are reaching the nine-month point of The Coral Forum, and I
have certainly seen my share of questions. But, one type of
question is inevitably going to be asked weekly, if not daily.
This inquiry appears over and over again. The question is: "What
is this coral?"
Sometimes, I am able to ascertain the identity
of the coral to a species level. Usually, I am able to give
a genus designation. Sometimes, I can go no farther than family.
Occasionally, I am struck with a "damifino," as
though spoken profoundly from the wisdom of Ron Shimek. Many
times, I have directly challenged others, who have applied
a species-level designation to a photograph, to explain the
basis upon which they made their taxonomic diagnosis. I do
this for good reason, and hopefully this article will provide
the readers with a beginning point to understand the requirements
and limitations of coral taxonomy in greater detail. I plan
to cover most of the major coral groups in a few installments
of this series - with not too much information to overwhelm,
nor enough to make anyone an expert (nor could I, as I am
hardly an expert in this field, either). It will be enough,
though, so that many of you may begin knowing how to identify
your corals to some level, or at least for you to understand
why I waver, or wave my hands in the air, when confronted
by this frequent request of, "What is this coral?"
Scleractinian corals are some of the easiest
corals to address in terms of taxonomy, but can still be -
and often are - exceedingly difficult to identify. For aquarists
with living corals, identification will, in almost all cases,
only be possible to genus. Even with a dead coral skeleton,
identification to the level of species may be very difficult.
Aquarists (and scientists) often
use well-known references, such as Corals of Australia and
the Indo-Pacific (Veron 1986), to identify their corals. Amazingly,
they will place a species level designation on their coral
at home because it "looks like the one on p. xxx."
Equally as often, they will base their identification on a
coral which someone else has called "species x,"
or from an aquarium website with a coral named "species
y," or the like. Some of the major sources of such designations
are livestock sellers. Almost with reckless abandon, some
very polymorphic and unspeakably cryptic corals have species
names attached like the surname "Smith" to a man
This coral has been incorrectly designated
as Lobophyllia pachysepta.
This is the "real" Lobophyllia
The Montipora capricornis syndrome
and the "Acropora whichspeciesamii" syndrome
Without question, the predilection to add
the species name "capricornis" to any flat,
plating, or whorled, turbinate Montipora is my own
personal favorite. I once spent five days examining a piece
of Montipora, sold to me as M. capricornis,
trying to affix a species name to it. I had six separate taxonomic
reference sources at my disposal, including some of the original
species descriptions for various Montipora species.
I used a dissecting scope, a hand lens, a ruler, a micrometer
and sketches to help me decipher what species I had. Eventually,
I gave up. I could not tell what I had in front of me.
To illustrate this point, I looked
at the first ten pages of photos from a search on google.com
using the search term "Montipora capricornis."
I would question the correct identification of M. capricornis
on all of them, but of thirty or so sites, only two had what
appeared might be the real thing. I then asked members on
reefcentral.com to provide photos of corals they believed
to be M. capricornis. After receiving a bevy of possible
photos, I chose images that were clear enough to see and represented
a spectrum of foliose Montipora species. Without question,
there are some beautiful corals here, and without question
they all display a foliose, plating, or turbinate growth form.
Now for the quiz:
Only one of the images is, to my knowledge,
conclusively Montipora capricornis.
to view the quiz images.
Can you tell which one?
There are also at least seven different
species here, and possibly more. Do you know which ones are
definitely other species?
The answer is that the lumpy pink coral,
15 , is M. capricornis. Of the other images, numbers
1, 3, 9, 26, 27, 32, 34, and 40 look like they could be M.
capricornis, but would require skeletal examination. I
would not consider it likely that any of the others would
be that coral, although normal variations might prove me incorrect.
15 is not necessarily a normal growth form of M. capricornis,
which often more closely resembles the other more turbinate
growth forms. But, this example makes two points at once:
First, that there are many coral species that may closely
resemble one another, that cannot be distinguished by means
of a photo alone, and usually not in a living coral. Second,
that a coral that is well known for "looking a certain
way" may grow in such a manner due to various environmental
and/or physical conditions so that it is completely unrecognizable
by those same normal characteristics.
