As you duck beneath the surface, your senses triggers. To your right, a bright orange clown fish defending its anemone home while a moray eel retreats into its cave. As you float in the other direction, you spot giant sea fans coloring the underwater landscape and branching corals beckoning to you. You are scuba diving along one of the many coral reefs scattered throughout the equatorial seas, glimpsing the multitude of life that this largest of living structures supports.

Some of the corals on Quo Vadis Dive Resort s house reef

Your underwater view, however, might not be long lasting if we don’t take care of it better. Seventy percent of coral reefs may be gone in less than 40 years if the present rate of destruction continues. Coral reefs are made predominantly of stony corals and supported by the limestone skeleton they excrete. The rain forest of the sea are home to a quarter of all marine fish species. In addition to the variety of marine life they support, coral reefs are also immensely beneficial to humans, buffeting coastal regions from strong waves and storms, providing millions of people with food and jobs and prompting advances in modern medicine.

How are these incredible structures created? How can a single coral that is only 3 millimeters long (about the size of the word “is” on this page) become a reef that may stretch for miles and weigh hundreds of tons? In our next blog post you’ll learn how coral reefs form, what kind of life they harbor and why scientists say they may largely disappear in the coming century.