Snapping Turtle
Chelydra serpentina

Common Name:

Snapping Turtle

Scientific Name:

Chelydra serpentina

Etymology:

Genus:

Chelydra is derived from the Greek word chelydra which means "tortoise".

Species:

serpentina is derived from the Latin word serpentis meaning "snake". Referring to the long tail of the turtle.

Average Length:

8 - 14 in. (20.3 - 36 cm), weight 10 - 35 lbs. (4.5 - 16 kg)

Virginia Record

18 1/3 in. (46.5 cm). 51 lbs.(23.13 kg)

Record length:

19.4 in. (49.4 cm), wild caught weight 75 lbs. (34 kg), captive weight 86 lbs. (39 kg)

Systematics: Described originally as Testudo serpentina by Carolus Linnaeus in 1978, based on a museum specimen in Stockholm, Sweden. The type locality was listed as "Caldis regionibus" but it was later restricted to New Orleans, Louisiana, by Smith and Taylor (1950) and the vicinity of New York City by Schmidt (1953). Chelydra was first used for this species by Schweigger (1812).

This species has often been called the Common Snapping Turtle (e.g., Collins, 1997, SSAR Herpetol. Circ. 25). We have dropped the adjective because it might be misinterpreted as referring to the abundance of the species rather than to its being the typical, most widespread species of its family. Shaffer et al. (2008; Biology of the Snapping Turtle, John Hopkins Univ. Press.) provided convincing genetic evidence that C. serpentina is a “single, virtually invariant lineage” and hence abandoned the recognition of the subspecies C. s. osceola Stejneger, 1918.

Description: A large freshwater turtle reaching a maximum straight-line carapace length (CL) of 494 mm (19.4 inches) (Conant and Collins, 1991). In Virginia, known maximum adult CL is 18 1/3 in. (46.5 cm), maximum plastron length 32.4 cm, and maximum body mass is 51 lbs. (23.13 kg).

Morphology: Carapace flattened with 3 knobby keels that become smooth with age; posterior margin of carapace strongly serrated; last 4 marginals on each side of midline strongly pointed; marginals 12/12, pleurals 4/4, and vertebrals 5 with little variation; hingeless plastron short (72- 76% of CL) and narrow-combination of the small plastron and the two narrow bridges form a cross; plastral bridges connected to carapace by a ligament, not fused as in other turtles.

Coloration and Pattern: Carapace brown; plastron and bridge cream to light brown with varying amounts of black pigment encrusted on surface; skin color of head, neck, and limbs dark brown but may be black in some populations. The head is very large with a blunt snout that protrudes slightly and a strongly hooked upper jaw. The muscular neck is long, about one-half to three-quarters of the CL. The limbs are muscular, with long claws and webbing between the toes. The tail is very long, about as long as the carapace, with a series of tubercles on the upper surface.

Sexual Dimorphism: Adult males are larger than females throughout the range of this species (Gibbons and Lovich, 1990). In Virginia, males averaged 271.9 ± 57.3 mm CL (190-415, n = 70), 202.3 ± 38.5 mm PL (145-300, n = 76), and 5.7 ± 3.6 kg body mass (1.53-16.0, n = 63). Females averaged 247.8 ± 32.6 mm CL (195-337, n = 47), 187.2 ± 23.8 mm PL (155-248, n = 50), and 3.8 ± 1.7 kg body mass (1.71-8.5, n = 40). Sexual dimorphism index was -0.10. The plastrons of some males are slightly concave. Precloacal distance varies with CL; females averaged 64.9 ± 13.2 mm (47-95, n = 11) and males averaged 106.4 ± 38.6 mm (52-165, n = 7). Males have larger heads than females.

Juveniles: Juveniles are similar to adults in morphology and color. The tubercles on the dorsum of the tail develop with age. The carapace, plastron, and skin of hatchlings are black upon emergence from the egg. White spots occur on the lateral marginals and along the margin of the plastron. Virginia hatchlings were 28.1-34.5 mm CL (ave. = 31.3 ± 1.9 mm, n = 106) and 18.2-23.1 mm PL (ave. = 20.9 ±1.1 mm), and weighed 6.7- 11.4 g (ave. = 9.2 ± 1.6 g).

