Scientists off the coast of New Zealand discover three new deep-sea shark species. All three species glow in the dark. One of these sharks is now the largest known luminous vertebrae.
Bioluminescence: When a living organism produces visible light through a chemical reaction. The phenomenon is widespread among marine life. However, this is the first instance of bioluminescence documented and analyzed in the kitefin shark, the black belly lantern shark, and the southern lantern shark.
All three sharks appear in a fish survey from January 2020 in Chatham Rise, off the east coast of New Zealand.
The kitefin shark, which grows up to 180cm, is now the largest luminous vertebrae yet.
The researcher team includes scientists from the Université Catholique de Louvain in Belgium and the National Institute of Water and Atmospheric Research in New Zealand. The researchers say their findings have repercussions for understanding life in the deep sea.
All three shark species live in waters between 200 and 1,000 meters deep (657-3281 feet). Sunlight does not penetrate beyond this “Twilight zone” of the ocean. The sharks appear backlit against the bright surface of the water when seen from below. Without special adaptations, the sharks are easily spotted by predators underneath them.
The research team suggests that these three species’ glowing underbellies might camouflage them from predators lurking below.
The kitefin shark has no known predators. The shark might use its natural glow to illuminate the seafloor in search of prey. However, further research is required as this bioluminescence mechanism is poorly understood, according to an article published in the Frontiers in a Marine Science journal.
The research team claims that “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.” (Mallefet, Stevens, & Duchatelet 2021).
Lead researcher of the Marine Biology Laboratory at the Université Catholique de Louvain in Belgium, Jérôme Mallefet, is puzzled by how the kitefin shark’s bioluminescence works. Mallefet tells the Guardian, “The luminous pattern of the Kitefin shark was unknown, and we are still amazed by the glow on the dorsal fin. Why? For which purpose?”
The shark’s enormous territory makes studies like these a challenge. Mallafet and his team hope to be back on the water soon and continue looking for luminous sharks.