SPS: A Primer
SPS Corals: A Primer
Small-Polyp Stoney Corals are, as a family, more challenging to keep than the majority of LPS corals. SPS is what many keepers aspire to when starting a reef tank. Almost all SPS demand perfect water conditions, high lighting and stronger, pulsing random current. Stability of temperature is vital.
The only physical difference between LPS and SPS is polyp-size. SPS has very tiny polyps, almost unilaterally emerging from small coralites. The majority of LPS have larger, easily seen polyps.
Species of SPS include corals in the classic antler, encrusting, boulder, and plate forms. Nothing says more 'reef' than SPS. Those who remember The Undersea World of Jacques Cousteau TV show, when he visited tropical coral reefs, SPS predominated.
SPS, though a good deal easier to keep than they were in the old days, since most if not all frags are cut from captive mother colonies. SPS are not for beginners or those incapable for keeping them properly. But, I believe forewarned is forearmed, thus this primer. I don't recommend any SPS to any inexperienced keepers.
SPS will avidly feed in the aquarium. A phytoplankton drip to generate zooplankton will enhance the health and form of SPS. Though it's not absolutely necessary to feed photosynthetic SPS, if you wish corals to appear as they do in nature, it's the only way to achieve that.
Now the species.
A family of almost all branched species is Acropora.
A large genus, with over 400 species, so I'll cover a few of the more commonly found. Most all need very high light, like that produced by metal halide bulbs, and strong, random, pulsing current.
It is particularly important that dissolved organics like Nitrate are absent in a SPS tank, and constant natural sea water levels of minerals maintained. You should know that Acropora, as well as most SPS, can release digestive tendrils, called acontia strands, that can dissolve the flesh of nearby corals. Thus, one should space SPS several inches at least so they don't conflict with other corals. All SPS can be considered moderately aggressive because of the filaments.
Long called 'Blue Tip' in the hobby but now available in many other colors is Acropora loripes, a branching species.
Loripes grows into a rather classic form, with strong, slender, bumpy arms with obvious coralites, sometimes in a contrasting color than the arms. It appears rather like an explosion of coral branches, and very well kept, can be quite decorative. Frags are available in several attractive colors.
It does best in the intensely-lit reef aquarium, such as that produced by metal halide bulbs, and strong, pulsing, random currents. One should take considerable time moving the frag to the slope or crest of your reef, to preserve the color and health of this coral. Over time it can grow roughly to the size of a basketball.
Loripes displays small, white polyps in the evening that will capture and consume small creatures, such as Rotifers.
With short arms and almost a perfectly flat growth pattern is the Table Coral, Acropora cytherea. This is one coral which can grow very large, up to 10 feet across, though it'd take a massive tank to allow one to grow that big. Cytherea is native to Hawaiian waters, so a frag is easily found if one searches.
Each arm has incuse coralites, from which the whitish polyps emerge to feed at night. Table does best under halide light, with strong, pulsing, random currents.
Table is commonly found in shades of green and blue, but if moved too quickly to very bright light, will turn to shades of brown.
Table does display small, white feeding polyps at night, and a phytoplankton drip will provide the microorganisms this coral eats. Feeding enhances the size and appearance of this coral.
Table is one of my very favorite SPS.
Available in green, purple, red and blue is Acropora tenuis, found commonly in several South Pacific reefs.
It grows from a rather compact base many, many tapering, round-tipped arms. Over time, in ideal conditions, it can grow rapidly, making a beautiful display. The coralites are numerous and roughly in rows, denoting an avid feeder.
Due to the rich, stunning, colors of this coral you'll see many frags of various color morphs for various prices, the more rich colors costing more. It likes very bright light like all Acropora, but somewhat more moderate, random currents than other species. One should be especially careful and patient moving this coral closer to the lights to preserve the vivid colors and prevent light shock.
The poster child for SPS is the Staghorn Coral, Acropora cervicornus.
Growing in the classic deer antler shape, Staghorn, native to waters around the Gulf of Mexico, is quite endangered. Up to 98 percent of the species has died due to pollution, disease and rising water temperatures due to global warming. Fortunately, Staghorn frags are commercially available, cut from captive mother corals. Because of this, people have hopes the native population, and the species that depend on it, will eventually rebound.
Staghorn can grow very large, with a width up to seven feet across, though such sizes are uncommon in aquariums. It has slender branches that often have off-branches near the tip, with hundreds of coralites on each arm. Staghorn grows in an open form with a wide span of branches. Colors are yellow, orange or shades of brown, but captive populations include purples, greens and blues.
In nature, storms often break off pieces of this coral, and if they land in a place where light, current and food is ideal, will grow into another Staghorn colony. Which means healthy frags are easily found. Like almost all SPS, small, whitish feeding polyps are displayed nightly.
