These primitive, unassuming animals are the mighty master builders of the reefs. The creation of one reef requires the team effort of billions of individuals. Each extracts building material calcium from the sea and uses it to make itself a protective tube-shaped skeleton. Together, hundreds of these skeletons make a coral. Many corals growing side by side and one on top of another, form a reef.
Corals are very particular about where they build reefs.
Such conditions exist all along the Florida Keys in and south of Biscayne and in the Caribbean, as well as in some other tropical oceans. An Undersea Metropolis - The reefs are the cities of the sea. In and around them lives a huge and diverse population of fish and other marine creatures. Every hole, every crack is a home for something. Some inhabitants like the Christmas tree worm, even live anchored to the coral.