Researchers have pinpointed the reason that deep-water corals emit an eerie glow: to help their algae do photosynthesis.
Scientists know that in shallow waters, the organisms light up green, using fluorescent proteins as a kind of sun block. The proteins soak up harmful ultraviolet rays, re-emit green light and shield their symbiotic algae, which supply most of the corals’ energy needs through photosynthesis.
In 2015, a team led by Jörg Wiedenmann at the University of Southampton, UK, found that deep-dwelling corals also fluoresce — this time in an array of vivid yellows, oranges and reds. Some of these organisms live in water as deep as 165 metres, where little sunlight reaches them, and most of what does is in the blue part of the spectrum. So the researchers suspected a different reason for the glow. Read more