Caribbean Coral Gets Glow From Bacteria

The soft orange glow of a common Caribbean coral comes not from the coral itself but from bacteria that live inside it, U.S. scientists reported in this week’s Science. And the bacteria also break down nitrogen molecules in seawater to produce ammonia that helps nourish the coral, the University of New Hampshire researchers said.

The Caribbean great star coral, known scientifically as Montastraea cavernosa, grows in formations that resemble large boulders or rock shelves and often emits a fluorescent glow, typical of the algae known as zooxanthellae. But the coral also glows during the day, and that glow is produced by the cyanobacteria, they said.