Adults of most species inhabit shallow coastal waters. Some species migrate great distances form winter feeding grounds to summer nesting areas. Sea turtles are strong swimmers and divers. Green sea turtles can stay under water as long as five hours. To conserve oxygen, their hearts can slow to one beat every nine minutes.
Diets vary greatly among sea turtle species.
Green and black sea turtles feed on seagrasses and algae. Loggerheads' and ridleys' strong jaws can crush crabs, shrimps, and molluscs. Leatherbacks prey only on jellyfish and other soft-bodied animals. In general, sea turtles do not come out onto land, except females when they nest. Most nest during the warmest months, returning to the same beaches year after year.