Elkhorn coral, with branches as large as 12 feet in diameter, are hermaphroditic marine animals that usually reproduce asexually. However, once a year, when the moon is full, in a symphony of synchronized sexual reproduction, they release eggs and sperm that float up to the ocean surface where fertilization happens. The fertilized embryos become larvae that eventually cement on the ocean floor as hand-like polyps. A single tiny polyp divides many times to produce a massive coral colony slowly over centuries. Elkhorn corals used to form dense zones on Caribbean reefs that harbored many diverse creatures but since the 1980’s, 90-95% of these majestic creatures have been lost to disease and coral bleaching. Bleaching occurs when seawater temperatures rise, triggering corals to expel the colorful algae cells that typically provide them with food. Without their algal partners, corals are ghostly: their bleached white limestone skeletons show through transparent, starving coral tissues. Coral bleaching has been ongoing since 2014 through today as part of the 3rd global mass bleaching event; climate change is likely now the single greatest threat to stony corals.
Art by Carrie Schneider