The green sea turtle’s food chain is short and simple: seagrass and algae are eaten by adult green turtles, and turtles are eaten by large sharks (and, historically, by people). Young turtles eat a broader mix that includes small animals. Here is the full picture, in plain language.
Green Sea Turtle Food Chain at a Glance
Seagrass and algae → green sea turtle → large shark (such as a tiger shark) → decomposers return nutrients to the sea.
For hatchlings: plankton, small crustaceans, jellyfish → young green turtle → seabirds, crabs, fish, and other predators.
What Do Green Sea Turtles Eat?
- Adults are herbivores. According to NOAA, they feed mainly on seagrasses and algae, grazing on the seafloor in shallow coastal waters.
- Hatchlings and juveniles spend their first years in the open ocean and eat a more varied diet. This can include jellyfish and other small invertebrates, plus algae, before they shift toward plants as they settle in coastal feeding areas.
Their green color, which gives the species its name, comes from the fat beneath their shell, which is tinted by their plant-based diet.
What Eats Green Sea Turtles?
- Eggs: ghost crabs, raccoons, foxes, dogs, monitor lizards, and birds, depending on the beach.
- Hatchlings: seabirds, crabs, and fish as they race to the water.
- Adults: few natural predators. Large sharks, especially tiger sharks, are the main threat, along with orcas in some areas.
- People: historic harvesting of eggs and adults caused sharp declines worldwide, and incidental capture in fishing gear remains a problem.
Why the Food Chain Matters
Green turtles graze on seagrass the way cattle graze a pasture. Trimming the blades helps beds stay healthy and productive, and seagrass meadows shelter many fish and invertebrates. Turtle eggs also move nutrients from the ocean to beach dunes. If turtle numbers fall, seagrass beds and the animals that depend on them can change.
Food Webs for Other Sea Turtles
Other species eat very differently. The loggerhead, for example, mainly eats crabs and other hard-shelled animals. See our loggerhead sea turtle food web to compare. If you keep a freshwater turtle at home, our guide to what plants turtles eat covers plant foods for pets.
Bottom Line
Adult green sea turtles eat seagrass and algae, young turtles eat a wider mix, and sharks are their main natural predator. Protecting seagrass beds and nesting beaches is the best way to protect this food chain.
