Sea Stars: Completely marine echinoderms of obviously overall pentaramous symmetry. Live oral side down, feeding on a myriad of sedentary invertebrates and detritus, detrital infauna.

 Numbering in the hundreds on each arm, tube feet can attach to a food object, such as an oyster or mussel, and with relative ease, pry open even the most defensively tightened set of bivalve shells. With even a mere crack of an opening available, the Sea Star can force its slippery stomach into the shell of a mollusk. There it secretes digestive enzymes that rapidly turn the animal's flesh into a puree that the Sea Star promptly absorbs. Momentarily satisfied, the asteroid retracts its stomach, releases its grip, and glides away, leaving an intact set of bivalve shells stripped as if an alien force had cleaned them, leaving no evidence of forced entry. 

    Not for nothing have the invertebrates been called "spineless wonders". Some species of Sea Stars can make fascinating and appropriate aquarium subjects, and many of the Brittle Stars as well, can serve as energetic, if cryptic scavengers in reef systems.

Classification:

Sea Stars and Starfishes make up the Class Asteroidea. Asteroids typically have five arms radiating outward from their central disks where their mouths open toward the bottom. All have podia or tube feet projecting down along the grooves on the undersides of the arms. There is no brain as such, only one or more rings of nerve tissue surrounding the esophagus to lend some coordination to the animal's movements.    

Selection:

Specimens of several genera are commonly offered in the trade, and more unusual species may be special ordered through dealers. What to look for or look out for? The individual in question should be lively, moving and turgid-bodied, with tube feet visible in the case of Sea Stars. A good test is to turn the animal on its back and see if it rights itself. A limp or weak individual is a poor aquarium prospect. Some may eventually recover, but many do not. Most losses of these, and other spiny-skinned animals is subsequent capture and handling trauma.

    Other warning signs are dark or whitish necrotic matter and vacuolations (missing areas). Lost arms are common and will eventually heal over, but it is unwise to buy a specimen that is freshly wounded as infection and rapid decline may follow. Note: not at all rare are "comets", detached single arms that are regenerating new bodies. This is seen as a large arm with a small body and a set of small arms at one end. These are often very good specimens.

    Echinoderms are notable as the only animal phylum with no parasitic members. They are hosts to many parasites themselves, however, particularly copepods and gastropods. You should check a prospective buy for any attached or obvious internal parasitic problems.

Some Fave Groups, Species for Marine Aquarium Use: 

    The most common error in selecting Sea Stars is acquiring species that get too large or are ravenous omnivorous predators. Not only will many species attack various types of reef invertebrates and fishes, they often can't get enough to eat even this way! Unless you are willing to make a special effort to house and feed the larger, predatory species, it is best to star with "reef safe" choices. Among the industry favored species are the very attractive Sand Sifting Star, Archaster typicus, the Little Red Starfish and Orange Marble Starfish (Fromia elegans and Fromia monilis respectively), Blue Starfish (Linckia laevigata), and Purple "Linckia", Tamaria stria. A note of clarification here: these are not necessarily the best suited species for aquarium use. "Regular" Linckias/Linckias in particular are generally short-lived. The genera and species below are our choices for most suitable. 

To: part 2