Faviidae Family of Brain Corals

Phylogeny:  The Faviid Corals are members of the Faviidae Family of Brain Corals and like hydroids, jellyfish and sea anemones are components of Phylum Cnidaria. They are in the Class Anthozoa and the Order Scleractinia of Stony Corals.

Distribution:  The Faviid Corals They are found worldwide in tropical waters and are the most abundant hard corals in the Indo-Pacific and Atlantic. They are found in shallow water, with ample access to sunlight attached to hard substrate such as buoy chains, pilings, rocks, and wreckage in tightly packed colonies with multiple generations building upon the skeletons of previous generations that form coral reefs. Only a few species found at depths up to 100 m (330 feet).  The Faviidae Family has twenty-four genera, the highest number in any Family of hard corals, with more than one hundred individual species, which is second only to the Acroporid Corals for number of species. Faviid Corals are well represented in the Gulf of Mexico; they are, however absent from Mexican coastal waters of the Pacific Ocean. Most “Brain Coral” species are members of this Family.

Morphology:  Faviid Corals are either dome-shaped or flat with a round profile and are characterized by both large corallites with sturdy walls, and thickened septal walls. They have radial symmetry, a hollow digestive cavity, and specialized stinging structures in tentacles surrounding the mouth. Their polyps have a flower-like appearance that produce a hard, calcareous skeleton. Most display a wavy surface. Many species are fluorescent. They can range in size from a golf ball to large branching colonies that can exceed 2.0 m (6 feet 6 inches) in diameter.

Ecosystem Roles:  Faviid Corals are zooxanthellate that have a symbiotic relationship with single-cell dinoflagellates, the zooxanthellae. Zooxanthellae live within certain coral polyps, jellyfish, nudibranchs and sea anemones and produce energy, by means of photosynthesis during daylight hours. This energy is passed along to their hosts, sometimes providing up to 90% of the host’s total energy needs. In return, the host provides nutrients, carbon dioxide, and a secure, sunlit, platform for the zooxanthellae. During periods of chemical or thermal stress the corals can eject the zooxanthellae to reduce metabolic stress, a process known as bleaching, as the coral appear white. Coral bleaching can be an indicator of an unhealthy environment, or a natural response to a short-term condition such as El Niño. The coral can replace the zooxanthellae after the stress has dissipated, or they can acquire a different species of zooxanthellae that are better accommodated to the new environment. In either case, the polyp risks starvation if it is unable to replace the zooxanthellae. Faviid Corals supplement the energy provided by zooxanthellae by using their tentacles to capture amphipods and other plankton from the surrounding water. The tentacles then pass the food to the mouth. Because these polyps are rigid, they are found in areas with moving water, caused by wave action or current, that has an abundance of food. In turn Faviid Corals are preyed upon by crabs, gastropods, fish, crabs, starfish, and polychaete worms.