Confusing Species: This species is usually not confused with other freshwater turtles in Virginia. Wood Turtles (Glyptemys insculpta) have long tails as juveniles but have a prominent middorsal keel and large plastron.

Geographic Variation: There is no discernable geographic variation in morphometries in Virginia populations. Snapping Turtles from blackwater cypress ponds and swamps have darker skins and shells than turtles from other aquatic systems. This is particularly true of the Snapping Turtles from Seashore State Park and swamps of the Blackwater River.

Biology: Snapping turtles occur in all manner of aquatic systems, including ponds, lakes, streams, rivers, swamps, and freshwater and brackish marshes. Areas providing aquatic vegetation and cover in the form of stumps, muskrat lodges and burrows, overhanging ledges, and/or soft, deep, organic substrate have the largest populations. Basking occurs only sporadically. The activity season extends from late March through October, but snapping turtles can be found in water in any month of the year. Over 99% of known Virginia records are April-September. Terrestrial activity occurs during the nesting season and in other warm months.

Snapping turtles are voracious predators. They will eat anything they can subdue. Foraging occurs during the day and night. The following prey have been recorded from Virginia specimens: crayfish, predaceous diving beetles, flies, catfish (Ictalurus spp.), toads (Anaxyrus spp.). Cope's Gray Treefrogs (Hyla chrysoscelis), Green Treefrogs (Hyla cinerea), muskrats (Ondatra zibethicus), aquatic macrophytes, duckweed (Lemna spp.), and filamentous algae. Adults and juveniles have been observed gulping algae and duckweed on the water's surface. Ernst and Barbour (1972) listed a wide range of amphibians, reptiles, mammals, and birds taken by this turtle. Adult snappers have few predators; humans are the primary ones. Raccoon (Procyon lotor) predation of adult snappers occurred in the ponds of Seashore State Park when winter water levels were low in the mid-1980s (J. C. Mitchell and C. A. Pague, unpublished). The raccoons apparently dug them out of the shallow mud and ate them from the rear while they were cold. Clark (1982) recorded a snapping turtle shell in a bald eagle (Haliaeetus leucocephalus) nest from Virginia. Juveniles are prey of large wading birds, large fish, and some snakes (Ernst and Barbour, 1972). Eggs in the nest are eaten by raccoons, skunks (Mephitis, Spilogale), and foxes (Urocyon, Vulpes). Knight and Loraine (1986) reported an egg of this species in the stomach of an Eastern Kingsnake (Lampropeltis getula) in South Carolina. Virginia snappers often carry leeches (Placobella spp.); most are attached to the skin but a few can be found on the shell.

In Virginia, Snapping Turtles lay a single clutch of 7-55 eggs (ave. = 27.0 ± 13.2, n = 13) in late May through mid-June. In Fairfax County, clutch size for this species varies from 12 to 34 (C. H. Ernst, pers. comm.). The smallest female known to be reproductively mature was 155 mm PL. Mating occurs in the spring and possibly in the fall. Copulation was witnessed in the Dismal Swamp by Schwab (1988d) on 30 March 1977 in which the male and female used both the plastron-to- plastron and the carapace-to-plastron positions; mating is forced copulation by the male. Nesting has been observed between 17 May and 29 June (Gotte, 1988; C. H. Ernst, pers. comm.). Nests, consisting of flask-shaped single cavities, are dug in a wide variety of soils. Most nesting in Michigan occurred 0800-1100 and 2000-2300 hours (Congdon et al., 1987). The eggs are spherical in shape, and in the present study averaged 26.3 ± 1.3 mm (23.4-27.6 mm, based on means of nine clutches) in diameter and 9.1-12.3 g body mass (ave. = 10.9 ± 1.0, based on means of seven clutches). Laboratory incubation period was 74- 81 days and hatchlings emerged 18-24 August. Ash (1951) reported 13-48 eggs in 85 females presumably from Virginia and an incubation time of 75-95 days. Hatchlings with umbilical scars or external yolk have been found in the field on 1, 24, and 30 August. Overwintering in the nest may occur in Fairfax County, as C. H. Ernst (pers. comm.) has found hatchling-sized individuals in late April and May.

