Coral reefs have been struggling in recent years, with reports that huge swathes of it had succumbed to coral bleaching; the Great Barrier Reef had its most devastating die-off ever recorded in 2016, as CNN reported at the time. Bleaching happens when ocean temperatures get to hot.
As Stephanie Wear, The Nature Conservancy’s director of coral reef conservation, told Nature, the color from coral actually comes from tiny algae that live symbiotically with it.
“The first thing to understand is that corals get their brilliant colors from tiny algae that live in their tissues. These tiny organisms live in harmony with coral animals, and they basically share resources,” Wear explains. “For example, the most important thing that the algae do is provide food to the corals through carbohydrates they produce during photosynthesis."