Coral organisms, called polyps, can live on their own, but are primarily associated with the spectacularly diverse limestone communities, or reefs, they construct.
Coral polyps are actually translucent animals. Reefs get their wild hues from the billions of colorful zooxanthellae (ZOH-oh-ZAN-thell-ee) algae they host. When stressed by such things as temperature change or pollution, corals will evict their boarders, causing coral bleaching that can kill the colony if the stress is not mitigated.
Average life span in the wild: Polyp, 2 years to hundreds of years; colony, 5 years to several centuries
Size: Polyp, 0.25 to 12 in (0.63 to 30.5 cm)
Group name: Colony
Did you know? Corals are so sensitive to climatic change that scientists study coral reef fossils to construct highly detailed chronologies of prehistoric climate patterns.
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