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Aquarium Sea Stars

Few marine aquarium invertebrates are as crowd-pleasing as the sea stars of the phylum Echinodermata.

By Philip A. Purser

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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 and Ancanthaster 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. Previous Page>>

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