Sea Star Biology :
Sea stars are invertebrates belonging to the phylum Echinodermata, which is Latin for “horn skin” or “spikey skin.” Anyone who has ever handled a sea star will attest that the name fits well with these rough-textured animals. Sea stars typically have five arms or rays extending out from a central disk, though some species have up to 20 rays. They are found throughout all the seas and oceans of the world, from the icy poles to the warm, crystalline waters of the equator.
Sea stars have no complex central nervous system: no brain, no head, no eyes. They just have a simple network of nerves that extends down each arm and over the skin. Actually, we know very little about the nervous system of sea stars. But we do know that their skin is highly sensitive to touch and changes in water conditions. This mysterious system also serves sea stars as a means of detecting food. Receptors in the skin cells may register the “scent” or pheromone trail of nearby food items.
Aside from their charming, almost “cute” appearance, the most interesting feature of sea stars is their means of locomotion. Hundreds of pairs of tubelike “feet” line the underside of each ray and are part of a vascular system of pumps and valves. A sea star takes in water through a canal in each arm and hydraulically controls each pair of feet. With plungerlike motions, each pair of feet suctions down to a surface, pulls forward, then releases and grips again. It’s an amazing system that seems almost like thousands of individual units functioning as one, rather than parts of a single organism.
At the center of these tube-clad arms is the mouth, if you can call it a mouth. This organ is more of an opening responsible for digestion, and in many species, it is extendible. It may be ejected from to digest large meals outside the body. Predatory sea stars prey on bivalves, urchins, tubeworms and even other sea stars. Not only do their tube feet allow the sea stars to seemingly glide over even the roughest surfaces, but these powerful appendages can pry apart most bivalves. Tightly gripping the shell of a clam or oyster, a sea star will begin to pull. It has only to pry the shell open a little bit, insert its stomach and digest the living oyster right out of its own shell. Urchins, tubeworms and other large prey items are subdued in the same way.
As if there is no end to the amazing adaptations of the sea stars, these animals have amazing regenerative capabilities. In the mid-1900s, commercial oyster fishermen began finding oyster-eating sea stars in their nets. In an attempt to kill the pesky sea stars, the fishermen would slice the animals in two and toss them back into the ocean. Much to their dismay, the fishermen were only compounding their woes, for the stars quickly grew lost limbs, and halves grew into whole new sea stars. If cut through the center, almost all sea stars species will regenerate a new full body — one sea star essentially becomes two.
Stars in the Home Aquarium:
There are certain conditions that must be met if your sea star is to thrive. Chief among these concerns are water quality and habitat. Sea stars do best when kept in a reef tank. The size of this tank is of minimal concern, unless you plan on housing a large species, such as the crown-of-thorns (Acanthaster planci), or a colony of several smaller individuals. A single palm-sized sea star will thrive in a tank of 20 gallons, though a larger tank is recommended.
Outfit the aquarium as you would any reef tank: rock walls, outcroppings, coral, live rock, caves, nooks, and substrate of crushed coral or fine sand. Keep temperatures between 74 and 80 degrees Fahrenheit, and maintain a stable pH of 8.0 to 8.3. Sea stars are sensitive to spikes in ammonia and nitrates. They can tolerate up to 10 ppm of nitrates, but zero is preferable. Likewise, up to 0.5 ppm of phosphates is acceptable, but the lower the better. Use trickle filters with low to moderate current. Still waters encourage sea stars movement and feeding, while turbid waters tend to make sea stars “hunker down.” They cling to the rocks and move more slowly. Efficient protein skimming and a lot of activated carbon are essential, with 15-percent to 25-percent bi-weekly water changes.
Because their skin is so sensitive to biological stimuli, sea stars tend to fare poorly in tanks heavily populated with fish — the ammonia in fish waste is hazardous to most sea stars. Put only 1 inch of fish per 6 gallons of water in sea stars’ tanks. So, a 60-gallon aquarium could have 10 total inches of fish. Overstocking is perhaps the most common cause of sea star deaths in the aquarium. As long as the tank is healthy and well-filtered, it is possible to keep a good number of nonfish tankmates (shrimp, crabs, clams, snails, etc.). An ornate reef tank sporting a lot of live rock, polyps, stony corals and other such nonfish animals is perhaps the ideal environment for keeping sea stars.
