The star coral here is preparing to spawn, holding a bundle of gametes in each of its mouths (about 100 of them in this shot). The bright green color at the ends of the tentacles is produced by the coral’s own sunscreen-like pigments while the brown color is produced by the algae living inside the coral’s tissue. The light pink color is the gamete bundles, each made up of 50-100 eggs glued together with sperm. Yes, that’s right… they’re hermaphrodites. Not every coral is, but in this particular species each individual animal makes both eggs and sperm. But one individual coral colony can’t fertilize itself, so it still has to find a partner to mate with. How do you find a mate when you’re stuck to the bottom of the ocean? Most spawning coral species solve this puzzle by sending their sperm and eggs to meet at the water surface, cleverly turning a three-dimensional problem into a two-dimensional one.
Cool reproduction story - fantastic pictures!
