Sharks use unique molecules to make green

deep in the ocean, some species of sharks convert the blue light of the ocean into bright greens that only other sharks can see, but how they emit biofluorescence has not been clear. In a study published in iScience, researchers found what causes sharks to appear bright green: a previously unknown family of small molecular metabolites.
this biofluorescence mechanism is not only different from that of most marine organisms, but may also play other roles for sharks, including helping them identify and fight microbial infections in the oceans.
" study of biofluorescence in the oceans is like reading an evolving mystery novel, with new clues emerging as research advances. David Gruber, co-author of the paper and a professor at the City University of New York, said.
are probably the most famous fluorescent marine organisms that emit bright greens and blues, and scientists use their proteins to track proteins in cells and even create cats that glow in the dark. In their search for more similar proteins, the researchers looked at 180 species of glowing fish, known to focus on chain cat sharks and swelling sharks, which live off the coast of Southern California and in the Northeast.
when the compounds were extracted and analyzed from a piece of skin of a live shark, they were surprised to find that the luminescent compounds were not proteins at all, but the product of an unusual form of decomposition of tryptophan. In animals, most tryptophan is used to make proteins. But some of them are converted into a compound called canine urea, which is a essential ingredient in nia acid, a vitamin, linked to diabetes, inflammation, depression and even cancer. When an atom of the bromine element follows, canine urea emits green light when exposed to blue light beneath the ocean's surface, the team said.
these sharks usually live on the ocean floor, waiting for the opportunity to ambush octopuses and other marine life. No one really knows why they glow, although this may help sharks distinguish between each other or identify potential mates, as males and females have different fluorescent patterns.
these compounds can also protect sharks because one of the luminescent compounds kills bacteria. Given that these animals roll in bacteria-rich sediments on the ocean floor, antibacterial properties may also come in use. (Source: Tang Erdu, China Science Journal)
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