Providing food and shelter for sea creatures
Coral reefs are spread out over the shallow seas of the world's tropical and subtropical regions. About one quarter of the 500,000 animal species living in the world's oceans inhabit the areas with coral reefs. Even some of the fish species that live in the outer seas use the reefs as places to spawn and raise their fry.
Coral reefs are described as the tropical forests of the ocean, or as ocean oases. Providing shelter and spawning grounds to a wide range of ocean life, coral reefs serve an important role in the marine ecosystem. Living corals have many different colors, such as brown, purple and green, but this color is actually the color of microscopic single-celled algae called zooxanthellae living symbiotically inside the body of the coral.
Corals provide a home for the zooxanthellae and in return, the zooxanthellae, provide oxygen from photosynthesis, and organic matter such as carbohydrates and protein which the corals use as nutrients. In part, the corals excrete this organic matter as a viscous liquid, providing nutrients for tiny creatures, forming a base for the rich marine ecosystem.
There are other important roles played by coral and coral reefs as well. One is the regulation of carbon dioxide levels in the oceans. Carbon dioxide regulation is very essential and without the corals or coral reefs there would be an imbalance of carbon dioxide levels that would severely impact all marine creatures.
Another role is protection from strong ocean currents and high waves. As the name "barrier reef" implies, reefs act as a barrier protecting the shorelines.