Head to head
Common Snapping Turtle vs Alligator Snapping Turtle
Both are large, powerful freshwater turtles of North America that cannot pull fully into their shells and defend themselves by biting. But they are different animals with different lives. The common snapping turtle is found across almost the whole eastern half of the continent and roams widely. The alligator snapping turtle is a bigger, rarer, southern species that sits still on the river bottom and lets its food come to it.
| Common Snapping Turtle | Alligator Snapping Turtle | |
|---|---|---|
| Scientific name | Chelydra serpentina | Macrochelys temminckii |
| Typical weight | 4 to 16 kg | 20 to 90 kg |
| Shell | Rounded, three low keels, smooth in adults | Three rows of tall jagged ridges; extra edge scutes |
| Head | Large, but proportionate | Massive, with a sharply hooked beak |
| Hunting style | Active forager and opportunist | Sit-and-wait ambush, using a worm-like lure on the tongue |
| Range | Most of eastern and central North America | Gulf coast and lower Mississippi drainages only |
| Lifespan | Commonly 30 to 50 years | Often 80 to 100 years or more |
| Conservation status | Least Concern | Vulnerable |
Snapping Turtle vs Alligator Snapping Turtle: common questions
How do I tell the two snapping turtles apart?
Look at the shell and the head. An alligator snapping turtle has three prominent rows of large, pointed, ridged scutes running down its back, giving it a rough, mountainous, dinosaur-like profile, plus a huge head with a hooked, beak-like upper jaw and an extra row of small scutes between the main shell edge and the large marginal scutes. A common snapping turtle has a much smoother, lower, more rounded shell, with only three low keels that flatten out as the animal ages, and a large but less monstrous head. Size helps too: an adult alligator snapper is usually far heavier than a common snapper, though young ones overlap.
Does the alligator snapping turtle really fish with a lure on its tongue?
Yes. It has a small, thin, pink projection on the floor of its mouth that closely resembles a wriggling worm or grub. The turtle settles on the river bottom, opens its jaws wide, stays completely still, often for many minutes, and twitches the lure. A fish that comes in to investigate is snapped up when the jaws close, which they do fast enough that the strike is hard to see. This tongue-luring is unusual among turtles and is one reason the alligator snapper can be so sedentary; it does not need to chase prey.
Are snapping turtles dangerous to swimmers?
Much less than their reputation suggests. In the water, both species are wary and will swim away from a person rather than confront one; almost all serious bites happen on land or when someone picks the turtle up, steps on it, or reaches into its space, often while fishing or trying to move it off a road. On land a common snapping turtle in particular will stand tall, hiss, and lunge, and both species can bite hard enough to cause a deep wound, so they should be given room. The old claim that a snapping turtle can take off a finger or a toe is exaggerated for the ordinary common snapper but a large alligator snapper has a genuinely formidable bite.