Scientists have discovered three species of glowing sharks in the deep ocean near New Zealand, reports Elle Hunt for the Guardian. One of the species, the kitefin shark, can reach lengths of nearly six feet and researchers say its cool blue glow makes it the largest known species of luminous vertebrate on Earth.
The three bioluminescent sharks—the kitefin shark, the blackbelly lanternshark and the southern lanternshark—were hauled up from the deep during fish surveys of an ocean bottom feature called the Chatham Rise off the east coast of New Zealand in January 2020. All three sharks inhabit the ocean’s mesopelagic or “twilight” zone, which spans depths of 660 to 3,300 feet below the surface.
Bioluminescence is relatively common in the deep sea among fish and squids, but its presence has been murkier and less well-studied among sharks, reports Elizabeth Claire Alberts for Mongabay. A study detailing the discovery, published last month in the journal Frontiers in Marine Science, confirms the three sharks’ bioluminescence but suggests their biochemical mechanism for producing light may be different from most sea creatures, per Mongabay.
Most bioluminescence in the deep sea involves a chemical compound called luciferin that glows when it interacts with oxygen. Researchers tell Mongabay that this trio of sharks appears to produce light some other way.
Researchers aren’t exactly sure what purpose the ability to glow serves for the sharks but speculate that their glowing bellies could make them harder to see from below. In the darkness of the deep sea, the ocean surface is a faintly luminous backdrop against which a glowing shark would disappear when viewed from below, concealing it from predators or prey. Per the Guardian, the kitefin may also be using its glow to illuminate prey on the seafloor.
“I tend to say they are the MacGyver users of light, because they use bioluminescence in many different ways,” Jérôme Mallefet, a marine biologist at the Université Catholique de Louvainthe and the study’s lead author, tells Mongabay.
Curiously, the kitefin’s dorsal fin also emits light. Speaking with the Guardian, Mallefet says “we are still very surprised by the glow on the dorsal fin. Why? For which purpose?”
Mallefet says he hopes he will soon be able to safely travel for his research and continue investigating the glowing denizens of the deep. “We hope by highlighting something new in the deep sea of New Zealand—glowing sharks—that maybe people will start thinking we should protect this environment before destroying it,” he tells Mongabay.
“I hope the new generation will carry that message, and I’m more than happy to [add] my little piece of the jigsaw to a big program to protect the ocean,” Mallefet says.