The alligator snapping turtle is a huge aquatic species with a noticeably large head (as compared to other species of turtles). The carapace (upper shell) has 3 prominent ridges — 1 along the center line and 1 on either side. There is an extra row of scutes (horny scales) on each side of the carapace. The large head terminates in a sharp, strongly hooked beak. The tail is long and muscular, with smooth, round bumps. The skin on the head, neck, and forelimbs has a number of fleshy projections or tubercles. The lower shell (plastron) is relatively small and affords little protection to the animal's underside. Adults have dark brown heads, limbs, and shells; the skin on the neck and other areas may be yellowish brown. Adults have dark brown heads, limbs, and shells; the skin on the neck and other areas may be yellowish brown.
Similar species: The eastern snapping turtle (Chelydra serpentina) is more common and widespread in our state. Adults have a more rounded shell, lacking the 3 prominent ridges described for the alligator snapping turtle. Also, the head is often covered with numerous small black lines or spots. Underparts are yellowish-white. The upper part of the tail has large, pointy scales in a sawtoothed row. The eyes can be seen from above.
The alligator snapping turtle is the only member of its genus that occurs in Missouri. Globally, the only other species of alligator snapping turtle (genus Macrochelys) is the Suwannee snapping turtle (M. suwanniensis), which is restricted to the Suwannee River basin in Georgia and Florida. A proposed third species in the genus, the so-called Apalachicola snapping turtle (M. apalachicolae), has not been universally accepted as a distinct species. Two more species in the genus are extinct and known only from fossils. All in the genus are endemic to North America.
Adult upper shell length: 15–20 inches, occasionally to more than 30 inches; weight 35–150 pounds, with a record weight of more than 250 pounds. Males attain greater sizes and have longer tails than females.
In Missouri, mainly occurs in the large rivers, sloughs, and oxbow lakes of southern, southeastern, and eastern Missouri.
Habitat and Conservation
The preferred habitats include deep sloughs, oxbow lakes, and deep pools of large rivers. Other habitats include reservoirs and upland Ozark streams. Movements of this turtle species throughout the river channel can be extensive; an individual can range across more than 15 miles along a river over a three-year period.
This species is totally aquatic and seldom climbs out of the water to bask in the sun. Most individuals seen out of water are apparently females seeking an egg-laying site. Otherwise, they spend most of their time in deep water, hiding in root snags or among submerged logs. They spend daylight hours in hiding and become active at night. This species seldom attempts to swim; it normally moves about by slowly walking on the bottom of a body of water.
It appears the alligator snapping turtle cannot remain submerged for long periods of time, as some other aquatic turtle species can, especially in warm water. At a water temperature of 70°F, specimens were unable to remain underwater for longer than 50 minutes without surfacing to breathe. They typically extend their necks to reach slightly above the water surface to breathe.
Mainly fish, but also small turtles, snakes, small mammals, crayfish, mollusks, and even nuts and fruits such as acorns, hickory and pecan nuts, and persimmons.
Young alligator snappers eat a variety of small aquatic prey, such as small fish, aquatic insects, crayfish, mussels, and snails.
This species is unique among North American turtles in having the ability to lure fish to its mouth. Its tongue has a special appendage shaped like a stout worm; it can be moved at will by the turtle while it lies motionless on the bottom of a river of slough. Fish are attracted to the wriggling “worm” and are captured and eaten when they venture too close.
A species of conservation concern in Missouri. Imperiled in Missouri, apparently secure globally. It is unlawful to capture, kill, or collect alligator snapping turtles in this state. If you are fishing, check your limb lines and trotlines daily; if you catch one of these rare turtles, you must release it unharmed.
Past overharvesting, water pollution, bycatch from fishing gear, and extensive habitat alteration are the main reasons for the decline of this species. However, it appears that this species is expanding its range within the state, especially with the increased reports within reservoirs and upland Ozark streams in the southern part of the state.
Raccoon predation of nests and drowning of individuals snagged on limb lines and trotlines are likely the primary threats this species faces today in Missouri.
Courtship and breeding take place in water and mainly in springtime. Females emerge from the water, apparently at night, during late April through June, to dig a nest and lay eggs. The nest digging, egg depositing, and nest covering can be accomplished within 4 hours.
Clutch size may be some 9–61 eggs, with an average of 28. The eggs are spherical, white, and have a rough, leathery shell. Hatching probably takes place in late summer, after an incubation period of 80–114 days.
Individuals usually become sexually mature between 11 and 13 years of age, though some individuals can take as long as 21 years to mature. There is evidence that some adult females may only produce eggs every other year instead of annually. Lifespan can be up to 70 years.
In the past, alligator snapping turtles served humans in many ways, providing their bodies as meat and as pets, and their shells as conversation pieces. Today, their alarming decline is a call for us to serve the snappers by working to restore their numbers.
It is unlawful to capture, kill, or collect alligator snapping turtles in this state. Past overharvesting, water pollution, bycatch from fishing gear, and extensive habitat alteration are the main reasons for the long-term decline of this species. Drowning due to being snagged on limb lines and trotlines is today one of the primary threats to this species in Missouri.
The species name, temminckii, honors Coenraad Jacob Temminck (1778–1858), a zoologist and the founding director of the National Museum of Natural History in Leiden, the Netherlands. He served in that position from 1820 until his death. Dozens of species were named in his honor, including 10 fishes (one of which is the kissing gourami, a tropical fish well-known in pet shops), bats, squirrels, mice, a monkey, a whale, a shark, 20 birds, an Indonesian skink, and more. His 1815 manual of European birds was the standard reference to the birds of that continent for many years.
These turtles help to keep the populations of many aquatic animals in check. Meanwhile, despite the ability of adults to defend themselves, eggs and nests are very vulnerable to predators such as skunks and raccoons.
The snapping turtle family (Chelydridae) comprises six species representing two genera (Chelydra and Macrochelys); this family is restricted to North and South America. Members of this family have large heads, powerful jaws, and small plastrons (lower shells) that restrict them from pulling in their heads and limbs for complete protection. They are not great swimmers and prefer to walk on the bottom of freshwater wetlands. Members of genus Chelydra, called “snapping turtles,” range from Canada through the eastern and central United States and south to Ecuador. Members of genus Macrochelys, called “alligator snapping turtles,” occur in southeastern and southern states; they are the largest freshwater turtles in the world.
Turtles and tortoises represent the oldest living group of reptiles on earth. These generally hard-shelled reptiles are known from fossils as far back as the Triassic Period — over 200 million years ago — and have changed very little since they became established.
All turtles and tortoises belong to the Order Testudines, with 341 living species in 14 genera. Most people are familiar with the general characteristics of turtles, and they are seldom confused with other animals. However, few people are aware of the natural history, habitat requirements, population status, or distribution of even the most common species of turtles.