How This Shark Uses A Mysterious Process To Glow Underwater

Although blockbuster cinemas and the movie industry in itself have always depicted them as vicious, deadly and bloodthirsty creatures (we have Spielberg’s "Jaws" for starting that trend), sharks are actually timid, even shy, creatures. In fact, aside from the great white, bull and mako sharks, the vast majority of their species would rather stay away from humans than get close to them and attack.

However, while they mostly keep to themselves, that’s not to say that some sharks have no flair whatsoever. A good example of this is the swell shark and the chain catshark. While both sharks usually spend their time resting on the sea floor and away from prying eyes, both are known to provide a green glow when exposed to light.

To understand the science behind this bioluminescence, scientists then studied the sharks. And what they discovered is something they’ve never seen before.

Underwater Glow

Out of all the fluorescent sea creatures we know of today, glowing jellyfishes are probably the most well-known and famous. Scientists have long studied these creatures, and have long discovered that their brilliant glowing green and blue hues are due to a protein found in their bodies.

Previously, the scientists focused on the aforementioned sharks believed that the same proteins, or at least a variation of it, are responsible for their glowing nature. However, they found something entirely different. After extracting all the compounds in a piece of the shark’s skin, they found not proteins, but an unusual type of trypophan, an amino acid. Now this isn’t that big of a difference since animals mainly use the amino acid to create protein. However, the scientists also discovered that some of the trypophan gets converted to kynurenine, which, when combined with the element bromine, releases a glow after being exposed to light.

Despite this discovery, scientists are still unsure as to why they glow, whether they use it to attract prey, find a partner or to simply recognize and tell each other apart. One of the robust explanations however, is how they use it for protection since one of the glowing compounds can kill bacteria present in their skin.

sharks Sharks may seem like the deadliest creature around, but there are other, more unlikely killers to be afraid of. Guillaume Baviere, CC BY-SA 2.0.