The turtle's shell is very sharply serrated in the rear. There are three blunt, broken keels, rising as tubercles at the rear margins of the shields through which they pass. The shell of old individuals is quite smooth whilst young turtles are exceedingly rough. The plastron (underneath) is small and narrow, exposing a great amount of the turtle's fleshy parts. The under-surface of the tail is covered with large shields. As with all of the very aquatic turtles, the feet are broad and extensively webbed with very large nails!

The snapping turtle's appearance includes a carapace in dull olive or dark brown, with little or no markings, and a dull yellow plastron. The upper portion of the head is very dark as is the upper surface of the legs and tail which are yellowish underneath.

The turtle is carnivorous, and never feeds unless underwater. Snapping turtles will sometimes grab prey on the bank of a stream and then retreat to the water to eat.

Snapping turtles are almost unique among turtles, they can defend themselves by "striking" at enemies, almost snake like and at a speed which rivals that of a rattlesnake strike, almost too quick for the bare eye to follow. This, combined with the sharp-edged, cutting mandibles and jaw muscles of tremendous power, the strike can cause serious injury. A fully grown adult could easily bite off the finger, hand or toe of a human.