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The Architecture of Coral Reefs

Coral reefs are often called the "rainforests of the sea" due to their incredible biodiversity. These complex underwater structures are built by tiny animals known as coral polyps. Coral polyps live in large colonies and thrive in warm, shallow, and clear tropical waters. They have a symbiotic relationship with microscopic algae called zooxanthellae, which live within the coral's tissues. The algae provide the coral with food through photosynthesis, and in return, the coral provides the algae with a protected environment.

The formation of a coral reef is a very gradual process that takes place over thousands or even millions of years. Each coral polyp secretes a hard exoskeleton made of calcium carbonate. When a polyp dies, its skeleton remains, and new polyps grow on top of it. Over countless generations, the accumulation of these skeletons builds up the massive structure of the reef. There are three main types of coral reefs: fringing reefs, which grow close to the shore; barrier reefs, which are separated from the shore by a lagoon; and atolls, which are ring-shaped reefs that enclose a lagoon.

Coral reefs are critically important ecosystems. They support about 25 percent of all marine species, providing them with food and shelter. They also protect coastlines from erosion and storm damage by absorbing wave energy. Unfortunately, these vital habitats are under threat from a variety of factors, including rising ocean temperatures, which can cause coral bleaching—a phenomenon where corals expel their symbiotic algae and turn white. Pollution and overfishing also pose significant dangers to the survival of coral reefs worldwide.