This archive report was first published on 11 August 2019.
Deep in the ocean, where sunlight barely reaches, lies a world of mystery and beauty. Scientists have long been fascinated by the ability of certain sharks to glow in the dark, a phenomenon that has left researchers scratching their heads for years.
According to a study published on August 8, 2019, in the journal iScience, researchers have finally uncovered the secret behind this magical transformation. The study reveals that molecules inside the scales of the swell and chain catshark transform how shark skin interacts with light, bringing in blue photons and sending out green.
‘I think this is just yet another amazing feature of shark skin that we didn’t already know about — just adding to their list of superpowers,’ said David Gruber, a marine biologist at City University of New York and an author on the paper.
Shark skin is unlike any other skin in the animal kingdom, plated in toothlike scales called denticles. To find the hidden beauty of these sharks, Dr. Gruber worked with Jason Crawford, a biochemist at Yale University, and other colleagues. Under the microscope, they noticed several types of dendrites that emitted green light of varying intensities in response to blue light.
Examining the skin more closely, the team found a set of molecules that were derived from tryptophan, an amino acid important for sleep and mood in humans. These molecules also contained bromine, which changes how the molecules, and essentially the skin, interacts with light.
Many fluorescent marine animals seem to have evolved their own techniques for transforming light. The most well-studied among them is the use of green fluorescent protein, which can make neon rainbows out of jellyfish, corals and other animals in shallower depths. But the sharks’ process was unlike any of these.
