Biscayne National Park

These reefs, which are still growing in the offshore Atlantic waters, are built by colonies of tiny polyps which cooperate with microscopic algae living in their tissue to secrete limestone which forms fantastic shapes such as antlers, fans, or brains. Starting on any underwater rock, the mass of dead coral adds up height, until they surface to make up islands, called here the Keys.

The Keys act as tropical barrier islands which shield the Biscayne Bay from beeing battered by ocean waves. Their sheltered side by the Bay, as well as the narrow band of coastal shoreline are lined by the longest mangrove shoreline on the East coast. The mangroves, with their impenetrable prop root system, anchor the shoreline, filter the water, and serve as a shelter for many of the fish species who venture into the marine nursery of the shallow Bay water.