Common snapping turtle (Chelydra serpentina)
|Also known as:||North American snapping turtle, Snapping turtle|
|Size||Adult carapace length: 23 - 49 cm (2)|
Hatchling carapace length: 2.5 - 3 cm (3)
|Weight||up to 34 kg (4) (5)|
- The largest recorded common snapping turtle weighed 34 kg.
- Female snapping turtles may make considerable migrations to find a suitable nesting site, with the longest recorded round trip being a massive 16 km.
- The common snapping turtle’s extremely varied diet makes it a somewhat flatulent species.
- Although the common snapping turtle prefers shallow waters, it is capable of diving to depths of 2 or 3 m or more.
- Painted turtles are known to remove leeches and algae from the shells of common snapping turtles.
The common snapping turtle is classified as Least Concern (LC) on the IUCN Red List (1).
A large, heavy-bodied reptile (2), the common snapping turtle (Chelydra serpentina) has a well-earned reputation for being somewhat short-tempered and highly aggressive (3).
This pugnacious reptile has a brown or olive to black upper shell, or carapace (3) (6), which is often obscured by mud or algae (2) (5). The carapace of the common snapping turtle has three rows of prominent ridges, known as keels, running along it (2) (3) (5) (6), although these tend to smooth over and be absent in older individuals (2) (5) (6). The back section of the shell is sharply serrated (2) (4) (5) (6). The lower shell, or plastron, of the common snapping turtle is relatively small (2) (3) (4) (6), cross-shaped (3) (4) (5) (6) and generally yellowish to tan in colour (5) (6).
The common snapping turtle has a large head with a pointed snout and a somewhat hooked upper jaw (2) (4) (5) (6). The skin on the upperparts of this species is generally grey to black or olive (5) (6), blending to lighter shades or dull yellow underneath (5). The head is often dark brown (4), while the powerful jaws are yellow to cream (6) and frequently sport a pattern of dark streaks (5) (6). Two barbels can be seen on the chin of the common snapping turtle (4) (5) (6), while the long neck is covered in warty projections called tubercles (3) (5) (6) (7).
The limbs of the common snapping turtle are large, powerful (3) (6) and heavily clawed (3) (5) (6), and the toes are webbed (4) (5) (6). This species has a long tail, which is about the same length as or longer than the carapace (2) (4) (6) and is adorned with a row of large, saw-tooth scales along the top (2) (5).
Male and female common snapping turtles are very similar in appearance, and so are difficult to tell apart based on external characteristics (5). However, males tend to have a more concave plastron (4) and are generally bigger than females (3) (4) (5) (6). Hatchling common snapping turtles have an almost round carapace (3) (6), and are either black or dark brown, often with white spots under the edge of the carapace or on the plastron (5). This white patterning disappears as the turtle gets older (3). Young common snapping turtles hatch with an ‘egg tooth’, a point on the end of the snout which is used to break through the eggshell when hatching. This is usually shed within the first three weeks (6).
The common snapping turtle occurs from southern Canada (2) (3) (7), southwards through the eastern two thirds of the United States (2) (3) (7). The range of this species stretches as far south as Florida (1) (6), New Mexico, the Gulf Coast (5) (6), and Central and South America (5) (7).
Different subspecies of the common snapping turtle are found in the southern regions, ranging into portions of Mexico (5) (7), Central America and north-western South America (5) (7). The Florida snapping turtle (Chelydra serpentina osceola) is restricted to peninsular Florida (6).
The common snapping turtle has been introduced to California (1) (2) (6), as well as to Japan and to China and Taiwan (1) (6), where it is being bred on turtle farms (6). Feral turtles of this species have also been recorded in the Netherlands and the United Kingdom (1).
The common snapping turtle is found from sea level up to elevations of 2,000 metres (1) (6).
The common snapping turtle inhabits a wide range of water bodies (1) (6), from rivers and lakes to temporary ponds and marshes (1). However, this species tends to show a preference for slow-moving waterways which have a sandy or soft mud bottom (3) (5) (6) and an abundance of aquatic vegetation (2) (3) (5) (6). The water bodies inhabited by the common snapping turtle are usually shallow, but this reptile can also be found along the edges of deep lakes and rivers (6).
Beaver lodges and muskrat bank burrows are an important component of common snapping turtle habitats, as this large reptile often uses such cavities for shelter. The Florida snapping turtle (C. s. osceola), a subspecies of the common snapping turtle, lives up to its fearless reputation by occasionally sharing shelter holes with alligators (Alligator mississippiensis) (6).
