Museum Researchers Discover Glowing Sea Turtles

by AMNH on

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For creatures that live underwater, it can be hard to get light, so many marine species have developed specializations to make their own light, a trait called bioluminescence. Others repurpose the light that does get through to them, sending it out in different colors, which is known as biofluorescence. Recently, researchers with the Museum made the first observation of biofluorescence in a wild sea turtle—one which glowed in bright neon hues when viewed under a blue light.

Hawksbill Fluorescence
A wild hawksbill sea turtle exhibiting biofluorescence, observed for the first time by a Museum researcher.
© AMNH/D. Gruber

Previously, biofluorescence has been observed in many marine creatures, including corals and fishes. But late last year, marine biologist David Gruber, a professor at Baruch College and a research associate at the Museum, captured the first footage of a sea turtle exhibiting the trait.

While the garishly colored light produced by biofluorescence is usually not visible to the human eye, the use of specialized blue excitation lights and green emission filters can reveal it. On a night dive in the Solomon Islands, Gruber encountered an endangered hawksbill sea turtle (Eretmochelys imbricata) that swam near the blue LED light he was using to excite biofluorescence in nearby corals. To his surprise, the turtle also lit up, exhibiting bright shades of neon green and red. The results of further study on the phenomena were published in the journal American Museum Novitates by Gruber and co-author John Sparks, curator in the Museum’s Department of Ichthyology.

While biofluorescence was once considered a rare trait, this discovery is the latest piece of evidence suggesting the quality may be common among marine species. The Museum’s 2013 Explore21 Expedition to the Solomon Islands, led by Sparks, discovered biofluorescence and bioluminescence in many unexpected species. 

Loggerhead Fluorescence
Biofluorescence was also observed in a loggerhead turtle at Mystic Aquarium in Mystic, CT.
© AMNH/D. Gruber

In this latest study, it may not only be the turtle that is biofluorescing. The red fluorescence on its shell, say the authors, is likely emitted by algae living there. Further study showed that the hawksbill was not alone among turtles with the specialization—a loggerhead turtle (Caretta caretta) in an aquarium also glowed bright green when exposed to blue LED light.