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/Series: Livestocking Small: Pico, Nano, Mini-Reef's....... Marine Systems under 40 Gallons

Echinoderms; Seastars, Brittlestars, Sea Lilies & Sea Cukes for Small Marine Systems  

By Bob Fenner

 
Small Marine Aquariums
Book 1:
Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
B
ook 2:
Fishes

New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums
Book 3:
Systems

New Print and eBook on Amazon:
by Robert (Bob) Fenner

Surprising to many people is just how many numbers of spiny-skinned animals make up rocky reef fauna. In fact, they are the determinant group of life to be found there. Cursory careful observation, especially diving by night will reveal just how important this group is. Indeed, it has been written that they ARE the animals in shallow to deeper seas that to large extent decide what else lives there.

            Though most species of stars, sea cucumbers and crinoids get too large for the smallish systems in our purview here, there are quite a few suitable members that are on/off available to hobbyists.  

Seastars of (Small) Size/Use:

 


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).

 

My Favorite Genus, Fromia:
            What are we all looking for in livestock? For organisms that look attractive, are interesting behaviorally, which are hardy and adaptable… and readily available and not too dear/expensive. Amongst the Asteroids, this translates best as members of the genus Fromia. They’re gorgeously coloured and marked; out and about vs. shy and retiring most of the time, survive shipping and handling well, and generally don’t cost the proverbial (Seastar) arm or leg.

            Some best examples below: Fromia elegans, F. ghardaqana, F. indica, F. milleporella, F. monilis, and F. nodosa.

 

Stars That Aren’t (To Avoid):

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.

 

Brittlestars; Fabulous Little Ones:

            To heck with opportunistic omnivores like Hermit Crabs, and mysterious and lazy non-cleaner-upper snails; my vote for best clean-up crew members goes to small Brittlestars. Sometimes you can buy these outright from your stockist/LFS; other times, if you can secure very healthy live rock they may just “pop up” as hitchhikers. The systematics of small species, identification of small specimens is difficult, but here I’ll provide you with some image examples.

 

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.

 

Brittle/Serpent Stars to Avoid! Too predaceous and/or too big

 

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.

 

Gadzooks, Tiny Cukes!:

            Most Holothuroids get way too big for forty gallon or less volumes; and many of them have a nasty reflex defensive mechanism (see below). These Cuvierian Tubules are not just ungodly sticky, but venomous… if released, resulting in the loss of all livestock. Stick with the non-venomous, small species.
Some of the best choices and the very worst below:

 

 

 

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).

 

 

Beware This Destroyer of Worlds:

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.

 

Crinoids; Mysteries No More:

             

 

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.

 

No Urchins For You!

      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.

 

 

Echinoderm Selection Criteria:

1)      Look carefully for blemishes, bulges, evacuolations in the bodies of prospective purchases, and those of other echinoderms in their system. Animals with such “blems”, missing arms, tube feet… rarely survive.

2)      Select the more active individual/s… ignore those “just sitting there”. Motility is a good indication of vitality.

3)      Ask the animals to be fed in front of you. Even just some “food juice” added to an echinoderms system elicits action; demonstrable activity.

4)      Don’t buy “just arrived” specimens; never at “midnight madness”, “still in the bag” special sales. Most echinoderms die within a day of arrival at each step in the chain of custody… Let them rest before moving again.

 

Cloze:

            The Echinodermata is placed right next to the Chordata, the phylum that includes the fishes, and us. These are advanced organisms; some smaller ones suitable for aquariums of a few tens of gallons. They have similar needs for high, consistent water quality, a dearth of metabolites and no measurable metal in their water. In moving them, do keep them submerged (trapped air in their bodies can be trouble). Will you be fortunate to “inherit” spiny-skinned animals with your live rock? Maybe even purchase them directly?

Small Marine Aquariums
Book 1:
Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
B
ook 2:
Fishes

New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums
Book 3:
Systems

New Print and eBook on Amazon:
by Robert (Bob) Fenner

 

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