The population ecology of snapping turtles is unknown in Virginia. Galbraith et al. (1987) found that males in a Canadian population were not territorial during summer but occupied overlapping home ranges; their spacing may have been due to aggressive interactions. Annual survivorship for adult females in Canada was estimated by those authors to be 96.6%. Because of their large size, the biomass of snapping turtles may exceed that of all other species in the freshwater turtle community. Biomass of two populations in South Carolina were 20.6-21.6 kg per hectare and of three populations in Michigan were 15.9-33.9 kg per hectare (Congdon et al., 1986).

The behavior of Snapping Turtles in and out of the water is drastically different. Snappers are very pugnacious on land, often striking out repeatedly at the collector while forcibly exhaling air from the lungs. The head is thrust outward and upward, oftentimes over the back of the shell. Although the neck is long, the striking distance over the shell is about one-half to two-thirds of the shell length. A full shell-length is a safe distance but a warm turtle will advance toward you. The bite is severe. Snappers are less defensive underwater. I have stepped on and bumped into snappers without their becoming defensive. Some turtle collectors find snappers by feeling for them under stumps and ledges with their hands. Large adult males are quite aggressive and will sometimes kill smaller males.

Remarks: Local common names for this species are "turtle" (Dunn, 1915a), mud turtle, and snapper. The largest snapping turtle reported in Virginia was one found in the Maury River near Buena Vista, Rockbridge County. It was a male measuring 415 mm CL and, based on a newspaper account (Buena Vista News, 6 September 1973), weighing 74 lb (33.6 kg). Only the shell remains, now in the American Museum of Natural History (AMNH 108817).

Snapping turtles are known to prey occasionally on ducks and geese in ponds. The effects of this predation are quite variable and depend on the local size of the turtle population and the extent to which they feed during the day. Since some foraging takes place at night, and the birds are on land during this period, the actual number of birds killed may be less than generally thought. Alexander (1943) examined the stomach contents of 470 snapping turtles in a Connecticut marsh and found that birds comprised less than 1% of the prey taken. However, Coulter (1957) reported losses of 10-13% of waterfowl populations in Maine from snapping turtle predation. Pond owners often try to have the turtles removed, but removal of snapping turtles is only a temporary measure at best.

Conservation and Management: This species is a game animal in Virginia, and many snappers are harvested each year for the food market. The meat is said to consist of seven flavors and is quite good. Unfortunately, there are no data on the effects of harvesting and its impact on local populations. I have been told by turtle collectors that it is easy to deplete a complete population such that it is at least a decade before the pond or lake can be collected again. Many turtles are taken during the egg-laying season, and the removal of females before they have laid their eggs seriously hinders population rebound.

There is a growing literature on toxic chemicals stored in snapping turtle fat and tissues. Compounds include organochlorides, particularly PCBs; the DDT metabolite DDE; the insecticide Dieldrin; and the heavy metals chromium, copper, mercury, nickel, and zinc (Stone et al., 1980; Albers et al., 1986). Although there are no data on contaminants in Virginia turtles, one wonders if some harvested individuals are safe for human consumption. The effects of harvesting need to be evaluated so that populations of this species can be properly managed. Studies of harvest rates, geographic distribution of harvests, and effects of harvest on demographic structure and population dynamics need to be conducted to determine if catch and season limits are warranted. Snappers remain an apparently abundant turtle in Virginia, but the growing demand for it as food poses an unknown threat to this potentially sustainable resource.

References for Life History

Photos:

*Click on a thumbnail for a larger version.



JD Kleopfer of the VA-DGIF holds all that remains of a Virginia record Eastern Snapping Turtle (Chelydra serpentina). This specimen was caught at Ft. Pickett in August 2008 by a commercial snapping turtle fisherman. The turtle weighed in at 51 lbs. (23.13 kg) with a straight-line carapace length of 18 1/3 in. (46.5 cm). The previous Virginia record was 35 lbs. (16.0 kg) with a straight-line carapace length of 16.3 in. (41.5 cm).


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