Staghorn, when properly kept, can grow nearly a foot a year, which is quite fast. It likes strong lighting and strong, pulsing, random currents. One must be very, very
slow and careful acclimating to the lights, as this species is prone to bleaching. Once established though, it is quite hardy.
Called 'Cluster Coral' in shops is Acropora millepora.
So named because of the growth pattern of the coral. It grows into a rather compact mass of hefty branches. Its coralites are semi-circular, so the arms look like they have hundreds of upside down 'Cs'. Because of this, the coral arms can look rather fuzzy. It grows into the classic 'ball of coral' form.
Cluster is commonly available in dazzling colors. Like most SPS, it needs very high light and strong, pulsing random currents. NSW levels and temperature must be constantly spot on if one wishes to have success with these reef-building corals.
Colors currently available are many, but the original imports were a creamy yellow. One should take considerable time acclimating Cluster to your proper high light reef to maintain the color of the frag.
All Acropora corals should be very gradually moved over time to the 'crest' of your reef, the upper third, nearest the lights. That is key to keeping the vivid color of the frags, as too quick light acclimation can have the colors change to brown, and in a worse case, bleaching, which is the death of the symbiotic algae that feeds the photosynthetic SPS, can occur.
One should be very patient and careful acclimating your Acropora to your proper high lighting, starting about mid-way up on your reef.
Commonly available and popular is the Bird Nest Coral, Seriapora hystrix.
In the high ligh,t and brisk pulsing random current, aquarium, Bird Nest forms a bush-like, inverted cone form. The arms are thin, branched, and numerous, making the coral look rather like a bird's nest. Lower on the reef in somewhat less light, the arms can grow thicker.
Colors available can include pinks, creams, yellows, purples and reds, the latter rarely.
Due to its need for high light and current, one should place the frag on the slope or crest of your reef. As with all SPS, Bird's Nest should be very slowly and carefully acclimated to your lights, to prevent shock and the possibility of bleaching.
Found in tropical reefs nearly world wide is the Club Finger Coral, Stylopora pistillata.
When this coral breeds, the motile gametes (larvae) travel widely, taking some time before settling and growing, thus is in reefs in both Atlantic and Pacific oceans. This means it's a common sight in better fish stores.
Also called Cat's Paw, Club Finger grows thick, strong branches that are squared-off at the top. This reef-building coral grows into rather a mound of closely-packed branches, and can grow to dinner plate size or larger when properly kept and fed. It is one of the more hardy of the SPS.
Of all SPS, Club Finger is slightly more forgiving as to light and current. Though it is most colorful and grows best in strong, pulsing, random currents on the crest of your reef under halides, one can also site it on the slope where light isn't quite as intense and current is more moderate. Thus, Club Finger is a good SPS for competent beginners to try.
Colors can include an attractive tawny cream, blues and green, though some from Australian waters include specimens with other intense colors of this species.
Like many SPS, Club Finger displays thousands of small, white feeding polyps from its coralites at night. A phytoplankton drip is very helpful in generating tiny life this coral can eat, and feeding will very much enhance the growth and appearance of Club Finger.
Called Cactus Coral in shops are the Pavona species.
The most commonly available is P. varians. The 'varians' is descriptive, since it can be found in branching, encrusting and plate forms. In all of them thin, blade-like coralites are between meandering ridges of the skeleton. Colors include brown, blue, green, red, and most strikingly, multi-colored. This species is common in Hawaiian waters.
When the polyps are displayed in the evenings, this coral can appear very fuzzy. An avid feeder, one should start a phytoplankton drip so this coral can feed on the zooplankton at least a month prior to purchasing the frag.
It likes very bright light and brisk, pulsing currents. It should be gradually moved closer to the lights over time, to preserve the vivid colors of this coral.
Growing into a plate-like form is P. decussata.
With a thin, ridge-like skeleton and available in many colors, though most commonly in red, decussata will attach to live rock. There it forms colonies that can look like a stack of colorful large potato chips.
Most often its frag is placed on the edge of live rock in the upper part of the tank. Growing horizontally, in time you'll have a collection of decussata forming a shelf of coral.
Like the above, coralites are thin from which blade-like polyps emerge from between many, many thin ridges.
Fairly hardy, and thus adaptable somewhat to more moderate light and current, though it does best in strong light and a strong, random, pulsing flow.
With prominent sloping coralites looking like the trunks of tiny elephants is Mycedium elephantotus, the Elephant Nose Coral.
Growing into a plate-like form, Elephant Nose is available in several colors and sometimes available in contrasting colors between the flesh and coralites. In a properly-kept reef tank, it can grow into tiers, folded bowls, or large, flat rounded disks. The shape of the coral is the result of current, light and feeding. Given the latter, Elephant Nose can grow quite large; several feet across, though it will take years to get there, since this species grows moderately slowly.
