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The Mystery of Goniopora E. Borneman Aquarium Net November 1997

A Death In the Family?

The Mystery of Goniopora

family: Poritidae

genus: Goniopora common species: djiboutiensis, stokesi, lobata, columna, tenuidens, pandoraensis, and others

common names: flowerpot, ball, daisy, false brain

reef friendliness: 1 (1-10)

Ahhh! The allure of the flowerpot coral! Goniopora is certainly one of the most desirable of all corals that we come across in our forays to the local fish store. It is likely one which we have all attempted to keep at some point in our "aquaristic careers," as well. I have personally fielded so many questions about ailing specimens that I developed a macro for my standard response. What is it about this coral that makes its demise almost as certain as death and taxes? It is time to begin a look into the mysterious world of Goniopora.........

Goniopora belongs to the family Poritidae, which includes four genera: Porites, Stylaraea, Goniopora and Alveopora.

At first glance, there seems to be something a bit amiss about this list. The uncommon Stylaraea aside, we are confronted with a group consisting of two fairly similar genera that have really extraordinarily long polyps and one which has some of the smallest polyps in the coral kingdom. For this simple observation, we must begin to question why, as a hobby, we have adopted the term small polyped coral? Certainly groupings based on physical characteristics should account for more? How can there be a simple family with such variance unaccounted in our descriptions. Of course the same can be said for a number of families, including Faviidae, Dendrophyliidae, etc. Perhaps we use this term to describe a genus only? But Turbinaria doesn't fit very well, then! Neither does Pectinia. Well, far be it from me to raise theoretical arguments regarding the relative uselessness of common descriptive lay terminology in hobby taxonomy! But how about that name of flowerpot? Where on Earth did that come from? Are we supposed to imagine that this mass of waving green alien tentacles looks like a container for flowers? Even with flowers in it??!! I don't want to go on a rant or anything....

Excuse me. I got carried away. I won't let it happen again.

If one is look at the taxonomic identifiers of Goniopora, there is a remarkable heterogeneity among species even though these indications are easily masked by the overwhelming beauty of extended flowing polyps.

Colonies of Goniopora form massive round, columnar or branching forms that can grow very large, covering huge tracts of reef. They can rarely be found in encrusting variations, though it is unlikely these will ever be encountered by the hobbyist. A porous skeleton shows corallites with thick walls and 24 septa with porous, pitted and/or spiny margins. The fully retractable living polyps initially present from the skeleton as a ring of extended tentacles. As the day progresses, luxuriant long tentacle-like polyps extend outward up to 40 cm from the skeleton. The result is a fabulous ball of long graceful flowing polyps waving in the current, tipped with 24 tentacles. This taxonomic distinction allows for an easy identification from the only other coral genus which it resembles, Alveopora.

Wood points out that some Goniopora have corallites nearing the size of some species of Porites, but the long polyps of Goniopora make it utterly distinct. Furthermore, most Porites have 12 or fewer septa, if one can has a magnifying lens to count them! The polyps of Goniopora are fully retractable, though healthy specimens will not likely show this capability, remaining partially expanded even at night.

The twenty to forty different true species are found principally on reef slopes, but they may also be found in lagoons and areas of still plankton rich waters. Most occur in areas protected from strong wave action. Coral with long polyps are not normally found in areas of strong wave action as it is not an advantageous characteristic to have in such an environment. The water action would serve only to tangle and tear such appendages, flattening them against the skeleton and substrate where their feeding behavior would be compromised.

Reproduction of this coral is by several means. Polyp balls of small groups of polyps with a tiny calcareous skeleton can form along the margins and undersides of the parent colony, detaching at some time when gravity or manual removal allows it to happen. Polyp balls may even happen in ailing specimens, perhaps akin to the recently discovered Polyp Escape Response of Seriatopora where, contrasting to normal polyp bail out, polyps escape with a bit of their self-decalcified corallite under occasionally normal conditions but usually in response to stress. Sexual reproduction in nature occurs as the separate male and female colonies release gametes as broadcast spawners, the gametes meeting, fusing and forming diploid complete planulae pelagically before settling.

