STONY CORALS - Large
Polyp Stony and Small-Polyp Stony and SOFT CORALS
The stony corals all produce a hard
skeleton composed of calcium carbonate, a fact reflected in the common name.
Accurate identification of stony coral species may pose difficulties even for
experts, but most of those available in the saltwater aquarium trade are readily
recognizable by genus name. All stony corals require excellent water quality,
and all, except one, require bright, broad spectrum lighting. Tubastrea, the
Orange Polyp Coral, lacks zooxanthellae and must be maintained in a dimly lit
saltwater aquarium. It also requires feeding with a plankton substitute on a
regular basis, and can, therefore, be recommended only to those willing to
expend the extra effort.
Following is a list of stony coral genera
available to saltwater aquarium hobbyists. I have arranged the genera by
families, to facilitate discussion of their requirements, which tend to remain
constant within families.
Click the
 to expand the items below
Stony Coral
- ACROPORIDS AND POCILLOPORIDS
These large families
of stony corals, comprised of the genera Acropora, Montipora,
Anacropora, Astraeopora, Pocillopora, Seriatopora, Stylophora,
Palauastrea, and Madracis, include most of the branching stony coral
genera available in the saltwater aquarium trade.Although exacting in
their requirements, rapid growth rates and the ease with which many
species can be propagated from cuttings have resulted in increasing
popularity.
- PORITIDS
Goniopora, Flowerpot
Coral or Sunflower Coral, is considered difficult to maintain. In
addition, it is easily damaged by careless handling. A related genus,
Alveopora, is almost indistinguishable from Goniopora, and is sometimes
imported.
Several species in the large genus
Porites are imported for the saltwater aquarium these days, with
branching types, such as P cylindrica, being popular. They do not appear
to be as amenable to saltwater aquarium conditions as some other corals,
but this may perhaps be due to collecting and shipping damage, rather
than to any inherent delicacy of the genus.
FUNGIIDS
Heliofungia
actiniformis, Plate Coral, needs a soft, sandy substrate and plenty of
room. It is not really suitable for the typical reef tank, but is
spectacular in a tank designed with its special needs in mind. Fungiids
are the only commonly available corals capable of moving from place to
place.
Herpolitha limax, Slipper Coral or
Hedgehog Coral is a close relative of Heliofungia and needs similar
conditions. Both these species are shallow water corals. Give them
intense light and moderate, not forceful, current.
FAVIIDS
Favia and Favites
are both called Closed Brain Coral. Several kinds are imported. Make
sure any specimen you select is a complete colony, not just a chunk
hacked from a larger specimen. In the latter case, the saltwater
aquarium lifespan of the specimen may be limited. Other faviids that
are available to aquarists include Caulastrea, Goniastrea, Platygyra,
Leptoria, and Montastrea.
TRACHYPHYLLIIDS
Trachyphyllia
geoffreyi, Open Brain Coral, is a hardy and attractive species that is
regularly imported. This coral is a single, large polyp. The skeleton is
in the form of an inverted cone, attached at the apex to a hard
substrate when young, later breaking off to sit in soft sand or mud as
an adult. As a result of this growth form, the coral is easily removed
without damage, which may explain why aquarium specimens do so well.
The related genus Wellsophyllia is also imported for the saltwater
aquarium.
CARYOPHYLLIIDS
Several species of
Euphyllia are available to aquarists, and all make good additions to the
reef tank. All have relatively long tentacles, and must not be placed
close to other invertebrates, which they may sting.
Euphyllia ancora,
Anchor Coral, Hammerhead Coral, Hammer Coral or Ridge Coral, has a
curved extension at the end of each tentacle, giving the appearance of
little hammers or anchors. Very desirable as an aquarium specimen,
this Euphyllia should not be purchased if it hows signs of brown, slimy
material forming at the margins of the colony, an indication that the
coral has been attacked by a protozoan Helicostoma. Sometimes, a two
minute dip in fresh water will eliminate this pest, which apparently
gains a foothold when the coral is damaged by rough handling. Euphyllia
species seem particularly prone to this problem, although other corals
are susceptible, as well.
Euphyllia divisa, Wall Coral, Frogspawn
Coral or Vase Coral, gets its colorful common name from the appearance
of the tentacles. They sport numerous tubercles and white spots,
suggesting a mass of frog's eggs when viewed at a distance. It is
another good saltwater aquarium species, although, again, subject to
protozoan attack.
Torch Coral, Euphyllia glabrescens, looks like a
cluster of ice cream cones attached at their apices, with long tentacles
streaming up from where the ice cream should be, suggesting an Olympic
torch. Catalaphyllia jardiniei, Elegance Coral, is closely related to
Euphyllia. This is one of the most popular, hardy and spectacular stony
corals. Like Trachyphyllia, this species is easy to collect in undamaged
condition. In addition, the polyps can withdraw completely into the
skeleton, where they are adequately protected during transport, and the
coral rarely arrives at its destination in damaged condition. It is
some-what restricted in natural distribution, however, and commands a
premium price. If I were only going to have one stony coral, though,
this would be my choice. Specimens can double in size in six months
time.
