Large Polyped Stony Corals

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(HERE IS AN ARTICLE BY THE RENOUNED AUTHOR LISTED BELOW I THOUGHT WOULD BE OF SOME INTEREST)

(PART-1)

by Michael Paletta

In the past couple of years LPS corals have lost a little of their luster among the reef-keeping elite with the rising popularity of small polyped stony corals (SPS) like Acropora and Pocillopora. Part of the reason for this change was that SPS corals had just become available, and their brilliant colors and exacting requirements added further to their mystique. But, as many reef-keepers have recently discovered, the brilliant colors of SPS corals often fade; and their sudden bleaching or dying overnight has frustrated many a hobbyist.

Fortunately, the knowledge gained from keeping small polyped stony corals has led to much better husbandry for LPS corals. Since the early days of reef-keeping, many new types of LPS corals are being imported, including Scolymia, Herpolitha, Trachyphyllia and Cynarina. Almost all of the new LPS corals are relatively easy to maintain, with a few even reproducing in captivity, and I'm sure they'll remain a favorite among reef keepers for years to come.

Size Matters

The first and most obvious difference between LPS and SPS corals is the size of the polyps. An SPS coral colony consists of many hundred small coral animals whose polyps are usually only a couple of millimeters in diameter. The entire skeleton is very rigid and only a thin veneer of living tissue actually covers the skeleton. Colonies of SPS corals are usually either branching or encrusting. Corals of this type include Acropora, Montipora, Pocillopora, Stylophora and Seriatophora.

LPS corals, on the other hand, are often composed of only one or a few individual polyps. The tissue of these corals extends out from the skeleton dramatically (sometimes five to six times larger than the hard skeleton itself) and new hobbyists often mistakenly think these corals are soft corals or anemones owing to the polyp extension. The skeleton of these corals looks like a cup or vase when the tissue is removed and the inner portion contains numerous indentations called septo-costae, which divide the colony into segments. Readily available members of this group include corals of the genera Euphyllia, Catalyphyllia, Plerogyra, Lobophyllia, Trachyphyllia, Fungia, and Scolymia.

Large Margin for Error

SPS corals come from the fore reef where the water is extremely clean, light and high in oxygen, and the current is very strong. Conversely, LPS corals predominate in the lagoon and back reef areas where conditions are not always optimum. In these back reef areas the water is often turbid and light levels are often much lower than on the fore reef; the back reef often contains more nutrients as well, due at least in part to the slower flow of water. That LPS corals survive and thrive in these conditions is a large reason why they are often the first corals with which we achieve success. I'm not suggesting that LPS corals should be given less than optimum conditions, but there's a larger margin of error with them.

Lighting

For starters, lighting does not need to be as strong as in a SPS tank. In my opinion, LPS corals do just as well and possibly better under fluorescent lighting than they do under metal halide lighting. In fact, I have seen several LPS corals burn under metal halides, but recover and thrive once they were placed under fluorescent lighting. I personally have a Bubble Coral that is just past its 14th birthday. For the first seven years I kept it under varying types of fluorescent lighting, and it is now under indirect metal halide lighting (indirect meaning it rests in an overhang away from direct metal halide lighting). When it was directly under metal halides, the "bubbles" did not fully expand, looked shriveled in appearance and the coral did not appear to be thriving. Only when placed away from the direct light did the coral achieve its optimum appearance.

Filtration

LPS corals do not demand much filtration. I have kept them in systems utilizing trickle filters where the tanks were full of Caulerpa and microalgae (and high nitrate levels when the algae was removed), and these corals always did fine. Currently my LPS corals are housed in a tank with a Berlin system and also in one utilizing the ecosystem method, and they are doing fine.

Water Movement

One area where these corals are demanding however, is water movement. LPS corals seem to require a moderate current across their bodies to stay in optimum condition. This is not to say that the current should be of the same intensity as waves crashing against the reef, like SPS corals require, rather, they seem to do better with water movement that has moderate strength, like that of water moving about the lagoon. The current should be strong enough to move the polyps about, but not so strong as to cause the polyps to retract or be ripped from the skeleton. The reason that moderate current is so essential is that the polyps of these corals seem to be especially "sticky", and just about everything (food, detritus, fish waste, etc.), seems to adhere to them. If adequate movement does not occur these compounds end up sitting on the coral, causing deterioration.