In terms of color, Goniopora can be quite drab or quite stunning. Most specimens seen in the aquarium trade are either brown or green. Some may have a contrasting striped pattern along the tentacles or the coenosteum. However, there are morphs of Goniopora which are purple, pink, cream, copper, lavender, or even pale blue. Exceptionally pretty are those with white or purple contrasting oral disks. However, just because there is an "even-lovelier-than-normal" Goniopora available for an aquarium does NOT mean we should even seriously consider its purchase.


Because Goniopora will, almost without exception, fail to survive in the aquarium.

So again, the question is... Why?

Because....well.....hmmm....good question. It isn't really known; but because the captive care of this coral is so elusive, the majority of the remainder of this article will deal with observations and schools of thought as to why.

The family Poritidae is a logical place to start. Porites, for example, is a huge genus of corals with a less than admirable record of success in home aquaria. The corals, once collected, seem ripe for failure unless provided with usually very bright light and strong water motion. Even so, many an aquarist has failed to keep the lovely Christmas tree worms alive while imbedded in their Porites encased homes. The other common species of Porites usually imported are branching types like Porites cylindrica, and these quite often arrive with areas of recession. This is not necessarily bad, because the very non-aggressive Porites survives in the wild by being able to tolerate areas of tissue and skeletal loss. However, the fateful harbinger of this Poritidae family member in the home aquarium is often initiated when algae begins to overgrow the tissue, causing poor expansion and then a general demise. The commensal burrowing algae, Ostreobium sp., is often a major factor in such deteriorations. Delbeek and Sprung point out that this algae seems to proliferate in the skeleton of Goniopora, as well. Although Ostreobium lives below the tissue in the skeleton of all corals, it is likely that the porous skeletons of the Poritidae family may be a significant factor in its ability to easily gain a foothold, and to begin its boring action further into the skeleton. However, an enigma presents itself here.

Colonies of Porites that come attached to live rock seem unusually hardy. They are resistant to disease, tissue loss, have survived dismal conditions in the collection and transport of the live rock itself, and are generally tolerant in the aquarium to wide varieties of lighting and current regimes.

Maybe the fact that the skeleton has not been broken to allow quick entrance of Ostreobium to the porous inner skeleton has not yet occurred. Does this apply to Goniopora, as well?

Well, perhaps it does based on my own bit of fortunate experience. Like many aquarists, I succumbed early on to the allure and purchase of specimens of Goniopora, only to have them thrive briefly before lapsing into the slow or rapid demise that characterizes their life in captivity. Vowing to never again participate in this seemingly unnecessary loss of marine fauna, I looked forward to a life in the hobby without Goniopora. About three years ago, I received a piece of broken live rock with a bit of coral skeleton imbedded on the rock...seemingly once an encrusting colony and mostly covered with coralline algae, there was no sign of any living polyps from the area. I put this small piece of rock into my ten gallon quarantine reef tank. It remained there for many months without me even casting an eye on it. At one point, I had begun rearranging the rock structure and noticed that this quarter sized area had begun to show a small rings of tentacles poking out of the mostly dead skeletal area. I thought, at the time, how cute! It must be a Favia survivor! I then gave it the benefit of a position where it was receiving the tremendous power (joke) of the two 18" bulbs that lit this small tank and some decent water movement. The colony remained this way, insignificant, though slowly expanding at the margins, retaking some of its well coralline filled skeleton. What a trooper! Because it seemed so trivial at the time, I still paid it little attention until the polyps started showing a little more. I looked carefully at them almost a year ago and thought how similar they were to those of Goniopora. Hardly thinking that possible, I dismissed the thought once again as the little colony continued its growth. Upon moving to Houston, I established the little guy in my Jaubert tank and cemented its rock in place where it would receive, for the first time, excellent lighting with good water flow. Then the miracle occurred. The coral began to expand in a most astounding manner, putting forth long tubular polyps typical of the genus. Calcification has preceded and an inordinately accelerated rate. Perhaps most interesting is the skeletal outshoots which have begun. While no polyp budding is evident, there are sharp calcium spines which have begun to arise from the main skeleton with polyps extending along these spines. This type of growth is quite unusual, and I am curious to see what growth form will result from these protuberances. I also need to take the time to speciate it. The end result is that I have a flourishing Goniopora that has survived dismal initial conditions and has lived for more than three years and is growing rapidly. Is it because this coral was still with its original attachment to substrate. Am I just lucky? Or is it something more?

