Tuesday, August 17, 2004

Bacteria give coral its orange glow, study finds

WASHINGTON — 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 said Thursday.

And the bacteria not only give the coral a little night light but they also break down seawater to help nourish the coral, the researchers said.

Michael Lesser of the University of New Hampshire and colleagues were studying the Caribbean Great Star coral, known scientifically as Montastraea cavernosa.

It grows in formations that resemble large boulders or rock shelves and often emits a fluorescent glow, typical of the algae known as zooxanthellae. These are known to exist symbiotically with coral, providing their hosts with food such as carbohydrates.

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