Snapping turtles receive their name from the snapping motion they make with their mouths. These turtles are usually too large to retreat into their shells, so snapping is the primary line of defense. Snapping turtles have sharp, beak-like mouths that enable them to eat meat and vegetation. Some snapping turtle dietary items are invertebrates, fish, small birds, amphibians and aquatic vegetation.
Sea turtles are marine-dwelling species found in most of the world's oceans. These turtles have flippers, which helps them swim efficiently; however, this makes sea turtles awkward on land. Sea turtles are not able to retract their heads into their shells. Some sea turtles are carnivorous (loggerheads, leatherbacks and Ridley's), while the green and black sea turtles are herbivorous. The carnivorous sea turtles have powerful jaws and herbivorous sea turtles have serrated teeth for grinding vegetation.
One of the largest turtle species in the world are tortoises. Tortoises differ from other turtle species since they spend most of their lives on land, while most turtles primarily live in water. These reptiles do not have webbed feet, but are usually much bulkier than turtles. Tortoises also dig burrows to escape extreme temperatures. Tortoise are omnivores and eat insects, amphibians and vegetation. Like most turtles, tortoises do not have teeth, but rely on their mouths, which have sharp edges.
Soft-shelled turtles are completely aquatic creatures and make their homes in bodies of water with sandy or muddy bottoms. These reptiles have soft shells, which help them swim faster. Soft-shelled turtles also have sharp-edged mouths and are carnivorous. Insects, crustaceans and fish are part of the soft-shelled turtle's diet. Soft-shelled turtles are also territorial and aggressive when threatened.
Pond turtles spend most of their time in water in the summer, but retreat to land for laying eggs or finding warm shelters during the winter. These turtles are omnivorous and dine on insect, insect larvae, crayfish, frogs, vegetation, fish and algae. One pond turtle species, the western pond turtle, swallows its food while underwater. Throughout most of the year, pond turtles are diurnal -- active during the day -- but have nocturnal habits in the summer.