Updated Octoboer 2026
Sea turtles don’t have teeth. Instead, they use hard, beak-like jaws to bite and tear their food. What they eat depends on the species, and the Hawaiian green sea turtle, known locally as honu, has a diet that changes as it grows.
If you’ve spotted a turtle while snorkeling in Hawaii, you might have noticed its small, pointed face and wondered how it eats without teeth. The answer has a lot to do with the turtle’s diet and the role it plays in Hawaii’s coastal ecosystem.
How Do Sea Turtles Eat Without Teeth?
Sea turtles have beaks made of a tough material called keratin, the same protein found in human fingernails. Unlike teeth, their beaks don’t need to be replaced individually. Each species has a jaw shape suited to the food it eats.
Some sea turtles have strong, broad jaws for crushing hard-shelled prey. Others have narrow, pointed beaks that help them reach food hidden in small spaces.
Green sea turtles have serrated edges along their jaws, which help them bite through marine vegetation. Their mouths aren’t designed for chewing the way ours are. Instead, they grip and tear food into manageable pieces before swallowing.
It’s a useful adaptation for an animal whose diet consists largely of plants.
What Do Hawaiian Green Sea Turtles Eat?
Hawaiian green sea turtles, or honu, eat primarily algae and other marine vegetation as adults.
Despite their name, green sea turtles aren’t green because of their shells. Their name comes from the greenish color of the fat beneath their shells, which is associated with their plant-based diet.
Their main food sources include:
- Marine algae: Green sea turtles graze on algae growing on rocks and other underwater surfaces.
- Seagrass: In areas where seagrass beds are available, it can be an important part of their diet.
- Other marine plants: Their diet varies depending on the habitat and the food available.
Young green sea turtles have a more varied diet than adults. Juveniles may eat animal matter as well as plant material before their diet shifts toward vegetation as they mature.
In Hawaii, algae is particularly important to the diet of adult honu.
If you see a green sea turtle grazing underwater, it may be feeding on algae along a reef. They can also spend time resting on the ocean floor or swimming between feeding areas.
Do All Sea Turtles Eat the Same Food?
Not at all. There are seven living species of sea turtles, and their diets differ considerably.
Green sea turtles
Adult green sea turtles eat mainly algae and seagrasses. Their serrated jaws help them crop vegetation from underwater surfaces. They are the species you’re most likely to hear about when learning about honu in Hawaii.
Hawksbill sea turtles
Hawksbills have a narrow, pointed beak that helps them reach into reef crevices. Sponges make up a large part of their diet, although they eat other invertebrates, too. Their feeding habits are closely associated with coral reef habitats.
Loggerhead sea turtles
Loggerheads have large heads and powerful jaws for crushing hard-shelled prey. They eat animals such as crabs, mollusks and other marine invertebrates.
Leatherback sea turtles
Leatherbacks primarily eat jellyfish and other soft-bodied animals. Rather than having the hard, crushing jaws associated with some other species, they have delicate jaw structures and backward-pointing projections in their mouths and throats that help them swallow slippery prey.
The differences make sense when you consider how specialized each species is. A jaw that works well for grazing on algae wouldn’t be nearly as useful for crushing a crab or catching a jellyfish.
Why Are Green Sea Turtles Important to Hawaii’s Marine Ecosystem?
Green sea turtles are part of a much larger coastal ecosystem.
By feeding on algae and seagrasses, they influence how vegetation grows in the areas where they feed. Their grazing can help shape these habitats, although the effects depend on the location and the balance of other marine life.
Honu are also an important part of Hawaii’s natural and cultural heritage. The Hawaiian word honu refers to the green sea turtle, an animal that holds a special place in Hawaiian culture.
Hawaiian green sea turtles were heavily affected by human activity in the past. Conservation measures and legal protections have helped the population recover, although the turtles still face threats from habitat degradation, fishing gear, boat strikes and other human activities.
Green sea turtles are protected under the U.S. Endangered Species Act. In Hawaii, it’s illegal to harass, harm or pursue them. If you encounter one while swimming or snorkeling, give it plenty of space and never touch or chase it.
Where Can You See Sea Turtles in Oahu?
Oahu has several popular places to see Hawaiian green sea turtles, both from shore and in the water.
Turtle Canyon, near Waikiki
Turtle Canyon is a well-known snorkeling destination offshore from Waikiki. Green sea turtles are often seen in the area, making it a popular stop on guided boat tours. Because the turtles are wild, sightings are never guaranteed.
Oahu’s west coast
The Waianae Coast offers opportunities to see marine wildlife in a different setting from the busy beaches of Waikiki. Depending on the location and ocean conditions, snorkelers may encounter green sea turtles along with tropical fish and other marine life.
Shoreline viewing spots
Sea turtles sometimes come ashore to rest, particularly at locations where they regularly haul out. If you spot one on the beach, observe it from a respectful distance and avoid blocking its path back to the ocean.
A Few Tips for Snorkeling Around Honu
If seeing a sea turtle is on your Hawaii itinerary, remember that the encounter should happen on the turtle’s terms.
- Keep a respectful distance and follow your guide’s instructions.
- Never touch, feed or chase a turtle.
- Don’t block a turtle’s path to the surface. Sea turtles need to breathe air.
- Avoid standing on coral or disturbing marine life while snorkeling.
- Follow local guidance and applicable wildlife-protection rules.
You don’t need to get close to a turtle to appreciate it. Watching one glide over a reef or surface for air can be memorable all on its own.
See Hawaiian Green Sea Turtles on Your Oahu Trip
If you’d like to see honu in their natural environment, a guided snorkeling tour is one way to explore Oahu’s underwater world.
Turtles & You takes guests to Turtle Canyon, a popular snorkeling area near Waikiki where Hawaiian green sea turtles are frequently spotted. The tour gives visitors an opportunity to explore the water with a crew familiar with the area.
As with any wildlife experience, sightings depend on natural conditions. The turtles aren’t trained or brought in for guests, and they should always be observed without touching or chasing them.
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