It has long been speculated that Goniopora fails to thrive because of some nutrient or trace element that is not being provided in captivity. I find it interesting that there has been no elemental "cure" found, despite some very complete trace element supplements currently available. One common element anecdotally said to increase the survival of Goniopora is iron. There are more than a few hobbyists who have claimed to have attained success with this coral by providing regular iron supplements. I have no first hand knowledge as to the veracity of these claims, but I do know of an equal or greater number of hobbyists who have failed to keep Goniopora alive despite regular iron additions. It would appear that this is, therefore, not the answer. At least, not a truly attributable answer. Given the chemical soup that sea water can be, it may be a complex inorganic or organic compound that may never be determined...if that is the missing link at all.

The next factor which may play a role in its success is nutrition. Delbeek and Sprung cite the relative similarity of nitrate and phosphate to the iron example above. It seems that relative abundance or scarcity of either compound have had inconclusive roles in the successes of Goniopora in captivity. Clearly, trying to maintain levels and relative stability most closely like the conditions of their natural habitat are likely to be most beneficial to any coral. In other words, intentionally maintaining high phosphate levels which may poison calcification in order to supply a source of this naturally limiting compound to the polyp or its zooxanthellae may not be a proper solution. The same can be said of nitrate, in that high nitrate levels may cause other imbalances in the relative eutrophic conditions of the water. Before looking at other forms of nutrition in more depth, it is worth looking at some more notable examples.

In his presentation at the Western Marine Conference this past July, Charles Delbeek showed slides taken in the field of very large tracts of Goniopora in water that was thick and blurry with plankton. He cited that this was a very common area where such fields of Goniopora would thrive. He also showed a slide of the now famous 20+ year old Goniopora at the Waikiki Aquarium which receives natural sea water from the surrounding area. These may not be at first imminently notable, but there is another astounding example of success. Morgan Lidster of Inland Aquatics has not only successfully kept Goniopora, but has taken in specimens that were beginning the classic Goniopora demise (covered later) and found that they recovered and then flourished when maintained in his systems. This has been a repeatable situation with a 95% success rate with these corals. These particular systems are run on algae turf scrubbers powered by low planktonic impact Archimedes screw pumps. And, I have a long term Goniopora that was initially in a minimally skimmed system that has begun to grow rapidly now that it is in an unskimmed system.

Dana Riddle provides another piece in the puzzle in his book, The Captive Reef. He notes that Goniopora elicits a feeding response to, among others, the amino acids ornithine, taurine, cysteine, glycine, lycine and phenylalanine. Furthermore, he points out that Goniopora contains up to 35 times the amount of lipid in its tissue as the similarly massive coral, Favia. Goniopora does not produce sweeper tentacles, but is a strongly aggressive coral with potent nematocysts. Its long polyps are adapted to zooplankton capture in areas with reduced currents...generally plankton rich areas. Zooplankton, incidentally, contains fairly significant amounts of heme- (iron) containing elements within their body cavities. Veron notes that because of its aggressive tendencies, other corals are unlikely to be growing near Goniopora, and some colonies may be found to the exclusion of any other coral. Finally, Delbeek and Sprung note that most specimens for the aquarium trade come from turbid lagoon areas. Shimek, in his article "Feed Your Corals, Its the Natural Way," rightly points out the importance and relative necessity of proper coral nutrition.

Summing above the above citations, we see that we have Goniopora that is principally collected from a an area which not only has a generally high plankton count, but is also well adapted to its capture in terms of lack of local competition and physiologic structures. Early experiences with Goniopora were based, at that time, using methods which either filtered out particulate and plankton elements (mechanical filtration devices/wet/dry filters) or actively removed them from the water (foam fractionation devices). Today, the highly successful use of protein skimming in maintaining very high water quality requisite for many other corals may in fact be acting to the detriment of Goniopora. While the ocean has a virtually unlimited capacity to dilute sometimes very high local nutrients by sheer water volume and maintain... well... reef-quality water quality, we have not had that luxury in closed systems. More recently, it has become desirable and possible with some of today's high efficiency skimmers to feed closed systems more often and with larger amounts without degrading water quality. Furthermore, the use of even less violent means of water purification, such as the semi-open Waikiki aquarium, the "Jaubert" style tanks, and ATS systems have also allowed for locally high nutrient/plankton levels without troublesome water quality parameters.

