Not sand-sifting stars. These are just too efficient at cleaning up (eating) so much interstitial fauna (between substrate grain biota). Should really only be stocked (if used at all) at one per hundred, two gallons.

     Shown, one of a few commonly employed sand sifting Seastars, Archaster typicus

Asterinas, no! Asterinas, yes. This delightful genus hosts a myriad of small; at times colorful (blues, greens, reds…) species of small stars. They feed largely on algal films, but may disturb other encrusting life if allowed to reproduce to high density (keep the herd thinned).

Asteroids to give a pass are many. Too many of those offered in the trade are altogether unsuitable… getting too big, shipping poorly, just dying easily most the time… And some are predaceous. Some notable examples to pass up: At right, the genus Linckia (here L. laevigata, but the whole genus is bunk)… dismal survival history.

Below: The popular, but short-lived Chocolate Chip Star, Protoreastor nodosus, lastly, the African or Horned Seastar, P. lincki, predator of other sessile invertebrates.

Ophiothela danae on an arborose sponge in Malaysia’s Palau Redang at right.

Below, Ophiothrix suensonii, a delightful common Indo-Pacific hitchhiker; here on a unifacial pinkish sponge.

A freebie on atop a mushroom at the 2008 Interzoo show. You need to keep an eye on the individuals and population of Ophiuroids in your system to assure they’re not getting too large or predaceous.

A former darling, but blatant fish eater, the Green (Deathstar!), Ophiarachna incrassata. Becomes too large for our consideration anyway.

Below, a frequent offering, Ophiothrix rubicundum or Ophioderma squamossimum in the wild.  Oh, and a big pile of them at a Los Angeles wholesaler. A good scavenger and reef safe, but too large and hungry for small systems.

Colochirus robustus Ostergren 1898, the Yellow Sea Cucumber. To four inches in length.

Pentacta anceps, the Red Sea Cucumber. To a maximum length of about three inches. Plankton feeder, requiring large refugium contributions and/or cultured materials (e.g. Artemia).

Am surprised and disappointed that the Sea Apple, Violet Sea Cucumber is still sold in our interest... Pseudocolchirus violaceus (Theel 1886), et al. species, can be deadly toxic if disturbed... Sensitive to poor, changing water quality. Largely a filter feeder. Avoid.

Sea Lilies, according to most pet-fish writers are near-impossible to keep in captivity. I assure you this is not the case. They are “sticky” to touch, and therefore problematic to move (best to gently prod, have “walk up” net handles and bag underwater). Crinoids require seasoned (month’s established) systems with other peaceful tankmates; and some care in feeding (small materials; either from a refugium or blended by you; fed using a timer to temporarily switch off your mechanical filtration). Look for a smallish specimen (3-4 inches in diameter) that’s been at your shop for a week or more. Pay attention to its size; as they will shrink in time if undernourished.

     Crinoids occur in all colors of the rainbow; often two-tone.

      There are some small species of Echinoids, of a few inches test diameter; but these rarely show up in the trade. The non-spiny (slate, pencil) urchins get too big… frequently starving even in huge systems; and like their pin-cushioned cousins can push landscape over… IF some small individuals show up on your live rock, so be it; but I would not buy them for stocking.
At right, too toxic Athenosoma varium; below: Too spiky Diadema antillarum; bottom right Pencil/Slate Urchin, Heterocentrotus mammillatus; just too large.