You shouldn’t be afraid of catsharks because, more often than not, they’re not harmful to humans. At the same time, there’s not much to look at, at least not in the daylight.
But use a blue light and you’ll see that some species have a gorgeous glow. Researchers have built a camera that mimics the way these glowing sharks see the surroundings – and each other – when they’re deep under the sea.
With the help of this lens, the eerie glow only grows stronger as the sharks swim deeper. The results of the study were featured in Scientific Reports on Monday.
Co-author on the paper John Sparks, a curator at the American Museum of Natural History’s Department of Ichthyology, explained that even though we already knew that catsharks can be brightly fluorescent under the right light, this work takes that research a step further.
The new research shows that biofluorescence helps catsharks better see the members of the same species. The case is made for the “connection between visual capability and fluorescence emission,” as it aims to explain the fluorescence in fishes.
Back on September 23, there were reports of a drone fitted with a camera that recorded footage of hundreds of sharks swimming around a sandbar near Destin, Fla.
After he saw a group of sharks in the water, a fisherman thought of launching the drone to get a better look. The sharks he filmed were all medium-sized black-tips, no longer than 5 to 7 feet.
Because they live around 2,000 feet below the surface of the ocean, the chain catshark (Scyliorhinus retifer) and the swell shark (Cephaloscyllium ventriosum) have been largely neglected by the scientific world.
However, Sparks and his colleagues spend most of their lives around these sharks, and at that depth, the vast majority of wavelengths of visible light are absorbed by water, thus leaving animals with mostly blue hues.
This is what gives them biofluourescence; unlike bioluminescence, this light is not produced by the organism, but absorbed from the environment and re-emitted as other colors.
Because humans can’t see these colorful displays, the researchers created a color filter that mimics the fishy vision. Even though the researchers could only dive to more shallow regions, mathematical modeling suggests the colors only pop more as the water gets deeper (and bluer).
More research is needed before researchers can be sure that the sharks have a significant glow under natural conditions. There are other species, like the biofluorescent a sea turtle discovered last year, which have prompted scientists to pay more attention to this rare phenomenon.
Image Source: YouTube