Oysters are shelled, filter-feeding animals related to clams and scallops. Microscopic young, called spat, float in the water column until they grow and settle on a hard substrate where they cement themselves in clumps. Clumps of oysters, sometimes called reefs or beds, provide invaluable shelter for small crabs, shrimp, marine worms, snails and other invertebrates (animals without backbones).
At high tide, fish such as spotted sea trout, red drum and snook patrol these beds looking for food, small animals that are hidden amongst the shells. At low tide, the reef serves as a buffet for wading birds including the american oystercatcher. Oyster beds also serve as excellent substrate for mangrove seedlings (called propagules) to take root.