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A Spectacular Discovery: Biofluorescent Honu in Solomon Islands

    By Jenny McAllister. October 4, 2015 - 10:19 pm

biofluorescent_turtleUnder the tropical waves of the Solomon Islands on July 31, 2015, night divers Markus Reymann and David Gruber found a bizarre creature: an endangered sea turtle glowing bright green and red. No, it’s not radioactive. The divers immediately began filming the biofluorescent hawksbill sea turtle, following it around before it swam away a few minutes later.

David Gruber, associate professor of biology at Baruch College in NYC and National Geographic emerging explorer, told Laura Geggel, a staff writer for Live Science, that this is an important find because this is the first time scientists have found biofluorescence in a reptile.

Geggel explained that biofluorescence occurs when an organism absorbs light from an outside source, such as the sun, transforms it, and then re-emits it as a different color. This is different from bioluminescence, a chemical reaction that helps creatures, such as fireflies, flash light. Some animals also host bioluminescent bacteria, such as flashlight fish.

In the past decade, biofluorescent findings have taken off and researchers have identified all sorts of “glowing” marine life such as fish, coral, eels, and sharks. The work is so groundbreaking that Gruber and his colleagues helped make a forthcoming Nova special called “Creatures of Light,” Gruber said.

During a TBA21-Academy expedition looking for biofluorescent sharks, with blue lights and a full moon, in shallow waters near Nugu Island, located in the Solomon Islands in the South Pacific, a “brilliant green” and red glowing turtle came along.

biofluorescent_turtle2“This turtle almost seemed completely attracted to the blue lights that we were filming with, and just swam right into me,” Gruber recalled.

Gruber said the shell glowed both red and green, but it’s likely the red glow came from biofluorescent algae. He also spoke to locals who kept captive juvenile hawksbill sea turtles, and found that they fluoresced green under a blue light.

This particular breed of turtle is found in the Caribbean Sea and Indo-Pacific Ocean, but is also critically endangered partly due to climate change, illegal trade, bycatch (in which commercial fishers catch turtles by mistake while collecting other fish) and hunting.

Gruber said that because it is difficult to study critically endangered animals, he will study biofluorescence in the loggerhead turtle first because they are more accessible.

Jane Lee of National Geographic wrote, “This find has opened up a whole universe of questions that Gruber is eager to explore. They include whether these turtles can see the biofluorescence, where they get the ability, how they’re using it, and whether other sea turtle species possess a similar ability.

Still, it’s anyone’s guess why turtles would need to glow.

“It could be a way for them to communicate, for them to see each other better, [or] to blend into the reefs,” which are also biofluorescent, said Gruber. “It adds visual texture into the world that’s primarily blue.”

Photos and video courtesy of,, and National Geographic.