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The Biology of Coral Reef Formation

Coral reefs are often called the "rainforests of the sea" due to their incredible biodiversity, but they are built by tiny animals known as coral polyps. These polyps live in vast colonies and secrete calcium carbonate, the same compound found in limestone and chalk, to form a hard, protective exoskeleton. Over thousands of generations, the accumulation of these exoskeletons builds up the massive structures we recognize as coral reefs.

The growth of coral reefs is dependent on a crucial symbiotic relationship. Living within the tissues of the coral polyps are microscopic algae called zooxanthellae. The algae perform photosynthesis, providing the coral with essential nutrients and energy. In return, the coral polyp provides the algae with a protected environment and the compounds needed for photosynthesis. This partnership dictates the conditions necessary for reef survival: clear, shallow, and warm tropical waters that allow for adequate sunlight.

There are three primary types of coral reefs. Fringing reefs grow near the coastline. Barrier reefs, like Australia's Great Barrier Reef, are separated from the mainland by a wide, deep lagoon. Atolls are circular or oval reefs that grow around a submerged volcanic island. Each of these formations supports a unique and complex ecosystem, making their preservation a global priority.