The Secret Sex Lives of..............
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(Clickbait title. 555)
....... deep, dark corals.
Back in the borrowed government fisheries lab on Chiloé Island, 28 D. dianthus specimens hang suspended in tanks within a larger tank, which cools them with a constant bath of filtered seawater, like a frigid bain-marie. For the month of July while the scientists live here, losing track of time in the dark and cold, Chiloé is Love Island for the coral contestants. Unlike most tropical corals, where entire reefs are made up of genetically identical polyps, D. dianthus is a solitary coral—each polyp is genetically distinct. That means the sex of a given specimen plucked from the fjord remains a mystery until it’s ready to reveal itself with a stream of eggs or spurt of sperm. “It would be wonderful if they color-coded themselves or something, but they don’t,” says Waller. “So we just have to watch and wait for them to really show us who they are.”
They may lack brains, but each individual coral seems to have a mind of its own, and after weeks the team has gotten used to the corals’ distinct personalities. Some tolerate the light of a flashlight or the slam of a door; others curl their tentacles at the slightest disturbance, preferring privacy—they’ll only do it with the lights off. The researchers running this show have their patience tested coaxing the coral contestants to cooperate. “They all do their own thing,” says Waller. “If they’re happy, they’ll spawn well; if they’re unhappy, then they just close up.”
Tonight, both males and females have chosen to spawn. After the team collects sperm—a frantic endeavor, as it dilutes quickly into the water—Waller and Acevedo-Romo set to work pipetting up eggs that have settled to the bottom of the tanks. Meanwhile, Morán crouches over a microscope, painstakingly counting individual sperm to determine concentrations and how far they can travel in the water to successfully reach and fertilize eggs.
