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Many types of brain corals are common on coral reefs worldwide. They are also quite common in the aquarium trade. The brain corals are typically massive to submassive corals that are also known as "head" corals. In common descriptions, "closed brain" refers to species whose shape is rounded or almost round, while "flat" or "open" brain refers to species with a flat or "open" configuration. There are many species of what are commonly called closed brain corals. Most have rounded or twisted, massive heads with either worm-like channels or round "craters" that give them a characteristic appearance that resembles a brain. The open brain corals also have these channels, but the skeletal shape is more flattened, and the coral tissue appears heavier and more "meaty" in appearance. In many cases, it may be difficult to ascertain with any degree of accuracy which species is for sale because of typically small specimen sizes and number of similar-looking species that exist. There is also a certain amount of variability within members of the same species. Feeding brain corals is possible when their tentacles are extended, though this is not necessary in all cases. Tentacles normally appear at night and these are clear in color. They are found ringing the inner corallite walls or along the channels. These corals can grow to massive sizes in the wild - often meters across. However, they grow slowly and tend to produce dense skeletons. Brain corals usually adapt well to captive conditions if given proper care, and are generally an attractive and hardy group recommended to the hobbyist. They are not available commonly as captive grown species, and they require some collateral reef damage to collect.

The closed brain corals are typically flattened to head shaped and have large, heavy polyps. This is the reason given for one of their common names of "meat" coral. The polyps are sometimes separated from each other and sometimes connected by sinuous channels called meanders. The majority of closed brain corals are species of the very common genus, Lobophyllia. Their colors can be quite striking. Symphyllia species are more easily recognized by usually having a prominent groove that runs along the top of the meandering corallite walls. Some species of Symphyllia can be very "open" in their polyp and skeletal configuration, while others can closely resemble species of Lobophyllia. Most colonies are broken from larger colonies which can be several meters across. Species identification of the brain corals is hardly possible without skeletal analysis. The corals from all three genera are quite hardy. They are found in diverse locations, but seem to tolerate broad variances in lighting and water flow. Colonies feed at night, although the presence of food in the water may cause a daytime feeding response, as well. They are all hermatypic and zooxanthellate.

Maze corals are so-called because their polyps form in long meandering valleys that give the appearance of a labyrinth or maze. They are flattened to head-shaped, and are also frequently considered "closed" brain corals. The members of this group are known simply as "brain corals" in the Caribbean, but consist of the genera Diploria spp. and Colpophyllia sp.

Polyps can be distinguished by the series of mouths that can be seen along the centers of the valleys. Polyps extend at night and sweeper tentacles are very common. They should be placed on the reef framework with good water flow and lighting all around. They are all hermatypic and zooxanthellate.

While certain species of Symphyllia may (and should) be considered "open brain" corals, the classic open brain coral refers to the genus Trachyphyllia. This is a mostly free-living coral that is often not found in association with the coral reef framework. It is found buried in soft sediments or nearby to reef framework. There are variations that are referred to as Trachyphyllia radiata and Wellsophyllia radiata, that have meanders that are fused all the way up to the center. These names are incorrect, however, and there is only one species currently recognized. Open brain corals can adopt a very open, figure-8 type formation, or they may be more folded. Often, it may be difficult to tell the difference in small colonies of Lobophyllia and Symphyllia, and they are frequently identified as "open brain" corals.

Text by Eric Borneman.
Photos by Reef Central members.
Many thanks to John Love (Rock Anemone) for his assistance with this project.

Reefkeeping Magazine™ Reef Central, LLC-Copyright © 2008