The ability for living organisms to produce visible light through a chemical reaction is known as bioluminescence, and it’s one of the most spectacular phenomenons found in nature.
Bioluminescence has been observed in a wide range of marine life such as jellyfish and algae, but recently, marine biologists came across the phenomenon in a trio of different sharks.
During a fish survey off the east coast of New Zealand, scientists observed three different sharks glowing deep beneath the waves: the blackbelly lanternshark, the southern lanternshark, and the kitefin shark, with the latter being the largest-known luminous vertebrate ever observed. All three species were found to have glowing underbellies, and all of them live in the “twilight” zone of the ocean where sunlight does not penetrate.
In a paper published in the Frontiers in Marine Science journal, the scientists hypothesize that the kitefin shark, which has little to no predators, might use its natural glow to illuminate the ocean floor while it searches for food, or to disguise itself in approaching its prey. That hypothesis must still be confirmed, as well as a number of different questions about the sharks’ glow.
“The luminous pattern of the Kitefin shark was unknown and we are still very surprised by the glow on the dorsal fin,” said Jérôme Mallefet, lead researcher from the Marine Biology Laboratory of the Université Catholique de Louvain in Belgium. “Why? For which purpose?”
Image source: Dr. J. Mallefet — FNRS, UCLouvain