Shark Species Found To Be Biofluorescent, According To Study

A group of sharks living in the deeper parts of the ocean were discovered by scientists to be biofluorescent - or glowing - to become more visible to each other in the dark waters, presumably for mating purposes.

Sharks are not the only bioluminescent species in the ocean - planktons, for instance, are known to light up beaches. However, according to National Geographic, this phenomenon is actually more widespread and more important than they previously believe it to be.

The research published in Scientific Reports described biofluorescence in two species of catsharks - the chain catshark or Scyliorhinus rotifer and the swell shark or Cephaloscyllium ventriosum. These sharks are relatively small and are no more than three feet in length. They spend most of their time on the bottom of the ocean, at around 1,600 to 2,000 feet in the deep waters.

After studying these catsharks extensively, scientists found that they have special pigments on their skin that absorbs blue light that then re-emits the color as green in a process called biofluorescence. Though both processes come to mean giving off light, bioluminescence is where animals produce their own light through various chemical reactions, not absorb it.

In order to figure out how these sharks see underwater, scientists created a "shark-eye" camera to mimic their vision. They then donned scuba gears and swam into the Scripps Canyon, where they found themselves on a lookout for the fascinating creatures.

Through the shark-eye camera, they were able to see the sharks glow a bright green. The glowing patterns for both species were also distinct between the species - female swell sharks have female "face masks" of spots and dense ventral spotting that extend further on their bodies than males.

Chain catsharks, on the other hand, have light and dark fluorescent patterns, but no spots. For the males, their pelvic claspers, which they use in mating, also glow.

Until recently, scientists thought that sharks relied on different senses to find their way around their environment, but this recent study showed otherwise. David Gruber, lead author of the study, shared that their findings showed a different viewpoint on how these creatures live so far beneath the surface. He also said that he hoped this will push humans to finally protect these species better.