Another misconception that is beginning to be more widely recognized is that while some corals (certainly not all corals) may be able to theoretically meet or exceed their daily nutrient (nitrogen/carbon) budgets through photosynthesis alone, it is unlikely that they do so. This is especially true in captive systems where light levels rarely meet those found on natural reefs. Furthermore, the process of translocation, despite providing a large variety of nitrogen and carbon rich compounds, does not meet the total carbon or nitrogen needs of most corals. They release most of the photosynthetically fixed carbon as mucus. Thus, they turn to feeding to meet the energy needed for growth. So while we do see examples of corals that have "never been fed" that have lived a long time in captivity, it may be absorbed inorganic and organic compounds, bacteria, particulates, etc. that have provided the "food source" despite the fact that we have not been directly offering them food. I suspect that many of the mysterious demises of some corals (e.g Euphyllia, Catalaphyllia, etc.) that depend more on heterotrophy may also be related to today's increasingly sophisticated nutrient export devices and methods. Now that the hobby has advanced to a stage where water quality issues can be more readily addressed and even new hobbyists are able to maintain close to ocean quality water, I am of the opinion that it is no longer necessary to continue to feed tanks with such scarcity out of fear of degrading water quality. Of course, this is provided that sufficient nutrient export abilities are being met and understood. The same can be said, to a degree, with lighting. We now have available a multitude of lighting options that can potentially reach excellent photosynthetic levels of PAR (though still not perfect), and our corals can have the required irradiance to produce photsynthate at a near natural level, in some cases perhaps exceeding natural rates of calcification (Bingman, 1996,1997).

Nonetheless, corals are adapted to their environment quite well through some hundreds of millions of years of evolution. The result is the evolution of very specific and highly complex feeding behaviors and structures which allow for prey capture and nutrient absorption. The adoption of symbiotic algae within their tissues is a trait obviously geared towards increasing successful growth and reproduction. Thus, corals are inherently well suited to two things: feeding and light harvesting. We have spent the better part of a decade addressing the lighting needs of these animals, and continue to do so with a vengeance that light is to many, the tantamount or even sole requirement for their success. We have, in the process, not only neglected nutritional needs, but even gone so far as to make the plankton and whole food elements present (already only present in very low natural levels and offering relatively poor non-natural substitutes in most cases) even less available through our plethora of filtering devices. I think Goniopora makes a strong example in the (admittedly, an as of yet less than complete record) likely need of higher food inputs for many of our organisms...PROVIDED that sufficient excess nutrient export through natural or man-made devices is present. I also feel that there is a fairly large gap in the current literature regarding coral nutrition in terms of natural food elements. I have seen only a handful of papers dealing with gut contents and natural prey selection, indicating that we are still in the infancy of knowing exact nutritional data for our cnidarian friends.

In the classic situation, Goniopora, when introduced to a system as a healthy specimen, shows normal polyp expansion and appears to be thriving. Sometimes within weeks and sometimes with months, the polyps (usually at the base) begin to expand less and less. The recession usually continues across the skeleton until the living tissue dies. This entire process may begin and last for a year or longer, but usually takes place over a period of three to six months. These corals are also highly susceptible to damage from mishandling and such injury often leads to brown jelly or other type infections that can rapidly consume the entire coral. Again, this may be enhanced by the ease of entrance of microorganisms through the porous skeleton.

Given the really atrocious success rate with these corals (which I have given a reef friendliness rating of 1, the lowest rating because of its widespread collection and poor success rate), why are these corals found in virtually every invertebrate carrying fish store across the country? And not occasionally, but with almost certainty of seeing at least several specimens proudly displayed for sale??!! Unfortunately, the reason is either money or a lack of education. The unknowing customer does not know the high probability of failure and because the coral usually does not immediately die, he or she may suspect that it was just "dumb luck," and go right back and try again. Of course, I feel that many local stores not only recognize this fact, but use it to their advantage to gain repeat sales through the repeated deaths of multiple specimens. Sort of a sadistic "planned obsolescence" of living animals, if you will. The other reason is related to demand and collection. the relative abundance of these corals makes them an easy collection species, and the continual demand for them by uninformed aquarists, disreputable stores, and continued losses makes them (tragically) an excellent money maker for all involved. Everyone wins with Goniopora...exc ept, of course, the hobbyist and the coral....

