What do sea turtles eat?

By Aubry Forsyth

People often think that all sea turtles eat only one thing – jellyfish. However, their diets are much more diverse and depend on the species of sea turtle. This diversity is one way sea turtles play an important role in the health of ocean and coastal ecosystems. By consuming different species, sea turtles provide checks and balances in the food web.

As adults, flatback and olive ridley sea turtles are both omnivores, eating a variety of animals and plants. Meanwhile, green sea turtles as adults are herbivores, eating vegetation. Loggerhead and Kemp’s ridley sea turtles are carnivores, eating other animals. Leatherbacks are referred to as gelatinivores because their diet consists of gelatinous prey like jellyfish and sea squirts. Hawksbill sea turtles often are referred to as spongivores due to their specialized diet that consists almost entirely of sponges. Listed below are the most commonly consumed prey for each species of sea turtle:

• Green: algae, seagrasses, and seaweed
• Leatherback: jellies and other soft-bodied invertebrates like tunicates and sea squirts
• Loggerhead: crabs, conchs, whelks, and horseshoe crabs
• Hawksbill: almost exclusively sponges
• Olive ridley: crabs, shrimp, lobster, sea urchins, jellies, algae, and fish
• Kemp’s ridley: crabs, fish, jellies, shrimp, and mollusks
• Flatback: sea cucumbers, jellies, corals, shrimp, crabs, mollusks, fish, and seaweed

Sea turtles do not have teeth to help them eat; instead, they have keratinous beaks with varying structures to accommodate their diets. Green sea turtles have finely serrated beaks that enable them to scrape algae off rocks and tear grasses and seaweeds. Loggerhead sea turtles have large heads and incredibly strong jaws that allow them to crush hard-shelled prey. Hawksbill sea turtles have sharp, narrow beaks that enable them to reach inside crevices on a reef. Kemp’s ridley and olive ridley sea turtles both have well-adapted jaws for crushing and grinding, allowing them to eat hard-shelled organisms. Flatback sea turtles have slightly serrated jaws that allow them to eat a wide variety of marine organisms. Leatherbacks have delicate, scissor-like jaws, with two sharp cusps on both parts of their jaw that allow them to pierce soft-bodied organisms, like jellyfish. Leatherbacks, along with a few other species, have an interesting — and slightly terrifying — adaptation called papillae that line the inside of the esophagus. These backward-pointing spines make it certain that once a jellyfish is caught in the turtle’s jaws, it will not be able to escape.

Unfortunately, sea turtles don’t always eat what they should. For leatherback sea turtles in particular, plastic waste is incredibly dangerous. When floating in the water, plastic debris looks extremely similar to jellyfish, and leatherbacks often eat plastic by mistake. Luckily, you can help stop the plastic problem by making choices such as using reusable products as often as you can, buying in bulk, and recycling what you are able. 

For more information regarding sea turtles’ diets, visit: https://www.seeturtles.org/sea-turtle-diet/