Bubble corals are also caryophyllids. Plerogyra sinuosa, Common
Bubble Coral, may be pale blue, brownish or greenish in color, as well
as creamy white. This is a commonly available and popular species.
Beware of damaged specimens, which may not recover in the aquarium.
Physogyra, which looks very similar, is called Pearl Bubble Coral or
Octopus Coral. All caryophylliid corals can be fed small pieces of
shrimp or fish, which will enhance their rate of growth. They may also
eat unwary gobies or other small fish. Do not, 'however, make the
mistake of overfeeding, or feeding too frequently, and bear in mind that
giving no food at all does no harm. All these species rely heavily upon
their zooxanthellae, and can 'survive and grow with this food source
alone.
DENDROPHYLLIDS
urbinaria
turbinata, Chalice Coral, Cup Coral or Wineglass Coral, is so named
because the skeleton is shaped like a goblet with a fat stem by which
the coral is attached to a hard substrate. Thin, brownish tissue covers
the entire surface, so it is important to get a specimen still attached
to a small piece of substrate, not one that has merely been snapped off
above the point of attachment. The large, flowerlike polyps are borne
only on the inside of the "goblet." Turbinaria is interesting in
appearance, and easy to keep. A related, plate-like form is also
imported, and is frequently the color of deli mustard. It also makes an
attractive addition to the saltwater aquarium. Tubastrea, a
non-photosynthetic stony coral imported for its bright orange
coloration, is a dendrophyllid.
OTHER STONY CORALS
Many desirable
species of stony corals are less frequently encountered than those just
discussed. Family Agaricidae (Pavona, Leptoseris. Pachyseris), Family
Oculinidae (Galaxea), Family Pectinidae (Pectinia), Family
Mussidae(Blastomussa, Cynarina, Scolymia, Symphyllia, Lobophyllia),
Family Merulinidae (Hydnophora), are all regularly collected, and one
may even find other genera offered from time to time. There are also a
few species of coelenterates that produce a calcified skeleton that are
not true stony corals, even though they are generally regarded as such
by people in the saltwater aquarium business. Since they are sometimes
imported for the saltwater aquarium, I mention them here. Tubipora is a
stoloniferan soft coral, and is discussed below. Heliopora, Blue Coral,
is frequently seen as a dead skeleton in saltwater aquarium shops, and
is collected because of the pretty blue color. The living coral is
rather drab, and is sometimes found on live rock. This species is
sufficiently different from other coelenterates to warrant placement in
its own order, Coenothecalia, within the Octocorallia. ,Heliopora is
easily confused with Millepora, Fire Coral, a hydrozoan (Class Hydrozoa)
that is found throughout the tropics, and often shows up on live rock
specimens. Contact with this coral can cause a painful rash. Despite
this drawback, it is a good saltwater aquarium species. Also placed in a
separate order (Stylasterina) apart from other hexacorals is the lovely,
delicate Stylaster. The colorful, arborescent colonies are found under
overhangs. As with other non-photosynthetic coelenterates, Stylaster,
though beautiful, is not for beginners.
Soft Coral
OCTOCORALS
There are
two large groups of "soft corals," which differ from the other coelenterates in
that their tentacles are always produced in multiples of eight. Thus, the
collective term used biologists for this group of coelenterates is
"octocorals." If you feel like counting tentacles, you can verify this fact for
yourself. The tentacles of all octocorals also differ in structure from those of
the hexacorals, in that they often have tiny branches along them that impart a
feathery appearance. Biologists divide this group into two subdivisions, and
this is how we will consider them here. Classification of the subgroups is
based upon the structure of the supporting skeleton, which in one group is
stiffened, and in the other, is composed of loose pieces of skeletal material.
GORGONIANS
Soft corals with a
stiffened skeleton are gorgonians, commonly called sea fans and sea
whips. There are a great many species or these, and they come in a wide
variety of colors. Sea whips are branched, like a leafless tree, while
in sea fans the branches are fused together, forming a network or mesh, resembling window
screening. In all cases, tiny polyps are arrayed along the branches; each
gorgonian typically has hundreds of polyps. The color of the polyps, and
sometimes the color of the skeleton, is an indication of the light requirements
for gorgonians. Those in which the polyps are brown or green in color, require
light; those with white, red or yellow polyps, generally prefer shaded
locations. Specimens in which the skeleton is red, orange or yellow are also
generally found in the shade; brownish, blue or purple skeletons typically
belong to species that live out in the open sun. Accurately determining the
species of a particular gorgonian specimen may be quite difficult, but this
should not matter to the aquarist, since all gorgonians have the same basic
requirements. Provide light for those that require it. In all cases, provide
good water movement. Strong currents seem to be very important for these
organisms. With few exceptions, gorgonians collected for the saltwater aquarium originate
in Florida, the Caribbean, or the Gulf of Mexico. The non-photosynthetic species
range from easy to impossible, in terms of their saltwater aquarium care, and should only
be attempted by aquarists who have gained some experience.
ALCYONARIANS
Soft corals
with "flabby" skeletons composed of loose aggregations of spicules are
classified as "alcyonarians." In Florida and the Caribbean gorgonians dominate
shallow water hard bottom habitats; in the Indo-Pacific this ecological niche is
occupied by the alcyonarians. Several of these are commonly imported for the
saltwater aquarium.
