The common snapping turtle, has a jaw that closes with enough force to sever a human finger cleanly and, in documented cases, to snap a wooden broomstick in half. The bite is not the fastest or the most powerful in the animal kingdom in absolute terms, but relative to body size and the speed of delivery, it is among the most dangerous of any freshwater animal in North America.
The neck is the other feature worth knowing about. A snapping turtle can extend its neck to reach almost any point on its own shell, which is why picking one up from behind, the instinctive approach, is not as safe as it appears. The reach is longer than most people expect, and the speed of the strike is faster than most people can react to.
Snapping turtles are not aggressive in water, where they can simply swim away from threats. The aggression is a terrestrial defense, deployed when the turtle is out of water and cannot retreat. A snapping turtle encountered on land is a snapping turtle that has no other options, and it responds accordingly.
The fossil record shows snapping turtles in forms essentially identical to modern species dating back to the Cretaceous period, approximately 90 million years ago. They shared their wetlands with dinosaurs and have outlasted them by a considerable margin. The body plan, a large flat shell, a powerful jaw, a long extensible neck, and a bad temper on land, has proven durable across an extraordinary range of environmental conditions.
Snapping turtles are omnivores and scavengers, eating fish, frogs, aquatic invertebrates, waterfowl, small mammals, and a significant quantity of aquatic vegetation. They are important nutrient cyclers in freshwater ecosystems, processing carcasses and organic material that would otherwise accumulate on the bottom. In some wetland systems they are the dominant large predator, shaping the community composition of fish and amphibian populations through their feeding activity.
Females travel overland to lay eggs, sometimes covering several kilometers to reach suitable nesting sites, and this terrestrial movement brings them into contact with roads. Road mortality is a significant source of adult snapping turtle mortality across their range, and because snapping turtles do not reach sexual maturity until 15 to 20 years of age, the loss of adult females to road strikes has population-level consequences that take decades to become apparent.
The Nest
A female snapping turtle digs a flask-shaped nest in sandy or loamy soil, deposits 20 to 40 eggs, covers them, and leaves. She provides no further parental care. The eggs incubate for 9 to 18 weeks depending on temperature, and the sex of the hatchlings is determined by incubation temperature rather than genetics, with warmer temperatures producing females and cooler temperatures producing males. Climate warming is shifting the sex ratios of snapping turtle populations in ways that are being monitored but whose long-term population consequences are not yet fully understood.
The hatchlings that emerge are approximately the size of a quarter and face predation from raccoons, herons, large fish, and other turtles. Those that survive to adulthood face very little predation. A large adult snapping turtle has essentially no natural predators. It has been that way, more or less, since the Cretaceous.
