Researchers have filmed a shark that glows in the dark off the coast of Santa Barbara, California, descending into the depths in order to document the animals in near complete darkness.
The sharks have been filmed as part of a Discovery/ BBC collaboration by Dr. David Gruber, an associate professor of biology at City University of New York. Utilizing cameras with yellow filters to block out natural blue light in the same manner that the shark’s eyes naturally do, Gruber filmed the species of swell shark (Cephaloscyllium ventriosum) displaying biofluorescence, a bright green glow that is created by proteins inside the shark’s skin. This trait is triggered by blue light, which represents the wavelength least absorbed as light travels through water.
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“On land we have the whole range of colors in the [visible] spectrum, as soon as you drop beneath the sea you quickly lose the reds and the violets and it becomes a monochromatic blue environment,” Gruber notes. “What the swell sharks are doing is using the blue light to create other colors of light to make their world richer in color.”
Biofluorescence is thought to be a form of communication between the sharks, which can see the glow with their naked eyes, unlike humans. Each shark displays a unique pattern of spots, as 9 News reports, which is endemic to that particular animal. Biofluorescence is also not limited to the sharks, but rather is utilized by a number of species that frequent depths of 500m (1,640ft), where the swell shark is often found.
“It’s almost like there’s been this disco party going on underwater and it’s possibly been going on for millions of years and we’re just beginning to tune into it,” Gruber observed.
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While the swell shark may be one of the more interesting species of shark, they certainly aren’t alone off the California coastline. As the Inquisitr has recently reported, a number of juvenile white sharks have been spotted close to the shoreline in Southern California recently, alarming beachgoers, though no adverse incidents have occurred.
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During a previous study, Gruber was part of a team that discovered biofluorescence in over 180 species of fish. Some researchers have asserted that this quality actually can act as a kind of camouflage, since a great deal of underwater fauna, like coral, is also biofluorescent. The swell shark’s glow-in-the-dark skin, therefore, might actually help it to blend in.
[Image: David Gruber and Vincent Pieribone via IFLScience]