Feed sea stars an initial diet of meaty fare: prawn, lancefish, cockle, mussels, shellfish, Mysis or cut squid. Most starfish (aside from the heavily predatory species, such as the crown-of-thorns) will take vegetable matter, such as boiled spinach, kale or collard greens. Feed every two to three days, or as often as your sea star will accept food. Place a morsel of food beside the sea star. If it is hungry, the sea star will scoot right over the top of the food and consume it. If housed in a tank with pestering fish that are likely to steal the food before the star can claim it, place the food on the tank bottom and place the sea star directly on top of it.
Because sea stars are naturally nocturnal, they like to hide during most of the daylight hours, tucked safely away in a cave or rocky crevasse. Daytime observing can be achieved by offering your sea stars food only during established daytime hours. Despite their lack of a brain, sea stars will quickly “learn” when feeding time is and will venture out of hiding to snag a morsel of fresh meat.
Sea stars do not suffer from many diseases. If water quality deteriorates, however, or if their dietary needs are not met, your sea stars may become afflicted by bacterial infections, which lead to open sores and lesions on the skin. Infected sea stars quickly become sessile and will neither hunt, nor flee from curious fish, such as damsels, which may bite and pick at the star’s wounds. Quarantine afflicted individuals in a hospital tank until they recover, and correct the offending water conditions. If housed in a balanced tank by a competent hobbyist, most sea stars will not suffer a minute of discomfort due to ailment or disease. If a disease or malady does break out in a sea star’s tank, avoid using copper-based medications, as these chemical agents are typically fatal to most sea star species.
Aquarium Sea Stars :
Few marine aquarium invertebrates are as crowd-pleasing as the sea stars of the phylum Echinodermata.
courtesy to : www. fishchannel.com / By Philip A. Purser
Of all the invertebrates a marine hobbyist could keep in his or her tank, few are as crowd-pleasing as the sea stars. These spineless wonders come in a variety of sizes, colors and textures. Sea stars are elegant in their slow-motion treks through the tank and can be almost hypnotic to watch as their tiny suckerlike feet move them from one surface to the next. Brightly colored individuals can add just the right splash of color to an otherwise bland tank, while a few small stars might accent an already thriving and beautiful aquarium.
Yet the variety of sea stars available to the private hobbyist also has a downside. Some stars are peaceful grazers that spend their days quietly munching on algae, while others are relentless predators, silently robbing your tank of all of its crustaceans and invertebrates. So, a little homework is in order before bringing a sea stars home. With a little know-how, the average hobbyist can add a whole new dimension to his or her marine aquarium by including one or more sea stars.
Sea stars can make colorful additions to a marine reef aquarium.
Using Caution with Sea Stars :
A word on sea star husbandry: Some produce toxins that are harmful to humans. These toxins range from mild to severe, depending on the sea star. Use caution with sea stars, and in the case of prickly species whose spines might pierce gloves, consider using sturdy tongs to grasp the animal. Use caution when cleaning the tank, taking care not to brush against your sea star and risk injury.
Choosing Sea Stars :
With so many sea stars to choose from, which one is best? What type will thrive under the conditions of your tank? Which ones eat algae, and which will eat your inverts? Although there are exceptions, a general rule for sea stars is that the smooth-skinned species, such as the blue sea stars (Linckia laevigata), tend to be harmless omnivores, while the rougher, bumpier, spikier varieties are often predators. If you are unsure of an animal in a pet shop’s tank, look at its skin. If it is knobby, bumpy or otherwise heavily textured, leave it at the shop, as it will most likely eat any crustaceans in your tank. Many of the smoother varieties, however, may do a great service to your aquarium by taking care of rampant algae growth. Before making your final decision, research the species you are interested in.
