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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.
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
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
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.
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