Green sea turtles are the only sea turtles that are herbivorous in adulthood. Young green sea turtles are mainly carnivorous and eat invertebrates such as sponges, jellyfish and crabs. However, they gradually shift to an entirely vegetarian diet as they exit their juvenile stage. The jaws of green sea turtles are finely serrated, an adaptation fit for their diet of sea grasses and algae.
Sea turtles can also live on carnivorous and omnivorous diets. Hawksbill sea turtles are carnivorous and eat mainly sponges, tunicates, shrimp and squid. They have a narrow head fit for getting food out of small crevices. Loggerhead and Ridley sea turtles are omnivorous and have jaws built for crushing food. Their diet consists of crabs, mollusks, shrimp, jellyfish and vegetation. Leatherback sea turtles have a fragile jaw and can only eat soft-bodied animals, such as jellyfish and tunicates.
Green sea turtles are one of the largest species of sea turtle. They can weigh up to 700 pounds and grow up to 5 feet long. They have a proportionally small head compared to most other species of sea turtle, and they cannot retract it into their shell. With an average lifespan in excess of 80 years, green sea turtles have one of the longest lifespans among sea turtles.