Whatever type you opt for, whether peaceful grazer or relentless predator, always look to color as an indicator of health. When purchasing fish, it is easy to distinguish the lively ones from the sick specimens. But when viewing animals that move at less than a fraction of a mile per hour, vitality may not be so obvious. The brightest, most vibrantly colored individuals are your best bet. Crimson reds, cobalt blues, forest greens and electric yellows are sure signs of optimum health. Avoid animals that look pale or “washed-out,” or those with patches of discoloration. Paleness or blotchiness in sea stars may simply be a side effect of the stress of transport, or it may be a sign of the animal succumbing to a serious bacterial infection — which could cause serious problems if introduced into your aquarium. When viewing several individuals of the same species in a dealer’s tanks, the difference between healthy and unhealthy specimens will be obvious to even the novice aquarist.
Some of the most peaceful varieties of sea stars, such as the blue sea stars (Linckia laevigata) of the Indo-Pacific region, red sea stars (Fromia elegans), orange sea stars (F. monilis) and red-knobbed sea stars (Protoreaster lincki), are obtainable through many pet shops and wholesale marine dealers. These stars are not only hardy and docile but are also some of the most vibrantly colored species available. The blue, red and red-knobbed stars will dine on meaty fare, while the orange sea stars will quietly graze on algae. Augment an orange star’s diet by dropping frozen zucchini squash in front of it. Freezing, then thawing vegetables, such as squash and spinach, causes the cell walls to burst, making the plant very “mushy” and easily digestible by algae-loving sea stars.
Another favorite choice of the invertebrate aquarist is the chocolate chip sea star (Protoreaster nodosus), which is perhaps the most commonly encountered of all sea stars hailing from the warm waters of the Pacific and Indian Oceans. The chocolate chip sea star bears a striking resemblance to its namesake. It is a light tan with rich brown knobs on the central disc and along each of its five arms. This cookielike sea star is generally a harmless omnivore, feeding on meaty foods, as well as the occasional kale or spinach leaf. It will also police much of the algae from the walls of your tank. If housed in a tank with clams, mussels or oysters, however, the chocolate chip star may well dine on them. Reef tanks sporting elaborate invert fauna may also suffer under the appetite of a chocolate chip sea star. Avoid housing these stars with a lot of live rock, hard and soft corals, and mushroom corals. These hardy animals typically fare well in community tanks devoid of predatory or highly aggressive fish. Lionfish and small groupers may thrive with a chocolate chip sea star, but avoid keeping them with triggers, as the star’s “chocolate” knobs will quickly become the triggerfish’s target of harassment. Offer superior filtration and a lot of activated carbon, and your chocolate chip sea stars may thrive for many years, growing to nearly the size of a man’s hand.
Not all marine hobbyists have need of passive species. Some of us enjoy the hostile animals in nature, and might well desire a more predatory sea star. Species hailing from the genera Echinaster, Culcita, Oreaster andAncanthaster are all predatory animals that will thrive in a tank of more hostile fish. Be warned, however, that any other invertebrates in your tank will be eaten by one of these sea stars. House such species with lionfishes, small groupers, moray eels or alone in a species tank.
Perhaps the most well-known of all the aggressive sea stars is the infamous crown-of-thorns (Acanthaster planci). Like its name suggests, this sea star is a multi-rayed species with long, thorny projections covering its body. Some individuals may grow to nearly 24 inches in diameter, with “thorns” as long as 3 inches. This sea star is found from northern Australia to the Philippines and throughout the Indo Pacific seas. In captivity, the crown-of-thorns will feed on virtually any meaty items offered.
If properly housed, these sea stars can make for a living work of art. The most beautiful marine aquarium I ever saw was a brightly illuminated corner tank decorated in dead coral and housing a single blazing red crown-of-thorns. It had the look of a still-life painting, and only the star’s slow movements belied it as a living creature. Be warned, however, that the crown-of-thorns will devour any live rock, coral and any inverts in your tank. Slow-moving fish may also succumb to its appetite.
