( Certain species of coral have surprised...)Tiny polyps gorge themselves to survive coral bleaching

Their innovative strategy is gluttony.

The discovery, derived from experiments on coral reefs in Hawaii , provides new insights into how these tiny animals face a multitude of environmental threats. The report by Ohio State University researchers is published in the current issue of the British journal Nature.

During the past decade, reports have multiplied of major bleaching events that have damaged, if not destroyed, large portions of the world's fragile coral reefs. Scientists point to global warming as the cause and the victims are some of the tiniest creatures near the base of the undersea ecosystem.

Despite the apparent sturdiness of coral reefs, the creatures themselves are quite fragile. These tropical organisms survive in a narrow 4-to-6-degree C temperature range centered about 26 degrees C. While the exact temperatures vary with individual species from location to location throughout the tropics, they all must live within that tight range.

When the temperature climbs above that range, even by only two degrees, the result is a bleaching event. Within a two-year window during the 1997-98 El Nino event, 16 percent of the world's coral reefs sustained serious bleaching due to increases in seawater temperature and the animals died.

"If the rain forests were dying off at this rate, we would all be panicking," explained Andrea Grottoli, an assistant professor of geological sciences at Ohio State and lead author of the study.

"The problem is that now, with the planet's climate warming, coral are living closer and closer to their thermal threshold, so it takes less of a warming event than it did before to cause a catastrophe."

Coral are symbiontic organisms that host one-celled algae within their bodies for mutual benefit. The coral polyp, a relative of je
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Source:Ohio State University