National Geographic : 1971 May
F ANTASTIC CORAL FORESTS reach toward the light on Buck Island Reef. Flippering above a giant brain coral encircled by elkhorn, Susy feasts her eyes on the reef's living colors of green and gold. This underwater metropolis is the patient work of billions of tiny crea tures. Each coral polyp divides into two or three of its kind, thus perpet uating a chain of survival centuries old. The outer layers grow atop a mass 680 of limestone cups-the skeletal re- mains of generations of ancestral polyps. Live polyps contain hordes of micro scopic plants in a mutually beneficial partnership. The coral produces carbon dioxide and other wastes useful to the plants; the plants provide the polyps with oxygen in a convenient arrange ment called symbiosis, from Greek words meaning "living together." * *To learn more about coral reefs, see twin articles on Florida's John Pennekamp Coral Reef State Park by the author and Charles M. Brook field in the January 1962 GEOGRAPHIC.