The waving forests of sea whips and sea fans are a uniquely Caribbean feature, and are not found on reefs in the Pacific and Indian Oceans. Similar to reef-building corals, they have zooxanthellae within their tissue. The rigidity of coral reefs helps protect the shoreline from destructive tropical storm waves. Reefs provide habitats for hundreds of species of marine organisms including commercially important finfish and shellfish. Ecologically speaking, coral reefs are diverse places, containing 22 of the 23 animal phyla found on the planet.
Symbiotic relationships are common and add to the complexity of species interactions.
The deterioration of the marine environment in the Keys is no longer a matter of debate. There is a decline of healthy corals, an invasion by algae into seagrass beds and reefs, a decline in certain fisheries, an increase of coral diseases and coral bleaching. In Florida Bay, reduced freshwater flow has resulted in an increase in plankton blooms, sponge and seagrass die-offs, and fish kills. Storms, heat waves and other natural events can be blamed for some of the deterioration, but the activities of people are also responsible. Over 80,000 people reside in the Keys full time.