Glow-in-dark sea turtle discovered: Mutant, maybe, but definitely not a ninja

On a diving expedition, marine biologists found a glowing hawksbill sea turtle – the first instance of a reptile observed to be biofluorescent.

|
Romeo Gacad/AFP
A hawksbill turtle hatchling crawls beside an egg at a breeding center at the Thousand Islands National Marine Park in Pramuka island, north of Jakarta, April 20, 2010. Hawksbill turtles, known by their scientific name Eretmochelys Imbricata, are listed as an endangered species by the International Union for the Conservation of Nature and Natural Resources.

It was like a dazzling spacecraft, the scientist recalls.

Beautifully striped, like an incandescent UFO gliding through the ocean floor, the hawksbill sea turtle was glowing — the first known instance of a reptile exhibiting biofluorescence, an ability to absorb the blue light of the water and emit it as a different color. In other biofluorescent animals, the gleaming result is often neon green, red, and orange.

Marine biologist David Gruber had been in the Solomon Islands in late July to film biofluorescence in the South Pacific, reports National Geographic. While searching for glowing coral reefs and small sharks, Gruber and his team instead encountered a luminous and very friendly turtle.

"Out of the blue, 40 minutes into the dive – it almost looks like a bright red and green spaceship – it came underneath the camera," Dr. Gruber says in a video. "It just bumped into us.... Came in front of my lens and then hung out with us for five minutes."

Ecstatic about his find, the marine biology professor at City University of New York explains that the only animal known to glow two colors is coral. Other sea creatures that glow through biofluorescence include sharks, sea horses, a number of fish, and tiny crustaceans called copepods.

Biofluorescence differs from bioluminescence, which is a chemical reaction within the body that creates radiant light. Bioluminescent animals include jellyfish and deep sea fish, who use their glowing to navigate, communicate, and lure prey.

Gruber and his team recorded the turtle before it dove deep into the dark waters using a video camera that emitted an artificial blue illumination identical to the blue light of the ocean. Later, when the marine biologist found a local community that kept several captive young hawksbills, he found that they all glowed red.

"I've been [studying turtles] for a long time and I don't think anyone's ever seen this," Alexander Gaos, director of the Eastern Pacific Hawksbill Initiative, told National Geographic. "This is really quite amazing."

Neither Mr. Gaos nor Gruber is sure why the hawksbill sea turtles biofluoresce. Gaos, who was not involved in the discovery, speculated that It could be a kind of camouflage in this instance.

Even without biofluorescence, hawksbill sea turtles have famously colorful shells, which led to massive population declines as the animals were hunted to make tortoiseshell products.

Named for their birdlike beak and narrow head, these turtles feed mostly on sponges and linger in rocky areas and coral reefs. They have a mutually beneficial relationship with corals, as the sponges the turtles consume can suffocate reefs. The largest hawksbill populations are in the Caribbean Sea, the Seychelles, Indonesia, Mexico, and Australia.

Globally, hawksbill sea turtles are critically endangered. Just in the last century, they’ve diminished by more than 80 percent. Before international tortoiseshell trade became illegal, they were hunted almost to extinction. Today, their populations are jeopardized by poaching, entanglement in fishing nets, destruction of habitat, coastal development, and climate change. Nearly all sea turtle species are endangered.

Even though his encounter with the turtle was brief, Gruber says it was enough to show that turtles are biofluorescent and to open up a new discussion on why that might be.

"I wanted to let him go after a little bit," he says. "I feel like he came and divulged a secret."

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to Glow-in-dark sea turtle discovered: Mutant, maybe, but definitely not a ninja
Read this article in
https://www.csmonitor.com/Science/2015/0929/Glow-in-dark-sea-turtle-discovered-Mutant-maybe-but-definitely-not-a-ninja
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe