What Are Coral Reefs?
Author: Marc Lallanilla
October 8, 2013
There are hundreds of different species of coral, according to the Coral Reef Alliance (CORAL), a nonprofit environmental group. Coral have a dazzling array of shapes and colors, from round, folded brain corals that resemble a human brain to tall, elegant sea whips and sea fans that look like intricate, vibrantly colored trees or plants. [Photos: Stunning New Coral Species of Polynesia]
Corals belong to the phylum Cnidaria (pronounced ni-DAR-ee-uh), a group that includes jellyfish, anemones, Portuguese man o' war and other marine animals. Though each individual animal is referred to as a polyp, corals are often described as a colony of thousands of polyps.
Corals feed in two different ways: Some species are able to catch small sea life like fish and plankton by using the stinging tentacles on the outer edges of their bodies. Most corals, however, have a symbiotic (mutually rewarding) relationship with algae called zooxanthellae (pronounced zo-zan-THEL-ee), according to the U.S. Environmental Protection Agency (EPA).
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