• Snapping turtles are common across North America and are often among the largest turtles found in any given region. Their several distinctive characteristics include shells that appear too small for their bodies, leaving their head and joints to protrude more than other types of turtles, powerful jaws, long necks and some sort of spiny structure on the shell, legs or tail. These spines contribute to a prehistoric appearance that often earns them a comparison to dinosaurs.
  
  

Alligator Snapping Turtle

• Alligator snapping turtles have rows of spiny ridges along their shells that look like alligator skin and give these snappers their name. The spiky skin on their necks, tails and limbs contributes to an overall threatening appearance, which is enhanced by their size. Male alligator snappers have been known to exceed 220 pounds, making them easily the largest freshwater turtle in North America, according to National Geographic. Alligator turtles can live up to 70 years, and they have no known predators but humans. Yet they are considered a threatened species because of habitat encroachment and unregulated harvesting for their meat and exotic-looking shells. There are no subspecies of alligator snapping turtles, which are found exclusively in the southeastern United States.
  
  

Florida Snapping Turtle

• With soft, pointed spikes on the head and neck and three saw-toothed ridges running down its tail, the Florida snapping turtle (Chelydra serpentina osceola) is the spiniest of the four subspecies of common snapping turtles. These snappers are found exclusively in Florida. They spend most of their time at the muddy bottoms of ponds and lakes with lots of vegetation. Like other common snapping turtles, Florida snappers reach a maximum size of 18 inches and 35 pounds and are aggressive predators. They will try to bite if they are approached on land, according to Marianne Cowley, publisher of Your Florida Backyard.
  
  

Mexican Snapping Turtle

• Mexican snappers (Chelydra serpentina rossignoni) are similar in appearance to their Florida cousins, with the same pattern of spiky growths on their heads and necks. They has three ridges along its shell that get smaller as the turtles age. They also have four to six fleshy growths called barbels on their chins. The Mexican snapper is found in the slow-moving fresh waters of Mexico and upper regions of Honduras, Belize and Guatemala.
  
  

Ecuadorian Snapping Turtle

• Ecuadorian snapping turtles (Chelydra serpentina acutirostris) have wart-like projections on their necks and other parts of their bodies that are somewhat spiny, but not as sharp as those found on the Florida and Mexican turtles. Their shells are also flatter than the other subspecies of common snapping turtles, making them the least spiky turtles in this group. Ecuadorian snappers are found in northern Honduras, eastern Nicaragua, Costa Rica, Panama, Pacific Colombia, Ecuador and the Gulf of Guayaquil.
  
  

Northern Common Snapping Turtle

• The northern common snapping turtle (Chelydra serpentina serpentina) is the most common and abundant of the common snapping turtles and is found throughout southern and eastern Canada and the eastern United States. These turtles have the same warty spikes on the neck and other parts of the body as other types of common snappers, but like those on Ecuadorian snapping turtles, they are rounder than those on the other two subspecies. They also have three spiky ridges on their shells that decline with age.