Coral and Coral Reef

Estimates of the total ocean floor area covered by coral reefs vary considerably for two reasons: difficulties in estimation due to their submarine location, and differences in deciding what constitutes a coral reef. A conservative estimate would be 235,000 sq mi (597,000 sq km)—only 0.1% of Earth's surface—for reef areas at depths less than 100 ft (30 m). Coral reefs occur in shallow, warm-water locations, primarily below 30° latitude in the western Atlantic and Indo-Pacific regions. Their distribution is strongly influenced by the environmental preferences of the coral animals.