Scientists have long known that catsharks produce a bright green fluorescence underwater, but a new study has added some very interesting observations to their knowledge about these interesting underwater creatures. To learn more about them, researchers used a custom-made camera that simulates the way catsharks see. Their findings were published in the Scientific Reports journal.

Catsharks Communicate Via Their Own Fluorescent Lighting

Camera reveals new findings on catsharks

Phys.org reports that American Museum of Natural History scientists led the team that conducted the study. Using the special camera, they learned that catsharks are able to see the fluorescence they give off and also that they increase the contrast of this fluorescence when they go deeper under water.

Scientists learned that the fluorescence actually enables catsharks to see each other better underwater, especially at the depths they live in. They believe that the green fluorescence could also help the sharks communicate. One of the paper’s coauthors said it is the first that demonstrates a link between the fluorescence catsharks give off and their visual capabilities. He also said their findings offer a “functional explanation for fluorescence in fishes.”

What is fluorescence?

Phys.org describes the fluorescence the researchers studied as “a phenomenon by which organisms absorb light, transform it, and emit it as a different color.” Researchers have identified more than 180 different kinds of fish that give off bio-fluorescence in various colors and different patterns. The environment in which fish live is mostly blue, and the deeper the depth they are in, most of the visible light colors are absorbed by the water. Many kinds of fish then absorb what’s left of the blue light and emit it in neon colors, including green, red and orange.

To conduct their study of catsharks, the researchers designed lighting that mimics the light in the ocean and cameras that capture the fluorescence given off by fish. They then traveled the world and used the cameras to capture the bio-fluorescent underwater world. They were also the first to observe marine turtles giving off bio-fluorescent light.