When diving under the sea at night, you would expect everything to be pitch black and hard to see, right? Well, marine biologist David Gruber saw something fluorescent in the sea when he and his team were in the Solomon Islands in late July. It was a sea turtle: a glowing sea turtle.
A glowing sea turtle sounds unreal, like it is too good to be true. But, bio fluorescence is not completely unheard of. Gruber and his team were in the Solomon Islands specifically for that reason, though they weren’t expecting to see it in sea turtles; they were there to film bio fluorescence in small sharks and coral.
Gruber and his team were on a night dive, keeping their eyes out for crocodiles, when the shocking discovery came about. Gruber recalled to National Geographic that, “it looked like a big spaceship gliding into view: an alien craft with a patchwork of neon green and red all over its head and body.”
Gruber followed the hawksbill turtle around for a little bit, capturing its fluorescence on camera. The camera had a yellow filter on it which allowed Gruber to pick up on fluorescent organisms. The only artificial illumination from the camera was a blue light, which matched the blue of the ocean. This did not alter the fluorescence of the sea turtle because the light matched the ocean.
Bio fluorescent organisms, such as coral, some fish, sharks, rays, cope cods, and mantis shrimp, are able to reflect blue light hitting a the surface and re-emit it as a different color. These colors are typically green, red, and orange. The sea turtle that Gruber found was emitting neon green and red.
Because Gruber only followed the sea turtle around for a short amount of time so that he was not harassing it, he turned to locals for help. He found a nearby community who held captive a few young hawksbill sea turtles. When examining them, he discovered that they all had the bio fluorescent ability to glow red.
Despite his findings, Gruber and Alexander Gaos, director of the Eastern Pacific Hawksbill Initiative, think it is too early to say for sure why these hawksbill sea turtles have the bio fluorescent ability. There’s even the question of whether or not different populations of these sea turtles have the ability to “glow” in other locations.
As for the questioning of why these turtles “glow,” there is the theory of camouflage. Gaos explains bio fluorescence in other organisms to support this: “[Bio fluorescence is] usually used for finding and attracting prey or defense or some kind of communication.” But why would this specific sea turtle need more camouflage when they’re already hard to spot because of their shell? It could be because of their specific habitat. The bio fluorescence could help them conceal themselves in the coral reef rather than the rocky reef that their shell helps them blend into.
This finding has left Gruber with many questions: Can the sea turtles see this bio fluorescence? Where do they get this biofluorescent ability? Do other sea turtle species have this ability? Gruber is anxious to find out the answers to these questions, though it will be difficult because of the very protected and small population of the endangered hawksbill sea turtles.
To help with these questions, Gruber believes he may be able to study the closely related green sea turtle, but as for now, there is little known about the glowing sea turtle.