Scientists have known for centuries that the moon alters Earth’s ecosystems through gravity. In the course of their studies, Levy and his colleagues revealed that not only do corals have light-sensitive neurons tuned to the dim blue wavelengths of moonlight, they also have genes that change their activity level in sync with the waxing and waning moon, regulating reproduction.
#DARK MOONLIGHT OCEAN FULL#
Sometimes they delay until the next full moon. If the sky is too cloudy, and the moon obscured, the corals will often not spawn. Yet the moon’s presence seems to be crucial. The moon is not the only environmental cue the corals use to achieve sexual synchrony on such a massive scale water temperature and day length also matter. There, drenched in moonlight, gametes from different colonies began to fuse and form free-swimming larvae, which would eventually settle on the seafloor, bud, and construct new coral citadels-a process now more vital than ever. Swimming near the surface of the sea that memorable night 12 years ago, Levy encountered dense pink mats of accumulating eggs and sperm. “You can watch videos, you can hear about it, but once you are actually in the midst of the biggest orgy on this planet, there’s nothing else like it.”Ĭorals continue to reproduce in the Great Barrier Reef today, though the sections that have escaped the ravages of climate change are rapidly shrinking. “It’s like the whole ocean wakes up,” says Levy, who now heads a marine ecology research team at Bar Ilan University in Israel. Fish, marine worms, and various predatory invertebrates zipped through the water, feeding on the coral confetti, which rose slowly from the reef in huge quantities. The first time marine biologist Oren Levy witnessed this phenomenon, in 2005, he was near Heron Island, off the east coast of Australia. Then, in stunning unison, numerous corals lose their seeds, which hover momentarily above their parents, preserving the shape of the reef in an effervescent echo. But most release both eggs and sperm, packed together in round, buoyant bundles as small as peppercorns and blushed in shades of pink, orange, and yellow.Īt first, the parcels wait in the lips of corals. Some corals spew plumes of sperm, smoldering like underwater volcanoes. One November night each year, beneath the full moon, more than 130 species of corals simultaneously spawn in Australia’s Great Barrier Reef. This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems.
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