Researchers diving off the Solomon Islands recently made a startling discovery, documenting a glowing sea turtle that is reportedly the first marine reptile ever to display biofluorescence.
The discovery was made by marine biologist David Gruber, of City University of New York, according to National Geographic. Gruber had traveled to the Solomon Islands in late July with the goal of filming biofluorescent animals, specifically small sharks and coral. Biofluorescence is distinctly different from bioluminescence. In the former, animals absorb light and then emit it in a different color. In the latter, organisms actually produce light by way of a chemical reaction.
During one of the research team’s night dives, Gruber spied an unusual object gliding into view, coming face-to-face with something he had hardly expected to see: a glowing sea turtle.
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The animal, a hawksbill sea turtle, was glowing with a patchwork of neon green and red all over its body. Gruber was able to document the glowing turtle, filming it with a special system designed to record biofluorescence. In this system, artificial illumination is achieved through use of a blue light (intended to match the surrounding seas), while the lens is equipped with a yellow filter.
Gruber’s video is unprecedented, as a marine reptile has never before been recorded exhibiting biofluorescence. As io9 relates, a wide variety of fish (including copepods, mantis shrimp, sharks, and rays) have demonstrated the trait in the past, yet no sea turtle has ever been proven to be capable of fluorescing.
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While filming the glowing turtle, Gruber only followed it for a few moments, not wanting to harass the endangered animal. The hawksbill turtle eventually disappeared into the depths, but with an eye toward gathering more data, Gruber spoke with locals regarding his discovery. He visited a nearby community and learned that they in fact kept several young hawksbill sea turtles captive. After examining those specimens, Gruber found that they too glowed, displaying the same ability to fluoresce.
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Researchers assert that it is too early to tell whether the ability to fluoresce is specific to the Solomon Islands’ population of sea turtles, or whether specimens in other regions might also be capable of glowing. Though biofluorescence is used for a variety of reasons by animals, Gruber believes that the sea turtles in the Solomon Islands may use it as a form of camouflage, blending in with a coral reef that also glows. During the daytime, the turtles’ shells provide another ready source of concealment, allowing them to blend into the background of a rocky reef.
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Hawksbill sea turtles are a critically endangered species, and sadly, one of the rarest on the planet. They largely remain a mystery to researchers, but Gruber hopes he can study their closely related (but far more common) relatives, the green sea turtle, in an effort to determine whether other species of turtle can demonstrate the same ability. He also notes that the next logical steps are to determine whether or not the turtles can see the biofluorescence (indicating that it could be used for communication), and how they have developed the ability. Researchers will be particularly interested in whether the Solomon Islands’ glowing sea turtles produce the required compounds themselves, or ingest them as part of their diet.
Gruber’s video of the Solomon Islands’ glowing sea turtle can be viewed at National Geographic.