Given a bit of planning and forethought, a sea star endeavor can add a whole new dimension of beauty and intrigue to the marine aquarium. With the wide variety of species available and the unique attributes of each species, there is a sea star to fit every budget, every hobbyist and just about every tank
Starfish : consideration for the common ( And commonly misunderstood ) varieties
courtesy to : .com / by Anthony Calfo
With progress in natural marine aquarium keeping, increasing numbers of so-called "starfish" successfully reproduce. Applications like deep sand beds and refugium habitats seem to support such success. Some species may become a nuisance by their sheer numbers and prolific nature like Asterina, while others are clearly harmless or helpful by stirring detritus or consuming algae, for example.
This article covers a range of sea stars kept in aquaria, including the deliberate and incidental imports, the decorative and nuisance, or predatory, ones alike. The proper care of sea stars has long been an area of the hobby in need of improvement. It pains me to see fellow aquarists innocently add these animals to variously themed tanks with hardly a thought for what these creatures eat or need to survive. Many folks assume that "starfish" are simply deposit feeders that will somehow find what they need by grazing about the tank. In fact, very few sea stars can live wholly on the incidental matter that grows or collects in aquarium systems. Moreover, very few aquariums are even capable of growing enough food matter, by weight, to sustain even a single Asteroid (more about classes and groups below). In traditional "garden reef keeping," most of us strive to limit nutrients and nuisance algae by underfeeding and the use of skimmers, other grazers (such as Turbo snails, tangs, and urchins) and the cultivation of dominating coralline algae species. This tends to produce "lean" rocks and sand without much soft matter for a sea star to graze upon. In aquariums where suitable food matter does grow for surface-grazing sea stars, insufficient surface area, and hence food, per starfish is oftentimes a limiting factor. Undersized aquaria or overstocked tanks will not produce an adequate supply of potential food matter. The sobering reality about sea stars is that many slowly starve to death within a couple of years, if not mere months, of importation. Making the matter worse, a significant number of collected stars do not survive the importation process to reach a consumer's tank. To be clear, I do not mean to criticize the keeping of sea stars at large. Rather, it is my intent is to acquaint fellow aquarists with some potentially surprising realities about the collection, handling and keeping of these fascinating animals with hope for a more conscientious and responsible use of this group.
The beautiful Blue Linckia sea star is perhaps the best known and most popular and sought after variety. They have rather poor rates of survival with aquarists. Most folks tend to do quite poorly with individuals of this species, exacerbated by sensitivities in shipping and handling. For best success, buy these creatures only on sight and after at least five days of acclimation (stabilization) to a dealer's tank. After that, it is advisable to stock them in mature aquaria with aged live rock and few other grazing fishes or deposit feeding invertebrates. A good rule of thumb is a maximum of one Linckia laevigata per 100 gallons.
Ask yourself when making decisions, particularly about unfamiliar or notorious livestock for your aquarium, "Do I have an adequate understanding of its needs?" Are you likely to succeed in keeping it for its potential natural lifespan? Do you currently have the means (adequate tank size, age and continuous food source) for keeping it, and not merely the hope of improvement, such as a bigger tank, one day? There are other ways to contemplate such purchases; such as, "Is my purchase a conscientious use of this animal?"
Now the definition of what is conscientious use is, to some extent, subjective. But without hiding behind the guise of an infinite amount of "what ifs" or superlative claims and demands, we should be able to agree on the fundamentals, much like the citizens in a commonwealth collectively agree on laws that are "reasonable" to the majority of a given constituency, which all obey for the greater good. Let us simply begin then by addressing that which we could agree is sustainable harvest, from the perspective of empathetic aquarists that regard the life in our tanks as something more than a mere commodity.
At least several species of sea star (including common Protoreaster species), from both tropical and temperate waters, are imported under the common name 'Chocolate Chip Starfish.' They tend to be categorically risky as predators in the long term for tanks with mixed reef invertebrates. They often suffer severe rates of mortality upon importation. It is their low price that perhaps contributes most to the continued popularity of, and tolerance for, these varieties, despite their dubious behavior and suitability for casual keeping in community tanks.
