Three species of shark that inhabit the twilit depths of the ocean just turned out to have been bioluminescent this whole time.
The kitefin shark, the blackbelly lanternshark, and the southern lanternshark have all been discovered to have softly glowing blue patterns on their skin, a first for sharks found in New Zealand waters.
Of those three, the kitefin shark, which grows up to 180 centimetres (5 feet 11 inches) long, is now the largest known bioluminescent shark in the world.
Bioluminescence is not an uncommon trait for living things to evolve. Even humans glow (although too faintly to actually see). It seems to be most useful for life forms that live in the dark – night-glowing fungus, insects in dark caves… and in the depths of the ocean, so deep that the rays of the Sun can’t penetrate the water.
In the mesopelagic, also known as the twilight zone, between 200 and 1,000 metres (650 and 3,300 feet) below the surface, bioluminescence is practically a way of life. It has been estimated that over 90 percent of all mesopelagic animals have some form of bioluminescence that they use in different ways.
In sharks, however, bioluminescence is not well-documented, nor extensively studied. Marine biologists Jérôme Mallefet and Laurent Duchatelet of the Université catholique de Louvain in Belgium have been leading an effort to redress this……More Here
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