The LPS that seems least tolerant of low currents is the Torch Coral (Euphyllia glabrescens). I had this coral growing nicely and producing new polyps for two or three years before I had to move it because it was burning its neighbors. The move was only six inches or less so the conditions were almost identical. Unfortunately, soon after the move the coral suddenly perished. Only after analyzing all of the conditions did I realize that the one thing that had changed was water movement; it was inadequate in this new location, which was fatal for this coral. Since then, whenever I move these corals I also adjust the water movement and fortunately, no fatalities have occurred.

Trace Mineral Supplementation

LPS corals also need fewer trace element supplements than SPS corals. Any good general trace element supplement seems to be all that they require in addition to maintaining proper levels of calcium and alkalinity. When I first started keeping these corals I did minimal calcium supplementation through monthly water changes and as a result, these corals did not grow very rapidly, nor did they reproduce. However, since I have gone to the Berlin system with constant calcium supplementation there has been a dramatic increase in the growth of these animals (a threefold increase in the size of the coral skeleton over two years, and a comparable increase in the soft tissue mass as well). Several LPS colonies have begun reproducing as well - Euphyllia colonies have grown and then divided into more colonies; Mushroom Corals (Fungia, sp.) and Elegance colonies have budded off daughter colonies which have grown into new colonies.

In my opinion, all of these events are a result of better calcium management; not only supplementation, but also testing to make sure that the calcium levels in my tank are at or over the desired level of 400 ppm. Also, by using kalkwasser as my calcium supplement the phosphate level in my tanks has decreased as well. Keeping phosphate to a bare minimum is essential for coral growth and it also seems to reduce the tendency for the tissue to pull away from the skeleton.

 

[jhnrb]

Part-2

(CONT. FROM PART-1)

Feeding

One of the controversial questions in keeping these corals is whether to feed them directly or not. With adequate lighting most corals can obtain a significant portion of their nutrition from the zooanxthellae in their tissue; their nutritional requirements are not met completely, however, and they have to obtain some additional nutrition from the surrounding water (Riddle, 1995). These nutrients are primarily obtained from the plankton, bacteria and fish waste that the corals capture in the water. However, our tanks are designed to remove as much suspended material as possible so it may be necessary to feed these corals to keep them in the best possible health. I've been feeding my LPS corals for the last three years with pieces of fish or shrimp as well as baby brine shrimp, and I do feel that it helps them to grow and thrive.

If you do decide to feed these corals, the process is relatively simple. First, you should shut off the current in the tank so that the food is not blown away from the coral. The lights should also be shut off so that the fish will be in their resting places and will not take the food away from the coral. The food should be about the size of a pea, and can come from a number of sources including shrimp, scallop or some type of non-oily white fleshed fish. If frozen, thaw the food to room temperature before placing it near the mouth of the coral. (It doesn't matter which mouth you place it by, since the colony shares its stomach.) The food can be placed with tweezers, a feeding stick or even one's fingers. It's not necessary to place the food directly over the colony's mouth, because the coral will move the food to where it wants. The stickiness of the tentacles will hold onto the food until the animal senses it and then it will be gradually passed into the animal's mouth. This movement is amazingly fast and clearly demonstrates how aggressive these animals can be.

'You want a piece of me?'

The aggressiveness of LPS corals is also seen in its behavior towards other corals. LPS corals burn other corals by extending sweeper tentacles toward any neighboring coral which they perceive to be a threat (Ates, 1989). The biggest offenders of the corals in this regard are the Hammer (Euphyllia ancora), Bubble (Plerogyra sinuosa) and Elegance (Catalphyllia jardinei). These three seem to be particularly sensitive to members of the other genera and sweeper battles between these corals will often extend over fairly large distances.

As a result, care needs to be taken when placing one of these corals, because the sweeper tentacles can be two to three times the length of the normal tentacles. Usually, the best place to set these three corals is toward the bottom third of the aquarium, in moderate currents. This placement keeps them in moderate light and also allows for barriers to be placed between them while retaining the tank's natural look. It's also important to provide natural barriers (i.e., rocks, empty space, etc. - anything but other corals) to minimize this aggression. If these corals don't sense another aggressive coral close to them they will not even produce sweeper tentacles.