To sum up my position from the start: I believe that an excess of sea stars die between point of collection and final destination of importation, and that too many sea stars successfully imported die within a year of entry to the trade. The reasons for the latter are exacerbated by aquarists who keep these (really, any) creatures casually without: 1) understanding their needs, 2) offering specialized care and 3) adequately target feeding. All of these challenges are sometimes easily overcome with responsible investigation before making a purchase. Start by finding out where exactly does the animal come from on the reef - hard or soft substrates? Some starfishes' feeding preferences are remarkably challenging, as with feather or basket stars filter-feeding on plankton. They may require very specific plankters and even specific types of water flow to have adequate feeding opportunities. Other stars forage around sand, mud and silt for their sustenance and may fare poorly on hard substrates like typical reef aquariums. Other systems with healthy deep sand beds and refugiums that support large worm populations may find certain starfish prosper in concert. Hmmm… let us also not forget the predatory feeding habits of Ophiarachna incrassata, the infamous Green Brittle Star that sits with a fishing pole and drinks beer while listening to country music. Indeed, the feeding habits of "starfish" at large vary widely and it is imperative that aquarists understand their specific animal's needs in advance.
Ophiarachna incrassata, the infamous Green Brittle Star, and a few related kin are the rare exceptions to the otherwise reef-safe and well-behaved Ophiuroid serpent and brittle starfish class. In some tanks O. incrassata will behave for months or even years, while in other tanks they tend to catch and kill motile creatures whenever possible They are active predators, which arch their central disk above their legs to form a trap for fishes and other prey. A lurker pictured here.
Considering the former concern asserted, namely that many sea stars die before reaching consumers, it would be easy to think that we hobbyists have no control here. You do not know the collectors personally, or have a voice in the practices of the airlines transporting the sea life. You do not necessarily know your retailer's sources or have access to a direct line to express your concerns to them. All of this is true. But you do have the ultimate power over all in the trade of any consumer good, be it stereos or starfishes: your buying decision! Our aquarium hobby and trade, like most any act of commerce, obeys currency. If you stop buying it, they will stop selling it… whoever 'they' are. And so, the case I put forth to you is that with so many other hardy and beautiful creatures available, why use any species of dubious value or questionable sustainability?
For example, the sale of live "feeder starfish" as prey for the beautiful Hymenocera Harlequin shrimp is not uncommon. This shrimp has long been believed, at least in popular literature, to feed only on the tube-feet of certain sea stars. As an aside, they have been observed, anecdotally but often, to actually feed on other echinoderms and other parts of these various animals. Within the genusAsterina are one or more species of stars that are prolific in reef aquaria. They usually appear accidentally and have been cultured by aquarists to feed Harlequin shrimp as an alternative to wild-harvested sea stars. Merchants and aquarists may not know of, or may choose to ignore, these other options, though, and rationalize the sacrifice of wild-caught specimens with a claim of light usage, of say - one large wild-caught star per month. The popular imports, however, suffer remarkably high morbidity and mortality just to funnel one healthy live starfish down to the merchant. So we must ask ourselves, how many specimens can be permissibly sacrificed in transit to successfully fill one order: one, two, ten, or more? None need be sacrificed, in my opinion, when Asterina is an easy and available home-grown alternative. Even if such options did not exist, we still would have to practice responsible use of wild-caught species. Losing several dozen collected stars annually to provide one live one per month as a "feeder" is not conscientious from my perspective. In such matters, let us not forget the hard lessons learned by our fellow aquarists in Europe: if you do not adequately police yourself, someone else will do it for you! And it should not take government or legislation to get us to make sensible, if not empathetic, buying decisions like this.
Although sea stars like the aforementioned blue Linckia and this Purple Leiaster(pictured here), have shared reputations for their gross similar appearance, the reality is that their survivability often differs substantially. Because this purple species is far less common in the trade, and therefore more valuable, they tend to get handled better with larger bags and more water in transit. Subsequently, they may enjoy higher rates of successful establishment in captivity. Aquarists should use such insight to strategically select species that are better choices in the long run for both themselves and the hobby.