Although considered to be a freshwater species, the common snapping turtle can sometimes be found in brackish coastal waterways (6), including tidal creeks (1). Surprisingly, the common snapping turtle is relatively tolerant of polluted waters (5), and is one of relatively few reptiles which can regularly be found in acidic streams (6).
Juvenile common snapping turtles usually occur in shallower, vegetated habitats, shifting to deeper water as they grow. This may be linked to a preference for taking larger prey as an adult (6).
One of North America’s most aquatic turtles (2), the common snapping turtle spends much of its time lying on the bottom of a water body or buried in mud in shallow water (2) (3) (5) (6). Although this species is seldom seen basking (2) (5), by day the common snapping turtle can often be seen floating lazily just below the water’s surface (2) (5) (6). Despite being a capable swimmer, the common snapping turtle tends to move by walking along the bottom of a pond or other water body (5).
The common snapping turtle is an omnivorous reptile (2) (6), and eats almost anything it can fit into its sharp jaws (6). Its extremely varied diet includes a wide selection of invertebrates such as worms, leeches, bivalves, snails, shrimp, crayfish and crabs (6) (7). Insects, including beetles and butterflies, are also frequently taken (6), as are fish, amphibians, other small turtles, snakes, small mammals and even birds (3) (6). This bold reptile has even been reported to steal fish from fishermen’s lines (6). The common snapping turtle also eats algae and plant material (1) (3) (5) (6), and is known to scavenge on carrion (1) (2) (5) (6). Hatchling common snapping turtles generally feed on worms, fish and tadpoles (7).
While young common snapping turtles actively forage for food, adults tend to employ a sit-and-wait strategy, ambushing prey as it swims past (5). Prey may be stalked slowly, and the common snapping turtle claims its prize with a rapid extension of its head and neck (5) and a strong bite which is capable of tearing flesh (6).
Most common snapping turtles enter hibernation by late October (6), overwintering at the bottom of permanent, generally shallow waters, buried under the mud or hiding beneath debris (2). Hibernation usually ends around April, but this varies depending on the location. In the summer, some common snapping turtles may aestivate if waterways have dried up, although others simply migrate to wetter areas (6).
The male common snapping turtle matures at a carapace length of around 18 to 19 centimetres, and the female at around 20 to 22 centimetres (6). Over most of its range, the common snapping turtle mates from late March to November, although in southern Florida this species may mate throughout the year (6). Some courtship behaviour has been described, but this tends to vary between populations. To mate, the male common snapping turtle mounts the female (2) (5) (6), gripping hard with its feet. The male may bite the female on the head and neck, and places its chin over the female’s snout (5) (6).
Over much of North America, the main nesting period of this species is between mid-May and mid-June, although this can be earlier in the south and later in the north (6). Using its hind feet (6), the female common snapping turtle digs a flask-shaped nest (2) (5), usually in relatively loose sand, vegetable debris, or even sawdust at old mills (6). In most populations of the common snapping turtle, only one clutch is laid per breeding season (2) (6) (7), although in Florida, C. s. osceola may lay two to four clutches per year. Once a clutch has been laid, the female covers up the nest (6).
The white, spherical eggs of the common snapping turtle have a tough, leathery shell (2) (6), and are roughly the size of a ping-pong ball (7). A clutch consists of between 25 and 45 eggs (6), which are usually incubated for 75 to 95 days (1) (6). The sex of the common snapping turtle hatchlings is determined by the temperature at which the eggs were incubated (2) (3) (6) (8), with warmer incubation temperatures producing female turtles, and cooler temperatures producing males (6).
Despite suffering local declines in some areas, the common snapping turtle is not considered to be a threatened species, as it is relatively widespread and adaptable. However, overexploitation, habitat loss and degradation are among the factors responsible for declines in certain populations (1).
One of the main threats to the common snapping turtle is nest predation (2) (5) (6). A wide variety of species, including skunks and raccoons, excavate and destroy nests as they forage for eggs (6), with nest losses in some areas typically ranging from 60 to 100 percent (5). Hatchlings and small common snapping turtles often fall prey to bullfrogs, large fish, herons, alligators and coyotes. The common snapping turtle is also consumed by humans throughout its range (6).
Some PCBs, pesticides and other pollutants have been shown to increase abnormalities in hatchling common snapping turtles (9). However, adults appear to be less affected by these chemicals, despite accumulating them in their bodies (1). This makes the common snapping turtle an ideal species for monitoring pollutant levels in aquatic environments (1) (6).
