coral reef

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Learn how hermaphroditic coral reproduces once a year after a full moon in good water conditions

Learn how coral bleaching occurs when stressed zooxanthellae algae leave because of rising water temperatures

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coral bleaching near the Mariana Islands

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coral reef summary

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Charles Darwin, carbon print photograph by Julia Margaret Cameron, 1868.

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Queen Elizabeth II addresses at opening of Parliament. (Date unknown on photo, but may be 1958, the first time the opening of Parliament was filmed.)

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Geography & Travel

coral reef

geology

Also known as: organic reef

Written and fact-checked by The Editors of Encyclopaedia Britannica

Last Updated: Mar 24, 2024 • Article History

Great Barrier Reef

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Category: Geography & Travel

Key People:: Charles Darwin; James D. Dana; Alexander Agassiz; Sir John Murray

Related Topics:: atoll; platform reef; cay; barrier reef; fringing reef

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Recent News

Mar. 23, 2024, 4:23 AM ET (The Star)

Lab-bred coral renews hope for reefs

Mar. 13, 2024, 12:17 AM ET (NPR)

Sea cucumbers' eating habits may protect coral reefs against disease: study

coral reef, ridge or hummock formed in shallow ocean areas by algae and the calcareous skeletons of certain coelenterates, of which coral polyps are the most important. A coral reef may grow into a permanent coral island. Often called the “rainforests of the sea,” coral reefs are home to a spectacular variety of organisms. A coral reef is actually a complex of features, only part of which is a living coral or algal framework, although the other associated features result from this live segment. The accumulations of carbonate sand and mud provide a habitat for sea grasses and mangroves and ...(100 of 3327 words)

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