the purchase of land or acquisition of easements to protect streams and wetlands.
Federal regulations are needed to further restrict the commercialization of this unique species. More enforcement of trotline labeling and checking is needed. Posters explaining the concern should be posted at boat landings. Setlines and trotlines could be prohibited in areas of critical habitat.
Missouri and federal law prohibits the importation, transportation, sale, purchase, taking or possession of animals on the State or Federal lists.
For more information on the alligator snapping turtle, or to report sightings of this species, contact:
Endangered Species Coordinator or HerpetologistMissouri Department of Conservation
P.O. Box 180
Jefferson City, MO 65102
573/ 751-4115
