Coral sex is a wonder to behold. On a summer night, always around a full moon, corals somehow all know to release billions of sperm and eggs into the sea, turning the water into a pink miasma of sex. This spawning relies on precise environmental cues, which could get scrambled in climate change. That's why researchers are trying to get them to spawn in the lab.
This delightful photo was snapped by Heather Sullivan during a behind-the-scenes tour of the Horniman Museum in London. There, aquarium curator Jamie Craggs is leading Project Coral to study how climate change could impact coral reproduction.
As one part of the project, they're growing a Caribbean brooding coral species called Favia fragum, Craggs told me in an email. (Favia fragum is actually one of the few coral species that don't spawn, but they do release larvae into the water based on the lunar cycle.) The little purple popsicles are pieces of calcium carbonate tile, specially made for settling coral larvae. Once ready, they will be used in a feeding experiment.
These small pieces of coral are actually between one and two years old now, which gives you a sense of exactly how slowly they grow. That's why coral reefs, once destroyed, are so hard to restore.
Pictures: Heather Sullivan, NOAA