Honu Behavior: All About the Hawaiian Green Sea Turtle
What Do Hawaiian Green Sea Turtles Eat, Where Do They Sleep, and How Long Do They Live?
If you’ve spent time snorkeling in Hawaiʻi, you’ve probably seen a honu, the Hawaiian green sea turtle. They are one of the most commonly encountered sea turtles in Hawaiʻi and can often be spotted around shallow reefs, slowly swimming, feeding, or resting on the ocean floor.
But what is a honu actually doing when you see one underwater?
From what they eat to where they sleep, Hawaiian green sea turtles have some pretty interesting habits.
How Long Do Hawaiian Green Sea Turtles Live?
Hawaiian green sea turtles are long-lived animals. They are estimated to live 60-80 years or even longer! although determining the exact age of a wild turtle is difficult. They also grow slowly and don’t reach breeding age until they are roughly 25 to 35 years old. So the large honu you see around Oʻahu’s reefs may have been living in Hawaiian waters for decades.
What Do Honu Eat?
Adult honu are mostly herbivores. They spend much of their time grazing on limu, algae, and seagrasses around shallow reefs and rocky coastal areas. If you’ve ever watched a turtle slowly moving along the ocean floor, stopping every few feet, it may be feeding. Their grazing is also an important part of the reef ecosystem. Young honu have a more varied diet before transitioning to the mostly herbivorous diet of adults.
Where Do Honu Sleep?
Honu can rest underwater on the ocean floor, often finding sheltered areas such as reef ledges, crevices, or other protected spots. They can hold their breath for surprisingly long periods while resting. NOAA notes that resting adults can potentially remain underwater for up to three hours, although they typically surface much more frequently. Hawaiian green turtles also love basking, or resting on beaches. Hawaiʻi is one of the only few places in the world where green sea turtles regularly exhibit this behavior.
So if you see a honu lying quietly on the sand, it isn’t necessarily sick or stranded. It may simply be taking a much needed nap.
Why Do Honu Spend So Much Time Resting?
Honu aren’t constantly on the move. Much of their day can involve a combination of feeding, swimming, and resting. When you see one sitting quietly on the reef, it’s best to leave it alone. Approaching a resting turtle can cause it to abandon its resting spot and use valuable energy to move away. Giving honu space allows them to continue their natural behavior without interruption.
Where Are the Baby Honu?
This is one of the most common questions people have after seeing adult turtles around Hawaiʻi. After hatching, young green sea turtles spend their early years in open-ocean habitats, where they are difficult for people to observe. In fact baby honu spend their first 5-10 years in the open ocean. The vast open sea provides shelter and a better chance to grow safely during their early “lost years”, especially to avoid predators. Eventually, they move into shallow coastal areas where they can find food and shelter once they become juveniles. That’s why you are much more likely to see a larger juvenile or adult honu while snorkeling than a tiny hatchling.
Do Honu Travel Far?
Yes! Hawaiian green sea turtles can make impressive migrations between their feeding areas and nesting locations. Many Hawaiian honu travel hundreds of miles to the Northwestern Hawaiian Islands to reproduce, with the majority of nesting occurring at Lalo, or French Frigate Shoals. Females can return to the same general nesting area where they hatched. After nesting, they return to their coastal feeding grounds around the Hawaiian Islands.
What Should You Do If You See a Honu?
If you’re lucky enough to encounter a honu while snorkeling, the best thing you can do is simply observe. Please do not touch, feed, chase, ride, or block a turtle’s path. Give resting turtles plenty of room and allow swimming turtles to move freely.
Honu are protected animals, and watching them from a respectful distance helps keep both the turtle and your experience safe.
The Next Time You See a Honu
The next time you spot a honu around Oʻahu, take a moment to watch what it’s doing. It might be grazing on limu, heading toward the surface for a breath, settling into a reef crevice for a rest, or slowly making its way along the coastline.
There’s a lot more happening beneath the surface than you might realize!