The second favorite example of mine involves
the species of the genus Acropora. Aquarists seem to
have, more than any other genus of stony coral, an almost
uncanny need to assign a species name to Acropora.
No one seems to care so much when a coral is described as
Favia sp., or even if it's a Favia or a Montastraea
species. But, call it an "Acropora" without
a species designation and you just aren't in the hip "SPS
circle." Almost every commercial site I could visit had
Acropora for sale using species names. Given the Montipora
example above from a pool of perhaps a dozen similar-looking
species, I am sure you can imagine the photos I could exemplify
for a genus with almost four hundred known species, with over
half displaying branching or somewhat "staghorn-like"
morphologies. It took Carden Wallace the better part of her
life to be able to write a 421 page book to speciate this
genus (Wallace 1999), and aquarists all too often simply look
at a picture in a book and mark a coral for sale or in their
tank as, for example, "Acropora yongei."
Despite the excellence of identification
books like the epic "Corals of the World" (Veron
2000), I am sure even Charlie Veron would concur that one
could not look at a photograph in his books and be able to
assign a species to a coral in the vast majority of cases.
Even when one reads about "characteristics," they
are usually found to be of little help. Even when one has
a "key to the species" to read, it is usually of
little help (although we are getting much closer at this point).
Why is this?
There are several reasons:
First, and perhaps foremost, is the variability
of many species. The degree to which variations among similar
corals may overlap taxonomical traits is staggering. For some,
there is almost a continuum of traits with no sharp defining
point on which to say, "This is species x, and this is
species y." On the other hand, some may be so apparent
that a simple glance is all that is required, and you could
say with a great deal of certainty that this is indeed "species
z." Examples of such obvious species would be Heliofungia
actiniformis, Acropora palmata, and Catalaphyllia
Second, and also important, is that the
corals collected for the aquarium trade are very small and
often do not have enough mature growth to be able to accurately
assess defining characteristics. Once placed in an aquarium,
and even if allowed to grow large, the conditions of the aquarium
are so different from the natural world as to provide no guarantee
that such distinguishing features will ever be available;
they may be present, and they may not be present - ever.
Third, and perhaps the defining reason,
is that coral tissue covers the skeleton. In a few cases,
a retracted polyp allows one to identify enough skeletal features
to perhaps be able to identify a coral to species. Far more
often, this doesn't happen. Alternately (and in even fewer
cases), the living polyp can be used to identify a species
where skeletal features may not. An example is with the genus
Euphyllia, where both skeleton and polyp are required
to affix a species name. Also possible is that there is some
amount of tissue loss somewhere on the colony for one to see
enough skeletal features to make an identification. This will
only work for the most obvious cases, and anything more indistinct
will require careful skeletal consideration.
What if I were to tell you that, unless
the coral is unique, very distinct, monotypic (one species
in the genus) or nearly monotypic, or perhaps endemic, you
would not be able to ever - EVER - be able to say with 100%
certainty that the coral you have in your tank belongs to
a specific species? Perhaps not even then!
Here is a general format of what one would
have to do in order to determine the species designation of
a stony coral:
First, become aware of all terminology
used to describe coral skeletal features. If you do not know
what a colline, coenosteum pit, dissepiment, or style is,
stop now. Equally troublesome, descriptive and vague words
are used to describe these features; words that only make
sense to those who have looked at thousands of skeletons.
Phrases like, "thick fleshy walls," and "spongy
columella" dot the literature of coral systematics.
Second, one would have to examine the holotype
and paratypes. The holotype is the original specimen used
to assign a new species, and paratypes are other examples,
in addition to the holotype, that represent the new species.
That is, one has to have an example of a known species in
order to make comparisons. These are usually found in museums
or the personal collections of taxonomists. Ideally, one would
have many examples, physically present, to compare the variability
across a species range and habitat tolerances, including atypical
morphs of the known species, and any that share similar features.
