Since turtles are too slow to catch most prey by all-out pursuit, questions about what turtles eat are quite common. The answer is that turtle eating habits are varied—what they eat depends on the available food sources, the habitat in which the turtle lives and the turtle's behavior.
Most adult land turtles are plant eaters, also known as herbivores. They graze on grass or browse on the leaves of bushes and shrubs within their reach. Some turtles also eat fruits. On occasion, small insects such as caterpillars get caught-up in the plants turtles eat, and consequently turtles consume some invertebrates in this manner.
One group of turtles well-known for their herbivorous feeding habits are Galapagos tortoises. Galapagos tortoises feed on leaves and grasses and their diet is so influential that over the course of their evolution their shells have been modified in different ways to reflect their eating habits. Galapagos tortoise subspecies that eat grasses that lie close to the ground have shells that are dome-shaped with the rim of their shell lying snugly above their neck. Galapagos tortoise subspecies that eat leaves that are above the ground on bushes and shrubs have shells that are saddle-backed in shape, with the rim of the shell arched upwards enabling them to crane their neck high in the air as they grasp their food.
Freshwater turtles such as snapping turtles are ambush predators. Too cumbersome to swim after their prey with any great speed, snapping turtles instead tuck themselves into a bunch of aquatic vegetation and snap at anything that comes within their path. Consequently, snapping turtles eat fish and crustaceans.
Most freshwater turtles, when young, eat the larvae of aquatic invertebrates. As they grow older, their diet switches to aquatic vegetation.
Sea turtles eat on a variety of marine invertebrates and vegetation. For example, leatherback sea turtles feed on jellyfish, loggerhead sea turtles eat bottom dwelling shellfish, green sea turtles eat seagrass and algae.