LEATHER CORALS
Sarcophyton,
usually called' Leather Mushroom Soft Coral, is among the most suitable of
alcyonarians for a reef tank. In all of the leather corals, the body mass is
brownish or yellowish in color, and the polyps are embedded in this skeletal
mass. Leather corals prefer high light intensities. They often grow almost up to
the surface of the ocean in nature. It is not unusual for the polyps of leather
corals to remain contracted for several days after a change in water conditions,
such as moving them from one saltwater aquarium to the other.
Colt Soft
Coral (Cladiella) is branched like a tree. It is brown in color, with the
"trunk" usually much
lighter than the branches. This lovely species has requirements similar to
Sarcophyton. Other genera of leather corals regularly seen in saltwater aquarium shops
include Litophyton, Lobophytum, and Sinularia. All of the photosynthetic
alcyonarians can be propagated from cuttings taken by various methods, and are
beginning to form the foundation for small marine aquaculture operations all
over the United States.
STOLONIFERANS
Starburst
Soft Coral, also called Green Star Polyps, is frequently misidentified as Organ
Pipe Coral (Tubipora musica), a closely related species with a calcified
skeleton. In Starburst Soft Coral, the skeleton is a rubbery flattened sheet
that encrusts a solid substrate Each polyp resides in a short tube that projects
upward from the basal sheet . The polyps them. selves are generally pale green
with bright green centers, or are an overall lime green color When expanded,
this is a beautiful species. It also,
happily, one of the hardiest and moss durable of reef tank organisms, and can be
highly recommended even to the beginner. Its only light, under
which it will grow and spread. It will even tolerate dim light, but in this
situation it never
looks at its best.
XENIIDS
Several
species of soft corals hold special interest for reef enthusiasts because they
exhibit continuous, pulsing movements. These are collectively referred to as
"pulse polyps," Family Xeniidae, and may be species of either Xenia or Anthelia.
In the former, the columns of the individual polyps are long and thin, and the,
crown of tentacles reminds one of a daisy. They are brownish in color. In
Anthelia, the feathery, white polyps are attached at the base to form a cluster
anchored to a rock or other hard surface. Both Xenia and Anthelia are hardy and
reproduce themselves readily in the saltwater aquarium. Other alcyonarians are imported for the
saltwater aquarium. Most will require the same lighting and water conditions that leather
corals need. One exception is Dendronephyta, which prefers shade, and does not
contain zooxanthellae. It is very challenging to keep and can only be recommended
to advanced aquarists capable of providing for its rigorous requirements,
including live phytoplankton.
AI PTASIA
One coelenterate should be discussed
here because it is frequently a pest. Many authors recommend eliminating the
anemone Aiptasia whenever possible, citing its ability to "nettle'. other
coelenterates. I have heard a number of recommendations for eliminating Aiptasia,
None, alas, are really practical. For example, you can inject each individual
anemone with potassium, sodium, or calcium hydroxide. This will certainly do
them in, but is an extremely tedious undertaking. Pulling or scraping their off
the glass and rocks does no good, since ever a tiny piece of the anemone's basal
disk wil regenerate an entire new individual in a few weeks time. Other
suggestions include intro ducing a Copperband or Raccoon butterflyfish One waits
until all the Aiptasia have been eaten, and then attempts to devise a way to
catch the fish agail before it starts feeding on coral polyps. I am told tha
German aquarists at one time actually set uptanks and deliberately cultivated
abundant Aiptasia for use as "training camps" for immature Copperband
Butterflies destined for duty as Aiptasia removers in the reef tank. The theory
behind this is that the butterflyfish, having learned to feed only on Aiptasia,
will continue this practice once moved from the "training camp" to the front
lines. This seems to me like a lot of trouble for an approach that -may not
always work. Further, if it does not work there is the problem of extracting the
agile butterfly-fish from the carefully arranged reef tank, with all those
crannies and caves. Enthusiasm dims at the prospect of trying to catch any fish,
much less a butterflyfish, under such circumstances. The common, cheap little
Dancing, Shrimp, Rhyncocinetes uritai, will do the job, although you have to
worry about them starting in on your Elegance Coral after the Aiptasia are all
gone. Aiptasia are usually introduced with live rock, and seem to flourish best
in tanks that are too warm, and which have a heavy nutrient load. The best
approach to eliminating them is to create conditions more favorable to desirable
Species such as stony corals, i.e., cool, nutrient-poor water.
One final note about corals. Handle them carefully. They are easy to damage, and
damage can lead to fatal bacterial infections. Make sure you understand the
requirements of stony corals before you attempt to keep them in the saltwater
saltwater aquarium. Learn reef keeping techniques with the easiest species first. Stony
corals are among the most beautiful and fragile of the reef's treasures. If you
decide to keep them in the aquarium, treat them with the care and respect they
deserve. Fortunately, in recent years there have been great strides in captive
propagation of many stony coral species, and the future looks bright for
continued enjoyment of them in hobbyist saltwater aquarium.
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