Snapping turtles mature slower and larger in the north
Chelydra serpentina, a hefty freshwater chelydrid of eastern North America, is famously pugnacious on land with beaklike jaws and a long neck strike. Northern females may not mature until ages fifteen to twenty, later and larger than southern peers.
The common snapper, Chelydra serpentina, is a large freshwater turtle whose natural range runs from south-eastern Canada and Nova Scotia down to Florida and west to the edge of the Rockies. Its species name means snake-like, after the long, highly mobile neck that powers its strike. No subspecies are currently accepted: the old Florida form osceola is treated as the same species, while two former subspecies, Chelydra rossignonii and C. acutirostris, are now full species.
Adults usually weigh 4.5 to 16 kilograms with shells 25 to 47 centimetres long; males are the bigger sex and keep growing all their lives, and the heaviest wild one caught reportedly reached 34 kilograms. Northern females mature at 15 to 20 years versus about 12 in the south, and mark-recapture work in Algonquin Park suggests some live beyond 100. They are omnivorous scavengers and ambush hunters of fish, frogs, snakes, birds and small mammals, helped by a keen sense of smell. Crows, mink, skunks, foxes and raccoons dig up the eggs, finding nests by sight, soft soil and the female's musk.
Females can store sperm for several seasons and lay 25 to 80 eggs a year in sandy soil, and hatchlings click and creak before emerging. In the north, ice can stop them breathing air for more than six months; they slash their metabolism and absorb oxygen from the water, then switch to anaerobic metabolism if that falls short. Out of water they bite fiercely and can reach a handler holding the shell's sides, yet in water they usually slip away, and turtle-soup eaters face pollutants concentrated in the flesh.
Source: Common snapping turtle