If one decides to purchase a Goniopora at all, which is in my opinion not a good decision until such time as more information comes available regarding their needs, they should be placed in an area of strong lighting and moderate water flow that allows for good passage of particulate matter over the polyps without overly displacing the tentacles. I think feeding these corals is quite important, and the use of a reasonable plankton substitute in tanks without good natural levels is mandated. Again, the article by Ron Shimek entitled "Feed Your Corals, Its the Natural Way" is an excellent place to start. There are other references to plankton composition contained within, and other authors and sources have, in the past, offered through their columns and books, various "recipes" to emulate natural plankton.

I would very much appreciate any feedback from hobbyists who have successfully kept Goniopora alive for an extended period of time, and especially those who had kept Goniopora in unskimmed, ATS, semi-open or high nutrient import/export systems with either good success or failure. I would really like to begin to narrow down the requirements and factors involved in these corals so that their present continued loss can be limited, and also so that someday we can all be treated with a healthy stunning flowerpot coral in all of our tanks.


Atkinson, M.J., B. Carlson, and G.L. Crow. 1995. Coral growth in high-nutrient, low-pH seawater: a case study of corals cultured at the Waikiki Aquarium, Honolulu, Hawaii. Coral Reefs 14: 215-23.

Bingman, Craig. 1997. Presentation: Western Marine Conference, Las Vegas, NV.

Borneman, Eric H. 1997. Still in publication.

Delbeek, J. Charles. 1997. Presentation: Western Marine Conference, Las Vegas, NV.

Delbeek, J. Charles, and Julian Sprung. 1994. The Reef Aquarium.. Ricordea Publishing, Coconut Grove, Florida. 544 pp.

Kramarsky-Winter, E., M. Fine, and Y. Loya. 1997. Coral polyp expulsion. Nature 387:137.

Lagziel, A., J. Erez, B. Lazar, and Z. Dubinsky. 1992. Contribution of zooplankton feeding to the symbiotic association of two hermatypic corals. Proc. Seventh Int'l. Coral Reef Symp. 1: 381.

Lewis, John B. 1977. Suspension feeding in Atlantic Reef Corals and the importance of suspended particulate matter as a food source. Proc. Third Int'l. Coral Reef Symp. pp. 405-408.

Lidster, Morgan, and Eric Burgess. 1997. Inland Aquatics. Personal Communications.

Muscatine, L., and James W Porter. 1977. Reef Corals: Mutualistic symbioses adapted to nutrient poor environments. BioScience 27: 454- 60.

Muscatine, L. 1973. Nutrition of Corals. Biology and Geology of Coral Reefs. 2: 77-115.

Riddle, Dana. 1995. The Captive Reef: A Concise Guide to Reef Aquaria in the Home. Energy Savers Unlimited, Inc. 297 pp.

Ruppert, Edward E., and Robert D. Barnes. 1994. Invertebrate Zoology. Saunders College Publishing, Ft. Worth, Texas. 1056 pp.

Shimek, Ronald L. 1997. Feed your corals. It is the natural way. Aquarium Net. January issue.

Sorokin, Yu I. 1981. Aspects of the biomass, feeding and metabolism of common corals of the Great Barrier Reef, Australia. Proc. Fourth Int'l. Coral Reef Symp. 2: 27-32.

Tanner, J.E. 1992. Experimental analysis of digestive hierarchies in coral assemblages. Proc. Seventh Int'l. Coral Reef Symp. 1: 569-74.

Veron, J.E.N. 1986. Corals of Australia and the Indo-Pacific. University of Hawaii Press, Honolulu, Hawaii. 644 pp.

Wood, Elizabeth M. 1983. Corals of the World. T.F.H. Publications Ltd., NJ. 256 pp.

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Last modified 2006-11-20 04:27