Scientists have discovered three species of deepwater sharks that glow in the dark near New Zealand’s coast.
The largest of the three, the kitefin shark, is the largest known luminous vertebrate, with lengths up to 5’11”. The blackbelly lanternshark and the southern lanternshark also glow in the dark, the BBC reported.
Marine biologists knew of the three shark species before. But they didn’t know that the sharks glow in the dark. Scientists call the trait bioluminescence, meaning organisms that give off light.
Researchers Find Glow-in-the-Dark Sharks
Researchers from New Zealand’s National Institute of Water and Atmospheric Research and Belgium’s Universite Catholique de Louvain found that the sharks glow in the dark by studying an area known as the mesopelagic zone, or the twilight zone, which lies at the maximum depth reached by sunlight.
They looked at sharks from the Chatham Rise, a span of ocean floor just east of New Zealand. The researchers conducted their study last January.
Their research, published in Frontiers in Marine Science, describes how the creatures give off light through thousands of light-producing cells within their skin.
The researchers believe the bioluminescence is an evolutionary adaptation that allows the sharks to hide from predators swimming underneath them. The sharks inhabit a landscape without hiding places, and their glowing acts as a form of camouflage, the researchers surmised.
They believe the bioluminescence was “co-opted during evolution” from skin pigment movement regulation. The researchers further assume hormonal control of the bioluminescence.
More Research Needed to Understand Phenomenon
“Bioluminescence has often been seen as a spectacular yet uncommon event at sea, but considering the vastness of the deep sea and the occurrence of luminous organisms in this zone, it is now more and more obvious that producing light at depth must play an important role structuring the biggest ecosystem on our planet,” they wrote.
The researchers added that their study is the first of its kind, and it provides insight into the diversity of shark bioluminescence. Moreover, they said, their study underscores the need for more research to understand deep-sea inhabitants, particularly glowing sharks.