Final answer:
Corals generally grow within the top 60 meters of the ocean, as this depth provides the sunlight needed by the symbiotic algae within the corals for photosynthesis, which in turn provides necessary nutrients for coral growth.
Step-by-step explanation:
The most suitable depth for coral growth is typically within the upper 60 meters (or about 200 feet) of ocean water, which falls in the photic zone. This is because coral polyps house photosynthetic algae known as zooxanthellae, which require sufficient sunlight for photosynthesis.
The coral and algae engage in a symbiotic relationship, with the algae providing essential nutrients to the corals, which, in most nutrient-poor tropical waters, would not be possible to obtain otherwise. In such shallow waters, coral reefs thrive, supporting high biodiversity and offering protection against shoreline erosion.
Corals in deeper waters, which lack this symbiotic relationship, must rely on capturing prey to meet their energy needs and are not as prevalent as their shallow-water counterparts.