Each coral reef is a unique and highly productive ecosystem. A reef can support thousands of different species from almost every known group of living things. All of these species depend on one another and the coral itself for their survival. As in all ecosystems on Earth, organisms that live there maintain a delicate biological balance of competition and cooperation.
Reefs are busy centers of activity in an otherwise scantily populated ocean landscape. Their nooks and crannies provide hiding places, nurseries, and spawning grounds for many types of sea organisms. Each group of organisms that moves into a coral reef helps attract and maintain other kinds of living things. The mature reef hosts hundreds of species in a bright display of color and activity.
Coral reefs are small but invaluable pieces of the Earth’s ecosystem. Reefs are more sensitive to pollution and other changes in environment than most other ecosystems are and are the first to reflect damage. Scientists watch them closely for signs of harm, knowing that what happens to coral reefs may eventually happen to other ecosystems.