Interestingly, corals of the same species or genus can be placed together since they usually won't burn one another. Therefore, two or three different Euphyllia corals can all be placed together in one spot and the entire grouping can be treated as one animal when placing other corals adjacent to it. By the same token, three or four Elegance corals of different colors could all be grouped together without worrying that they'll burn each other.

The aggressiveness of these corals is not limited exclusively to other corals. After having been stung frequently by Euphyllia corals for several years, I now react as if I've been stung by a bee. I denature the sting to break down the toxins and use a steroid cream to reduce the swelling. I strongly recommend the use of aquarium gloves for anyone who wants to avoid getting stung by these corals.

Hammertime

There are well over a dozen LPS corals. However, I'll only discuss here the care and special requirements of the few types that are commonly available and which extend their polyps during the day. The most popular coral is the Hammer Coral (Euphyllia ancora). This coral, along with the other corals of it's genus, range in color from green to brown and often contain patterns with both of these colors. The major difference between the corals in this genus is in their tentacle shape. All of the polyps in these corals arise from a central skeleton which is either tubular shaped or looks like an elongated cone. The tissue itself extends out from, and over the skeleton and may encompass a volume four times as large as the skeleton itself.

(A)sexual healing

To date I have seen this coral reproduce asexually by three different means. The most common means is when the colony simply divides in half and splits into two.

A less common way, which occurs predominantly in Hammer Corals, is when a small bud appears in a dead portion of the skeleton, well below the living tissue. This small bud is a miniature version of the parent colony. Within six months, when conditions are right and it has grown large enough so that there is sufficient dead skeleton between it and the mother colony, this daughter can be broken off. This new colony can then be placed within the reef tank where it will grow into a complete new colony. There has been some conjecture as to whether this bud grows out of the mother colony or is actually a planular larvae that has settled out.

Support for this latter hypothesis comes from the third type of asexual reproduction that I have witnessed in Euphyllia corals. In this type of reproduction, which I first observed at Dick Perrin's Tropicorium, miniature polyps of a large colony of Frogspawn Coral were "ejected" when the coral was gently agitated. These daughters then sealed off and settled to the bottom, where they attached to the substrate. After several weeks they began to excrete a skeleton and a new colony was started. This latter mode of reproduction appeared to produce the most offspring; Dick reported that this colony produced two or three new daughters every day. Unfortunately, he also said that the survival rate was not high because the current in these tanks often moved these daughters onto other corals where they were stung and killed.

Nighttime is the Right Time

Unlike the Euphyllia corals, in which several means of reproduction have been observed, the Bubble Coral has shown little of how it reproduces. This is my favorite LPS, because it was the first coral that I ever bought. It is also the most aptly named of all the corals.

The Bubble Coral (Plerogyra sinuosa), and its close relative the Rice coral (Physogyra lichtensteini), have tentacles that extend during the day in the form of bubbles. This tentacle inflation is thought to be a method of protecting the main body from excessive light. These corals range in color from white to light green depending upon the location from which they are taken, the main body of the animal below the bubbles is often light blue in color.

Unlike the Euphyllia corals, the Bubble Coral needs to be observed at night to really see the sweepers, since they appear only after their bubbles have been deflated. I learned this the hard way and almost lost a Leather Coral. For several weeks after placing a new Leather Coral in the tank I noticed that the polyps on one side of it were not opening even though the rest of the colony seemed to be doing well. I also noticed that this same portion was excreting a lot of slime as well. At the time, my Bubble Coral was relatively small with a three-inch base and bubbles that extended only an inch from the base. During the day when I observed the Bubble Coral it was three inches from the Leather Coral, even when fully extended. I concluded that it couldn't be the Bubble Coral that was causing the irritation. However, until I observed the tank in the middle of the night I didn't realize that once the bubbles deflated, the sweeper tentacles came out and easily extended over to burn the Leather Coral. What was even more amazing was that these sweepers had somehow even gone against a slight current from the opposite direction. Since then I've always used natural barriers to prevent my Bubble Coral from burning anything else.

Michael has written for SeaScope, Aquarium Frontiers and Aquarium Fish Magazine. He has also just published his first book, "The New Marine Aquarium", which is a guide designed to help new hobbyists set up a marine tank. Michael has degrees in biology, psychology and chemistry as well as a M.S. degree in psycho-pharmacology and currently works in the biotechnology field.

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