The coralites in larger specimens can grow more than a half-inch long. The feeding polyps are displayed in the evenings, and for continued health and growth, a live phytoplankton drip will provide the Rotifer population this coral eats.
Elephant Nose should be kept in very bright light, but about midway up your reef since it prefers moderate, pulsing, random currents, however it can adapt to stronger currant and a more prominent placing nearer the lights, if one is quite careful and patient in acclimating it to such conditions.
One of the most unique of the SPS is Elephant Skin, Pachyseris rugosa.
Because of the thin, randomly scattered skeletal ridges, it can resemble the skin of an elephant. In the aquarium in ideal conditions, it can grow quite large; more than a yard across, though it can take several years for it to get there. This coral encrusts live rock, and when moderately grown, can be in a leafy or dish-shaped. Over time, though, it can grow into columns, undulating bowls, tiers and other forms. Colors can include green, blue, cream and grey.
This coral needs intense light, like that from metal halide bulbs, and strong, chaotic, pulsing current. The green-colored specimen I have fluoresces brightly under actinic light. To my knowledge this species either doesn't have or doesn't display feeding polyps. It can, however, capture small life in the slight mucus layer this species possesses. A phytoplankton drip has proven beneficial as Elephant Skin can grow into an attractive, colorful form.
Be sure to get a frag from a captive-raised coral, since wild caught examples often fail in the aquarium.
A moderately challenging species to keep, Elephant Skin is a good coral for experienced keepers to try.
The sole non-photosynthetic SPS coral in this list is Lace Coral, Distichopora species.
What makes this beautiful coral worth keeping is its branching form and color, which can be brilliant red, purple, cream and tan. Found under shaded overhangs in nature, Lace has thick, paw-like arms that are edged by thin feeding tendrils that give this species its common name, as the coral can appear clothed in a translucent lace. The term for such a feeding method is hydnophores. The arms are fragile and easily broken.
Being non-photosynthtic, one must feed this coral to have success with it. Due to my research prior to keeping Lace Coral, I discovered that it most commonly consumes live phytoplankton, so a continual drip is essential. Given moderate, pulsing flow and fed properly, Lace will grow slowly but steadily. Lower lighting is best, since it will prevent algae from forming on this coral. It should be under the edge of partial or full shade in the lowest region in your tank. One should have a phytoplankton drip established at least a month prior to purchase.
In shops the frags don't look like much, but with proper feeding and current, can grow into one of the most beautiful of the SPS. One should inspect a frag closely for health, since a lack of feeding hastens the demise of this coral.
Given proper conditions, Lace is rather easy to keep, so a good choice for those who are prepared to care for it.
Similar to Acropora, but with thicker, strong branches are the Horn Corals, Hydnophora species.
The genus describes the coralites of this coral, as they are are fused together, giving Horn a velvety form. The term for such a feeding form is hydnophores.
Species available include grandis, rigida and exesa. Although all form encrusting mats with vertical arms, grandis is the most decorative, as from a strong trunk, a fan of short arms covered with hydnophores, giving Horn a rather quilted look. The ends of the arms can have a groove, though that may be more typical in other species of Horn. Horn can grow large, several feet across, though it will take some time to get there.
Horn needs very bright light like that from metal halides, strong, pulsing, random currents, and regular feeding. Given them, it can grow quite rapidly, and since it possess short, powerful sweeper tentacles, space corals either on different tiers or a good distance away from Horn. Properly kept, Horn is quite hardy and will grow well, but has been known to fail if placed in conditions not to its liking. Horn is extremely sensitive to dissolved organics like Nitrate, and natural sea water levels of minerals must be spot on, and it is particularly important that the aquarium temperature is steady. Stability is crucial in keeping this coral (all coral actually).
Horn is a Rotifer eater, so a phytoplankton drip is a very good idea to generate the food for success with your Horn Coral. Colors can include blue, florescent green, cream, red, purple, and brown. One should take time and care both in acclimation and placement in your reef, moving the frag slowly but promptly nearer the proper levels of light and current. Established, it is hardy, when kept in proper conditions.
Horn is an interesting, attractive, reef-building coral for experienced keepers that provide proper environs.
Covered in thousands of small, eye-like, roughly circular coralites are the Jewel Corals, Porites species.
Porites grows into dozens of forms, with the jewel-like coralites the only sure way to identify it. It can form boulders, branching, club and finger-like, and more. Colors available include green, blue, yellow, red and purple.
This coral has particularly tiny, whitish polyps, which are displayed at night. If establishing a live phytoplankton drip some weeks prior to purchasing the frag, the Rotifers generated will be happily consumed, and will enhance the color, size and health of the coral.
Species usually available can include Jeweled Toe, which forms an encrusting mat with toe-like arms, and the branching Jeweled Finger, which grows into the classic antler-shaped form. A reef aquarium must be rock solid stable; any variation can damage or kill this coral. Thus, Porites are not for those ill-equipped to keep it.