Common snapping turtles also drown in fishing nets (6) and are frequently hit by cars (1) (6). Female common snapping turtles are especially vulnerable to being killed on roads, particularly during the nesting season when they may travel considerable distances to locate a satisfactory nesting site. The drainage of water bodies may also be a threat to the common snapping turtle by reducing suitable habitat (6).
Although the common snapping turtle is not considered to be a threatened species, it is widely exploited, and significant population declines have been recorded in the northern limits of its range (1).
Leeches frequently parasitise the common snapping turtle (5) (6), which can lead to considerable blood loss if there is a heavy burden of parasites (6).
Canada and many U.S. states have attempted to manage the exploitation and trade of the common snapping turtle by placing it under varying degrees of regulation or legislation. For instance, capture of the common snapping turtle from the wild is prohibited in Michigan, New York and several other states. However, in other areas, including Alabama, Maryland and Texas, wild capture of this species is unregulated (1).
In the U.S., trade in the common snapping turtle is restricted to individuals with a carapace length of over 10 centimetres, with smaller individuals only being available for educational purposes (1).
The common snapping turtle is found in many protected areas, both public and private (1).
More information on the conservation of turtles:
Turtle Conservation Fund:
IUCN/SSC Tortoise and Freshwater Turtle Specialist Group:
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- Aestivate: to become dormant during the summer or dry season, comparable to hibernation in winter.
- Algae: simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
- Barbels: fleshy projections near the mouth of some aquatic vertebrates.
- Bivalve: a group of aquatic molluscs in which the soft parts are encased in a shell consisting of two parts, known as valves.
- Brackish: slightly salty water, usually a mixture of salt and freshwater, such as that found in estuaries.
- Carapace: the top shell of a turtle or tortoise. In arthropods (insects, crabs etc), the fused head and thorax (the part of the body located near the head), also known as the ‘cephalothorax’.
- Carrion: the flesh of a dead animal.
- Feral: previously domesticated animals that have returned to a wild state.
- Hibernation: a winter survival strategy in which the animal passes the winter in a resting state. This period of inactivity is characterised by specific biological and biochemical changes including lowered blood pressure and respiration rate. In reptiles, this is also known as brumation.
- Incubate: to keep eggs warm so that development is possible.
- Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
- Keel: a projecting ridge along a flat or curved surface, particularly down the middle.
- Omnivorous: feeding on both plants and animals.
- Parasite: an organism that derives its food from, and lives in or on, another living organism at the host’s expense.
- Parasitism: interaction in which one organism derives its food from, and lives in or on, another living organism (the host) at the host's expense.
- Plastron: the lower shell of a turtle or tortoise.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
- Tubercle: a small, rounded, wart-like bump on the skin or on a bone.
IUCN Red List (July, 2012)
- Degenhardt, W.G., Painter, C.W. and Price, A.H. (2005) Amphibians and Reptiles of New Mexico. University of New Mexico Press, Albuquerque, New Mexico.
- Russell, A.P., Bauer, A.M., Lynch, W. and McKinnon, I. (2000) The Amphibians and Reptiles of Alberta: A Field Guide and Primer of Boreal Herpetology. University of Calgary Press, Calgary, Alberta.
- Savage, J.M. (2002) The Amphibians and Reptiles of Costa Rica: A Herpetofauna Between Two Continents, Between Two Seas. University of Chicago Press, Chicago.
- Harding, J.H. (1997) Amphibians and Reptiles of the Great Lakes Region. University of Michigan Press, Michigan.
- Ernst, C.H. and Lovich, J.E. (2009) Turtles of the United States and Canada. The Johns Hopkins University Press, Baltimore, Maryland.
- Bartlett, R.D. and Bartlett, P.P. (2006) Turtles and Tortoises. Barron’s Educational Series, New York.
- Yntema, C.L. (1976) Effects of incubation temperatures on sexual differentiation in the turtle, Chelydra serpentina. Journal of Morphology, 150(2): 453-461.
- Bishop, C.A., Ng, P., Petit, K.E., Kennedy, S.W., Stegeman, J.J., Norstrom, R.J. and Brooks, R.J. (1998) Environmental contamination and developmental abnormalities in eggs and hatchlings of the common snapping turtle (Chelydra serpentina serpentina) from the Great Lakes-St Lawrence River basin (1989-91). Environmental Pollution, 101:143-156.