A team of scientists working with National Geographic this week got a beautiful surprise when a biofluorescent sea turtle popped into view. Its shell had a gorgeous plume-like arrangement of red, yellow, and green colors, which appear neon when light touches its surface.
Here's how biofluorescence works: Unlike bioluminescent animals, who literally glow from within because of the bacteria that live inside them (think glow worms or fireflies), biofluorescent animals reflect the blue light of the deep ocean and turn it into a different color. That's kind of mind-blowing, because clear ocean water absorbs every color except blue, once you get down to a depth of about 65 feet. That's why the ocean is blue, and why, typically, any light shining in the ocean looks blue, too.
So, when divers accidentally found this beautifully glowing biofluorescent turtle while using a light on some coral in a dive around the Solomon Islands, they were pretty excited.
"This turtle was just hanging out with us!" says Markus Reymann, the director of the mission, in a video shot by National Geographic, right after the dive. "It was in love with the light. It was just hanging out with us," he repeats, mystified. "And it was glowing yellow!" Then he bursts into joyful laughter.
The divers were shooting footage of coral reefs when the turtle unexpectedly showed up (and showed off) in front of the lens. Then, as marine biologist David Gruber described it, the creature "hung out with us for like five minutes ... I wanted to let him go after a few minutes. I felt like he came, and he divulged his secret."
The expedition was part of a new TBA21-Academy venture, which hooks up artists and scientists to work on projects celebrating the oceans and ocean life. This discovery builds on work done by the American Museum of Natural History, whose 2013 expedition in the same area first suggested that biofluorescence might be quite widespread. Other biofluorescent sea animals include marine eels (which are neon green), and goby fish, which are red
Like all good science, the discovery opens up more questions
"How are they using this?" asks Gruber. "Are they using it to find each other? Or are they using it to attract each other?.
According to the World Wildlife Fund, nearly all species of sea turtles are endangered due to being slaughtered for their eggs, meat, skin, and shells, or kept in rotten conditions in roadside zoos and aquariums.
"What's even more sad, I think, about this is that these turtles have such a storied history, and now they're critically endangered," reflects Gruber. According to the Sea Turtle Conservancy, only one in every 1,000 to 10,000 sea turtles hatched will survive into adulthood.