A giant luminous shark has been discovered by scientists studying sharks off the coast of New Zealand. Measuring almost 2 metres long, the Kitefin shark is now the world’s biggest known glow-in-the-dark vertebrate.
The phenomenon of living organisms that glow was once considered quite rare, with fireflies being the most well-known example, but each year biologists are discovering more glowing creatures, and plants.
Bioluminescence, as it is known, is caused by a chemical reaction within the organism that produces light energy, and many sea creatures are known to have it. Now three species of shark –the kitefin shark, the blackbelly lanternshark, and the southern lanternshark – can be added to the list.
All three are deep-sea sharks that live in depths of up to 1km. No sunlight can reach that deep. Scientists believe that they have evolved to glow, not so that they can see better, but as a form of defence.
Viewed from below, the sharks would be backlit against the bright surface water and easily exposed to any predators. By having glowing bellies the sharks will be better camouflaged.
The sharks, of which te kite shark is the largest, all live in what is known as the mesopelagic or “twilight” zone of the ocean, between 200 and 1,000 metres deep, beyond which sunlight does not penetrate. Seen from below, the sharks appear backlit against the bright surface of the water, leaving them exposed to potential predators without any place to hide.
Researchers suggest these three species’ glowing underbellies may help camouflage them from any threats that might strike from beneath.
At this stage this is still just a hypothesis 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,” the researchers wrote in a paper published in the Frontiers in Marine Science journal,
The Freaky loves bioluminescence.
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