Hard Corals on the Belize Reef
These showy colonial animals are the most noticeable component of the Belize Barrier Reef. Their forms range from large tree like structures and large boulder structures to small fragile looking forms.
Hard corals are colonial animals, each small individual has its own living chamber and feeding tentacles, but digested food is shared throughout the colony by connecting tissues. As each individual builds its own calcium carbonate living chamber, its chamber is joined to adjacent ones to make a rigid solid mass, rather like a large apartment complex. Sometimes the individual living chamber is easily visible, at other times the naked eye cannot easily distinguish them.
These corals are usually found in clear warm waters and are primarily night feeders. Each individual coral (animal) extends its tentacles into the water to capture and pull small food particles into its digestive system. While these corals may look lifeless during the day, at night the colony “blooms” with thousands of small polyps waving in the waters seeking passing planktons for food.
Although some of the hard corals form very large structures, only the outermost layer is alive. Growth is in an upward and outward direction with individuals slowly building the walls of their living chambers higher and depositing more floor underneath them, leaving the interior of the coral a lifeless mass of calcium carbonate.
Grazing fish, algae, sponges, urchins, storms and mud in the water affect the living corals. Some fish have teeth designed to rasp away at the hard coral, feeding on the coral animal. Storms can break off or move corals and bury them in sediment. Large amounts of mud brought into the area can cover the coral animal and prevent them from feeding or extracting oxygen from the water. For the most part, after storm damage, a coral colony can recover.
Photograph courtesy Allan Hines
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