The following evaluations of sea star species or varieties as "favorable/best of," or "unfavorable/worst of," take into consideration a wide variety of issues. Some potentially excellent aquarium species can make the "worst of" list because of present shipping realities (strategically poor sources of origin - unavoidably extended duration of transit, poorly funded or prepared collection communities, etc.). Putting aside my own reservations about "rules of thumb" or gross generalizations, I offer the following categorizations of the classes of sea stars, which I believe are fair and accurate:
Common and so-called "fancy" Ophiuroids like this banded species are available from Florida. They are hardy, ship well and live long once established with modest but faithful husbandry. Feed small amounts of mixed green and meaty foods several times weekly. A fine scavenger for beginners and newer aquaria that are regularly fed.
Ophiuroids - Serpent Stars: with the exception of basket stars (see overview of Crinoid feather stars below as similarly challenging), the majority of serpent and brittle stars are hardy and suitable for home aquarium life. Many will fare well even in smaller aquariums (under 20 gallons), provided that they are target fed at least weekly. Most are harmless, if not helpful, in reef displays as innocuous bio-turbators (sand-stirrers), eating particulate matter or at least keeping it in motion or suspension for nutrient export processes such as skimmers and mechanical filters. They are the least discriminating and most adaptable feeders of all "starfish." Unlike other popular clean-up creatures (hermit crabs, perhaps most notoriously), Ophiuroids are only a light burden on the bio-load and bio-diversity of the system. Numerous species in this class are suitable for beginners. Species native to tropical Florida waters are highly recommended for aquarists for their utility and ease with which they can be successfully collected and shipped to aquarists in the United States - short transit time, frequent direct flights to distributors, and hardy by nature once established.
Even ornate Ophiuroids tend to be hardy and long-lived once established in reef aquaria. They enjoy rocky habitats and will usually accept a wide variety of foods.
Crinoid - Feather Stars and Sea Lilies: there is very little to discuss here regarding this extremely challenging class of organisms. I won't even pay lip service to the noble charge, "If an advanced aquarist works hard enough and sets up a species-specific system just for [Crinoids], there is a chance of success." Point blank: please do not keep or encourage others to keep these creatures at this time. Why? You may ask. It's a fair question, indeed. Sadly, the overwhelming majority of specimens will perish within weeks or months of collection. They are notoriously delicate and weak shippers. Their dietary needs are poorly understood and difficult, if even possible, to meet in aquarium systems (i.e., steady supplies of enough of the right kind and quantity of plankton, bacteria, etc.). The few specimens out of hundreds that do survive six months or more in captivity simply do not justify the collection of so many others, which die to pave the way for the arrival of each live one. This is one of those groups of reef creatures for whom we must step forward and make a conscientious choice not to support the collection of for casual keeping or impulse purchases. To any aquarist that disagrees with this position, I respectfully ask him to soberly consider the effect that the promotion of keeping such species to the masses does, and to kindly document, if possible, any unique successes of several years or more with Crinoids, rather than simply reporting specimens that took 6, 12 or 18 months before finally starving to death.
Asteroid Sea Stars - classic body "Starfish": without stepping down completely from the anti-Crinoid and anti-Basket Star soapbox, I come to perhaps the most underestimated class of sea stars, the Asteroids. While many aquarists will agree that Ophiuroids are generally hardy and easy to keep, and that Crinoids are difficult to keep, the classic Asteroid "starfish" species are largely mishandled and often suffer very badly for it. Species from this class often carry the erroneous reputation of being good scavengers (like Linckia species) that magically live off of whatever organic film happens to be growing in the aquarium, assuming that beer nuts and salty pretzels are not available to eat instead. Unfortunately, some are so remarkably inexpensive to import for sale that consumers can buy one weak and dying specimen after another with little incentive (beyond ethics) to stop and consider the suitability of the species or source for aquarium use. Alas, this class includes many of the most beautiful sea stars known to man. All is not doom and gloom, however, for keeping Asteroids. Unlike filter-feeding crinoid and basket stars, most of the difficult Asteroid species are not inherently challenging to keep alive. Given an appropriately constructed set of physical parameters in the aquarium, and a healthy import, many Asteroids can be kept with relatively little effort. They do, however, require specific care. Most are carnivorous and target specific prey that may not exist or be adequately produced in aquaria to sustain them (particularly smaller aquaria). Most species in this group are not "reef safe."
