The Red Sea is known around the world for its beautiful and diverse coral reefs that extend for thousands of kilometers (1,200 miles, to be precise) around the shallow coastline. What is less well known, though, are the corals that live in the depths of the sea. But thanks to new research, scientists have now shown for the first time that these inhabitants produce a dizzying array of fluorescent colors.
Whilst surveying corals 50 meters (164 feet) below the waves, a team of marine biologists found that many of the deep sea corals produced a rainbow of pigments that glow under UV light. They were shocked to find such a striking range of colors, as corals that live in shallower waters are normally limited to producing green fluorescent pigments.
“Since only the blue parts of the sunlight penetrate to depths greater than 50 meters, we were not expecting to see any red coloration around,” explained Gal Eyal, who was involved in the study published in PLoS ONE. “To our surprise, we found a number of corals showing an intense green or orange glow. This could only be due to the presence of fluorescent pigments.”
The fluorescent colors are caused by specific proteins that, when illuminated by blue or ultraviolet light, reflect back light of a longer wavelength. This is the mechanism behind their mesmerizing glow, explained Jörg Wiedenmann, who leads the University of Southampton’s Coral Reef Laboratory that carried out the research in collaboration with other institutes in Israel.
“Their optical properties potentially make them important tools for biomedical imaging applications, as their fluorescent glow can be used to highlight living cells or cellular structures of interest under the microscope,” continued Wiedenmann. “They could also be applied to track cancer cells or as tools to screen for new drugs.”
Finding these pigments was unexpected: In shallower seas, they’re normally expressed as a form of sunscreen to protect the corals and their symbiotic algae from damage. Living 50 meters down, where the corals often struggle to get enough sunlight even for their algae to make use of, there is little threat of damage from overexposure to the sun. In light of this, the scientists plan on exploring what other role these pigments might play.
Watch a video of the incredible corals here:
Center image credit: Professor Jörg Wiedenmann