For some corals, it may be possible to go forward without
type specimens, but if you want to be absolutely sure...
Third, one needs the taxonomical references
to describe the species in question. This means not only original
descriptions, but also all revisions and other pertinent works.
For example, for the Caribbean brain coral, Colpophyllia
natans, you would need:
Roos, PJ. 1971. The shallow-water stony corals of the Netherlands
Studies on the fauna of Curacio and other Caribbean islands.
Cairns, SD. 1982. Stony corals (Cnidaria:
Hydrozoa, Scleractinia) of Carrie
Bowe Cay, Belize. Smithsonian Contributions to Marine Science
Zlatarski, VN, and Estalella NM. 1982.
Les Scleractiniaries de Cuba avec
donnes sur les organismes associes. Editions Acad Bulgare
Fenner, DP. 1993. Species distinctions
among several Caribbean stony
corals. Bulletin of Marine Science 53 (3): 1099-1116.
Additionally, you would probably want the
original description from 1772, and supplementary references
such as Humann (1993), Veron (2000), and others. For Indo-Pacific
corals, all volumes of the series "Scleractinia of Eastern
Australia" (Veron 1976, 1977, 1980, 1982, 1984) are almost
mandatory - and yet they contain material that is now outdated
or changed by revisions in Veron (2000). So, both are really
required, as are most of his other works (and there are many
besides his more well-known books). This, of course, is in
addition to any appropriate literature reviews, revisions,
and descriptions by others. I list several revisions under
the genus subheadings for various corals in Aquarium Corals
Some of the references for corals are very
difficult to locate, and library loans aren't a possibility
for many of them. Travel to the holding facility will be required.
I had to fly to four different cities in the US, and one in
Australia, to acquire enough reference material (in addition
to the books and countless papers I already had from local
libraries, photocopies, and loans) to be able to feel even
reasonably safe with the identities of corals in Aquarium
Corals. As it turns out, even that wasn't enough - Doug Fenner,
a coral taxonomist and friend of mine, has pointed out several
probable mistakes in that book.
Next, one could perhaps begin to look at
the coral in question. Using a taxonomic key, one progressively
works through it, bit by bit, looking not at just one part
of the coral specimen, but many, and making sometimes arbitrary
judgements about what is the "average" condition
across the coral. While sometimes things are very clear, sometimes
they are not. Let it also be noted that this is taking place
on a prepared skeleton, and not with a living coral because
the tissue will hide the skeletal features used to identify
it. For some corals, there are relatively few identifying
features. For others, there are many.
For example, let's return to Montipora
Here's what I would do if I were interested
in seeing if a coral I have in my tank is actually a M.
The process begins by carefully breaking
off several pieces of the living coral (without crushing or
damaging the fragile skeleton) and then boiling it and bleaching
it to obtain a cleaned piece of skeleton. I could use a Water
Pik to remove the tissue, but I would be concerned about the
force of the jet of water damaging the skeletal elements on
this particular coral.
With the skeleton in hand, I would separate
the species in question into one of twelve groups that designate
the genus. In this case, it would be the group with "laminar
species without conspicuous coensoteum ridges (Veron 2000)."
Incidentally, this would probably eliminate most of the so-called
"Montipora capricornis-es" from the aquarium-related
sources above. I would then look at Veron (2001) and see that
the characters are described as, "flat plates in tiers
or whorls, sometime with columns, sometimes encrusting or
forming irregularly contorted laminae. Corallites are immersed.
There are no tuberculae or papillae. The coenosteum is coarse.
Color is uniform purple, blue or brown (note: color is often
a poor determinant of identity, and colors can change greatly.
I also note that M. capricornis are mostly found in
lagoons, and this may help explain the color. If they are
in a clear brightly-lit aquarium, the color may not be very
characteristic at all). Their range does include areas where
coral collection takes place, but I have no idea where the
specimen in question came from originally. There are two similar
species (to an expert!) in this group - M. turgescens
and M. florida. There are four species in the group
of "laminar species without conspicuous coensosteum ridges."