A small but steady stream of larger, novelty Asteroid sea stars seems to always trickle into our hobby. Some of these pillow, pincushion and bat stars for example are highly predatory, require uncommon amounts and frequencies of food, and are generally unsuitable for any but the absolute largest home aquaria (over 300 gallons), like this temperate cnidarian predator, Dermasterias imbricata.
It's easy to underestimate the need for small frequent feedings (three to five times weekly) in a sea star's diet. It's even easier to underestimate the need to target feed these creatures at all. We must consider the not-insignificant size/weight of a medium sized "Chocolate Chip," "Red African," or BlueLinckia starfish, for example, which is many times the mass of some popular reef fishes that eat routinely. The size of these animals also causes serious problems without proper quarantine (QT) when a sick or dying specimen crawls into an inaccessible crevice of the rockscape and begins to decay. It's not hard to imagine what a comparable mass, like a 4 oz. package of frozen meat or a large can of food pellets, poured into the tank and left to rot would do to water quality in mere hours. QT is not only for disease control, but also for screening for incidental pests and predators carried in (flatworms or predatory snails, for example) and the simple, controlled acclimation of stressed, newly imported specimens under close supervision.
We should also take some time to consider what is "reef-safe" among new candidates. To anyone with more than just a little experience as an aquarist, the reality of what defines "reef-safe" is better-appreciated. Ultimately, there is no such organism from a wild reef, for display in your reef tank that is purely "reef-safe." Put another way, everything on a reef eats something else on the reef! Thus, the definition of whether a given organism is "safe" or not for your tank truly hinges upon whether or not you personally like or dislike whatever it eats. To illustrate this point, to the aquarist with a dreadful nuisance algae problem, an urchin mowing through the tank eating hair-, macro-, and coralline algae is like is a blessing. To another aquarist without hair algae, simply losing his corallines or desirable macros to the urchin, the grazer may be deemed "not safe."
Asterina sea stars have been accused, unfairly at times, for preying on coral tissue. While some individuals appear to eat some desirable reef invertebrates, the problem may be a simple matter of an opportunistic predator adapting to a change in the available, preferred foods (worms, algae).
Returning to our example of the common, small Asterina species found in some reef tanks, these sea stars in recent years have suffered, unfairly I might add, the reputation of being risky or just plain un-safe in the reef. This is interesting because for many years prior to that, they were not only regarded as harmless, but beneficial! What happened? Did they all change their voter registrations overnight? No, the answer really is quite simple. It also explains why some other "controversial" reef invertebrates have contradictory reputations like Mithrax/Mithraculus crabs. Many such creatures are opportunistic feeders. While they favor one type of prey that is convenient or popular to us, like sand bed worms, brown diatoms or bubble algae, they will adapt to eating other food items following the reduction or absence of a preferred food item. Thus, the reef keeper with a persistent growth of microalgae in a garden reef display will likely have less trouble with misbehaving omnivores than another aquarist with an aggressively skimmed and scrubbed tank that supports little growth of the matter. In a phrase, the hungrier that a so-called "reef-safe" creature gets, the less "reef-safe" that creature becomes. In the case of Asterina, many years ago during the bare-bottomed, nutrient poor Berlin style era of reef keeping, reef husbandry with early protein skimmers and limited nutrient export processes was not as efficient as it is today; diatoms and other nutritious growths grew quickly in our tanks. And Asterina were not considered un-safe by hobbyists.
Summary of Keys to Success with Sea Stars:
Identify the species, needs and suitability of a candidate before purchasing. Know the natural habits and habitat (soft substrates, hard substrates, opportunistic feeder, carnivore, etc.).
Be strategic on selection: avoid impulse purchases, seek Ophiuroids among the most suitable stars. Avoid Crinoids, and resist keeping Asteroids casually or in young or smaller aquaria (less than 1 year old or <100 gallons per sea star).
Quarantine all new acquisitions to screen for possible pests and predators, to acclimate and stabilize newly imported specimens in the confines of close quarters, and to concentrate feeding opportunities to establish a stronger specimen, spare the display from serious risks to water quality in case of a weak specimen dying in the recesses of the rockscape.
Target feed most species several times weekly (smaller, more frequent feedings are always best).
