One of Hawaiʻi’s most beloved marine animals may have a surprising new job: helping protect coral reefs.

Researchers from the University of Hawaiʻi at Mānoa and the U.S. Fish and Wildlife Service recently documented Hawaiian green sea turtles, known as honu, actively feeding on an invasive red algae called Chondria tumulosa. This is the first time scientists have observed honu grazing on this aggressive seaweed, which has been spreading throughout the Northwestern Hawaiian Islands.

The algae forms thick mats that smother coral reefs and crowd out native marine life. It has already spread across more than 100 square kilometers of reef habitat within Papahānaumokuākea Marine National Monument, making it one of Hawaiʻi’s most concerning marine invasive species.

Using underwater GoPro cameras, researchers captured several honu taking repeated bites from the algae, clearing patches much larger than fish or sea urchins typically can. While this natural grazing may help slow the algae’s growth, scientists are also studying whether turtles could unintentionally transport small algae fragments between islands during their migrations.

For visitors exploring Maui, spotting a honu is always a memorable experience. These protected sea turtles play an important role in Hawaiʻi’s marine ecosystem, and discoveries like this highlight how interconnected nature truly is.

If you’re visiting Maui, remember to admire honu responsibly. Federal guidelines recommend staying at least 10 feet away, never touching or feeding them, and allowing them to rest undisturbed on the beach or in the water.

At Kihei Rent A Car, we’re proud to share stories that celebrate Hawaiʻi’s incredible wildlife and the ongoing efforts to protect these islands for future generations. Whether you’re exploring South Maui’s beaches or driving the scenic coastline, every adventure offers another opportunity to appreciate Hawaiʻi’s remarkable natural world.