GEOLOGY

Detailed explanation-1: -Because photosynthesis requires sunlight, most reef-building corals live in clear, shallow waters that are penetrated by sunlight.

Detailed explanation-2: -Healthy tropical coral reefs grow horizontally from 1 to 3 cm (0.39 to 1.18 in) per year, and grow vertically anywhere from 1 to 25 cm (0.39 to 9.84 in) per year; however, they grow only at depths shallower than 150 m (490 ft) because of their need for sunlight, and cannot grow above sea level.

Detailed explanation-3: -However, not all corals are found on island coasts in shallow seas. In fact, over half of all known coral species are found in deep, dark waters where temperatures range from 4-12°C (39-54°F). For this reason, we call these corals the “cold-water” or “deepwater” corals. They are found all over the world.

Detailed explanation-4: -Reef corals require clear water so that sunlight can reach their zooxanthellae for photosynthesis. For this reason they are generally found only in waters with small amounts of suspended material, or water of low turbidity and low productivity.