I have an unidentified species, and I am not a coral taxonomist
by any means, and so I can't rule any of them out. This is
as far as I can go using Veron (2001).
I do, however, note that the taxonomic
reference is: Veron, JEN (1985). New Scleractinia from Australian
Coral Reefs. Rec Western Australian Mus 12: 147-183. I don't
have this reference. The identification guide given is, "Corals
of Australia and the Indo-Pacific (Veron 1986);" a reference
I do have. Unfortunately, it is little more help. So, I go
a web-based reference database, and find the libraries that
own the requisite reference. I notice that Texas Tech has
it (note to self: pick up this reference), and so I will need
to proceed to acquire that source material. So, without the
M. capricornis reference, I have another option: continue
with a process of elimination of the two or four similar species.
I also note that I do not have the 1967 Nemenzo reference
required for Montipora florida, and so proceed to M.
turgescens. I note that, incidentally, this is not one
of the four species in the "laminar species without conspicuous
coenosteum ridges" category. Sigh. Fortunately, I do
have that reference (Veron and Wallace 1984).
With Veron and Wallace (1984), I am confronted
with ten photomicrographs of corallums of this species that
represent only some of the variations of the 101 (!) type
species that are available from 19 sites only in eastern Australia.
I also note the range of this coral includes Eastern Africa,
the Red Sea, the Indo-Pacific and the central Pacific. So,
there are many more variations likely than what I see here.
I continue my reading.
The following characters for M. turgescens
are from Veron and Wallace (1984). My comments are in parentheses.
are massive, flattened, or hemispherical, or plate-like or
columnar (this means just about any growth form is possible).
The surface may be raised into a pattern of convex subcircular
mounds, 3-12 mm in diameter (a large variation!). Corallites
are uniformly distributed on and between these mounds and
are immersed, with calices 0.7-0.9 mm in diameter. The thecal
rim is usually distinguishable. Septa are tapered and are
in two complete cycles reaching 2/3R and 1/2R deep within
the corallite, where some may have thickened or fused margins.
They are usually short near the corallite rim. They are composed
of regular rows of spines, those of both cycles being of similar
size. Immature corallites are budded in undifferentiated reticulum
and appear as clusters of thin irregular septal spines, similar
to reticulum spinules, but without elaborations. The reticulum
is uniform in structure, spongy, with an outer covering of
highly elaborated spinules.
The present series has very uniform corallite and coenosteal
structures but varies greatly in the degree of development
of the surface mounds (I need to know if there are more series
in possession since this reference). These may be small or
absent on flat or concave surfaces and also vary greatly in
size on convex surfaces, much of this variation being found
in single coralla. In some coralla, they may be small enough
to form the walls of single corallites which consequently
appear to be exsert and similar to the mixed corallites of
M. nodosa and M. australiensis.
Living colonies are uniform in colour, usually brown, cream
Then, affinities are listed to M. nodosa,
M. australiensis, M. mollis, and M. spongodes,
and distinguishing characters are noted. If one is not familiar
with those species, a similar process of examination using
the characters for those corals should be done, as well.
So, knowing that some of this reference
may be dated or incorrect, and that these characters are true
for the species examined from Eastern Australia, and that
variations exist, I can now decide if I can eliminate this
coral from being the specimen in front of me. If I can't eliminate
it based on what I can see or describe, it remains a possibility.
I would then continue with all other possibilities, and eventually
arrive at something that may or may not fit closely with any
one species, and may even ultimately have to admit it "most
closely resembles "Montipora xxxxxxx." In
fact, this is more or less what happened to me when I tried
to identify that coral sold to me as M. capricornis.
Is it any wonder that it might be sort
wrong, to call the Montipora in your
tank Montipora capricornis?
With that in mind, I conclude this installment
of the series. Next month, I will offer some practical solutions
to "getting close" in identifications with living
stony corals in our tanks, and will use some photos of coral
skeletons in my collection to point out key features and identify
specific characters used in taxonomy. The following month,
I will discuss identification in non-stony corals.