In conclusion, I simply wish to re-emphasize that most starfish we encounter in the aquarium trade are not so opportunistic, if even opportunistic at all, as to be able to survive in aquaria without special attention paid to their feeding and other husbandry requirements. By isolating new acquisitions, addressing special requirements, and not underestimating the needs and merits of keeping starfish in marine aquaria, we can significantly improve rates of survival and success with these fascinating creatures.
If you have any questions about this article, please visit my author forum on Reef Central.
Blake, D. B. 1981. A reassessment of the sea-star orders Valvatida and Spinulosida. - Journal of Natural History 15:375-394.
Colin & Arneson. 1995. Tropical Pacific Invertebrates. Coral Reef Press. Beverly Hills, CA 90210.
Kerstitch, Alex. 1989. Sea of Cortez Marine Invertebrates. Sea Challengers. Monterey, CA 93940.
Sprung, Julian. Invertebrates - A Quick Reference Guide. Ricordea Publishing. Miami, FL U.S.A.
* Special thanks to the Reefkeeping Magazine editorial staff for suggestions and contributions to this article.
Sea Stars Species list :
Sea Stars characteristically have five arms extending from a central disk like a star. In the aquarium they can be fed small pieces of fish, placing the food near or even under the Sea Star. Serpent and Brittle Sea Stars are popular additions to reef aquariums that contain live sand as they constantly stir the bed and provide oxygen to beneficial bacteria.
1-Burgundy Sea Star
Care Level: Moderate
Reef Compatible: Yes
Water Conditions: 72-78° F, dKH 8-12, pH 8.1-8.4, sg 1.023-1.025
Max. Size: 8"
Color Form: Purple, Red
Supplements: Trace Elements
Compatibility: View Chart
Origin: Fiji, Tonga
The Burgundy Sea Star, also known as the Purple Sea Star or Tamarisk Sea Star, is a deep purple to magenta color, and has long cylindrical arms, sometimes having six instead of five.
It prefers a well-lit aquarium with a sandy, coral rubble substrate, and live rock. It will move over the rock searching for small microbes and other bits of common detritus to eat. It may be harmful to clams, sponges, and small anemones. The Burgundy Sea Star is generally solitary.
The Burgundy Sea Star is very intolerant of sudden changes in oxygen levels, salinity and pH of the water, and cannot tolerate copper-based medications. The drip acclimation method is highly recommended for all Sea Stars due to their intolerability to changes in water chemistry. It should never be exposed to air while handling.
In the aquarium, the diet should be supplemented with dried seaweed, and small pieces of clam meat or tablets can be placed under the starfish.
Approximate Purchase Size: 3" to 5"
2-Red Sea Star
Care Level: Moderate
Reef Compatible: Yes
Water Conditions: 72-78° F, dKH 8-12, pH 8.1-8.4, sg 1.023-1.025
Max. Size: 6"
Color Form: Black, Red
Supplements: Iodine, Trace Elements
Compatibility: View Chart
Origin: Fiji, Indonesia, Sri Lanka
The Red Sea Star, or Red Starfish, of the genus Fromiamay be various shades of red. Both the Red and the Red & Black Sea Star have multiple black pores (dots) on its surface. The Red & Black Sea Star has black on the tips of its arms.
It generally lives alone, but if the aquarium is large enough to support more than one, it will tolerate others of its own species. It requires a mature tank with algae and is generally fairly self-sufficient in the aquarium, finding enough micro-organisms and detritus to scavenge if live rock is present. It is diurnal.
The Red Sea Star is very intolerant of sudden changes in oxygen levels, salinity and pH of the water, and cannot tolerate copper-based medications. The drip acclimation method is highly recommended for all Sea Stars due to their intolerability to changes in water chemistry. It should never be exposed to air while handling.
The Red Sea Star is extremely difficult to breed in an aquarium, with no distinguishing characteristics to help differentiate it from its mate.
If there is insufficient algae growth in the aquarium, the diet should be supplemented with flaked foods, and small pieces of fish or mussel.
Approximate Purchase Size: Small; 1-1/2" to 2" Medium; 2" to 3-1/2"