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is a relatively large genus in the family Mussidae,
and consists of twelve species, all of which
can be found in the areas where coral collection
for the aquarium trade occurs, with the exception
of A. maxima. Acanthastrea species
are not easy to distinguish from several other
genera, and even families, of corals. They resemble
other Mussid corals, specifically Micromussa
and Lobophyllia. They also resemble some
species in the family Faviidae which has many
genera and species that can be very difficult
to tell apart.
In general, Mussids are corals characterized
by large corallites with large teeth or lobes
on their septa. The corallites generally have
well developed columellae. In terms of knowing
if a living specimen is a Mussid, it is possible
to see or gently feel the septa for the presence
of these large and often serrated-looking teeth.
If they are not present, it is quite possible
that it is a Faviid.
If the coral is determined to be a Mussid, one
must measure the corallites across the diameter
from wall to wall. Micromussa, which
very much looks like Acanthastrea, has
corallites 8mm or less. Acanthastrea
generally has corallites smaller than Lobophyllia,
and most have corallites between 8-15mm in diameter.
Several species, though, can have larger corallites
and these are the ones most difficult to distinguish
from Lobophyllia and Symphyllia.
is a reason for the above taxonomic distinctions,
in that many aquarists may assume they have
Acanthastrea in their tanks, and do not.
In fact, several of the photos in this ReefSlides
are questionable, and may be other species of
other genera, including the faviid, Caulastrea.
Because these corals have very fleshy polyps,
being able to see the characters that would
determine a positive identity are difficult
to impossible, and even if Acanthastrea
is the correct genus, assigning species in these
living corals is very, very difficult.
some exceptions, Acanthastrea are found
in many locations on the reef, but are often
from shallow water to about 20m in depth, and
are frequently in somewhat protected locations.
Some species, however, can be found much deeper.
They can form colonies that are anywhere from
a few polyps to large hemispherical to encrusting
colonies several meters across, although not
all species are likely to form such large colonies.
the aquarium, as is typical for Mussids, they
are tolerant of diverse conditions and can thrive
in strong or subdued lighting and water flow
regimes. They are voracious predators, and have
strong nocturnal feeding responses. Additionally,
they appear very competitive in their ability
to extrude mesenterial filaments in a coordinated
manner, similar to Hydnophora (as is
seen in the last photo of this slideshow). An
aquarist on Reef Central has provided photos
of this behavior in The
Coral Forum that make her colony
appear related to SpiderMan. Therefore, care
should be excercised when placing these corals
near other sessile organisms that are desired
to remain undigested by aggressive Acanthastrea.
Text by Eric Borneman.
Photos by Reef Central members.
Reefkeeping Magazine Reef Central, LLC-Copyright © 2008