Porites is peaceful, lacking sweeper tentacles, but can be easily killed by aggressive corals, so place it where it won't conflict. One should take considerable time moving Porites nearer the high lighting to preserve the health and color of the coral.
Jewel Corals need very high light and strong, pulsing current. Stable natural sea water conditions are particularly important with Porites. Given them and regular proper feeding, it will grow well, forming a lovely display.
Called Cauliflower Coral in shops are those of the Genus Pocillopora.
The common name describes it, as the growth pattern rather looks like the head of a piece of cauliflower.
The species usually found are verrucosa, damicornis and meandrina. All are similar, the difference being the shape and size of the skeletal ridges. This coral is widespread and is found on reefs from India to Mexico, meaning frags or it, in many, many different colors, are easily found.
Cauliflower grows into a roughly circular form if surrounded by low walls of live rock. It'll grow long and random on the exposed crest of your reef. Over time, small versions of itself can detach and form new colonies.
The coral needs strong, pulsing, chaotic currents, and frags often fail if you don't give it to them. Though it looks and grows best in the very high light generated by metal halides, Cauliflower can adapt to slightly lower light, like that from a bank of T5 bulbs. But remember, this coral must have strong, random currents. Take considerable time adapting this coral to your lighting.
The mass of ridges are surrounded by raised coralites, adding to the common name. Like most SPS, whitish polyps that are in this case larger than those fhan most, are displayed at night. This coral does feed on Rotifers and phytoplankton, so constant drip of the latter will provide the proper numbers of Rotifers to keep this, all corals and clams actually, in top condition.
Though moderately challenging to keep, a beautiful stoney coral for a hobbyist to try.
A most challenging SPS to keep are the Lettuce Corals, Pectinia species.
What makes these corals harder to keep depends purely on how the frag was kept before purchase. Lettuce is found in nature from the crest of the reef with strong, chaotic currents, down to 50 feet, where light and current are more moderate. Thus, the precise level of light and current must be known before you buy a frag of this coral. Some will prefer lower light and current, some very high light and strong, random, pulsing currents. Make sure you know how the frag was kept, so you can replicate it in your reef.
Species available include the plate-like P. lactuca, which goes under the common name as Frilly Lettuce, Antler Lettuce P. alcicornis, and the encrusting Palm Lettuce, P. peonia.
Lactuca forms a mat with large ridges that continue to grow over time, giving the coral a 'frilly' look. Alcicornis grows into an elk horn form, and Palm produces strong, feathered arms from a rather compact encrusting base. All are available in pinkish, cream, and brown, with contrasting colored arms. Most Pectinia fluoresce in shades of green or blue under halide light.
Pectinia corals display nearly invisible feeding polyps in the evening, and I've found feeding them via phytoplankton drip very helpful in maintaining the health of this coral.
A challenging coral to keep, the Pectinia species, but once established, can thrive when kept properly kept.
Very popular is the Velvet Coral, Montipora digitata.
Digitata can form boulders, encrusting mats, slab-like plates, and even delicate branching forms. The variation is such that almost any shape or color can be found in shops. Common colors are vivid shades of purple, blue, red and green.
The common name describes the feeding polyps displayed at night, since they are quite small and numerous, giving the coral a velvety look. I've found them to consume small life in the evenings, so a phytoplankton drip is helpful in providing it.
Velvet likes strong, pulsing, random currents and bright light, but care must be exercised moving the frag to the latter.
Though fairly difficult to keep, with the encrusting and boulder forms slightly hardier, Velvet is an attractive addition to the reef.
Our last coral is one of the most challenging, Ruffled Coral, Merulina scabricula.
Ruffled can grow into vertical plates, tiered ridges, and rounded mats, All, over time, will grow feathered branches upward. Very common in nature, it is found in areas of high turbidity in shallow water, meaning it needs brisk, chaotic currents that pulse in the aquarium. High dissolved Oxygen is particularly important, and it cannot drop below 8 mg/l at any time, day or night, for success with this coral. Lighting should be strong, and halide light is recommended.
The coral has cross-hatched ridges across the skeleton, giving it the common name. Small feeding polyps are displayed at night, so a phytoplankton drip will develop the rich level of zooplankton this coral experiences in nature.
Colors include florescent green, blue, pink, cream and purple, often with contrasting colors on the ridges. It is a lovely display under halide light.
In a scale of difficulty, Ruffled Coral is a 10, but is by no means impossible to keep, thus is a good species for experienced keepers that can keep it properly. Established, it is quite hardy and attractive.
So ends the SPS primer. Though more challenging to keep than LPS or soft corals, success with SPS gives one a sense of accomplishment. I have hopes this primer encourages more to try their hand at SPS.
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