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As a follow up to the previous Section on anemones in general, our focus here is the Order Ceriantharia, the tube anemones. As you will see, aspects of their selection, habitat and maintenance warrant a more full and separate discussion.
Tube anemones as a group share many/most of the same characteristics and general husbandry as the so-called "true" anemones, Order Actinaria. Here we'll re-emphasize these points as well as specialize in the tube anemones' particular needs and possible problems in captive care.
Classification & Distribution:
Kingdom Metazoa: Multi-celled animals.
Phylum Cnidaria: Stinging-celled animals; tissue-grade life, no organs, three cell layers.
Class Anthozoa: Single or colonial polyps; no medusa stage; no cover on stinging cells.
Order Actinaria: True anemones; with pedal discs; two ciliated mouth openings (siphonoglyphs).
Order Ceriantharia: Tube anemones; no pedal discs; one ciliated mouth opening.
These animals secrete a heavy, mucus tube that is added to by specialized stinging cells.
The same "tips" used for sizing up "true" anemones for purchase apply to tube types. Look for tears, discolored areas, flaccid, unfilled or otherwise non-displayed tentacles; and avoid those specimens. Additionally, healthy tube anemones exhibit a "cough" reaction when being removed from their tube or tank. If the individual in question does not forcibly eject water from it's terminal vacuole ("mouth/anus") on handling, leave it. See other notes below under acclimation.
Unlike "true" anemones, tubes are rarely artificially dye colored. Those gorgeous yellows, oranges, purples and blue/blacks are natural.
In the wild, the Ceriantharia may make dwelling tubes up to a few meters long in the soft substrate. Coating these tubes semi-continuously with layers of mucus facilitates their rapid retreat if disturbed.
In captivity, they have proven undemanding. Larger systems are preferable for three good reasons. Their burrowing behavior and expansive size, sometimes copious waste production, and stinging of tankmates dictate a minimum of forty gallons for just one specimen.
Depending on your set-up, more versus less substrate is preferable, the finer (4 mm or less diameter) the better; at least two inches or enough to cover all but the tentacular crown. Tube anemones have broadly long and tapering cylindrical bodies, a few to several inches long.
Some industrious aquarists' utilize a "baking-dish" contraption in one part of their tanks' to accommodate a tube anemone. Other ones I've seen make a hollow in an elevated rock area, chemically inert bottomless cones, tubes and pots to speed-up/provide spaces for new-comers just where they want them. Peter Wilkens describes the building of glass and foam living spaces in his aquarium display. Once their tube is formed the whole mass may be move to a suitable location in the same system.
Temperature ranges can be very wide indeed with tube anemones. As a diver I've recorded them in shallow, coastal areas that a re subject to wide and rapid environmental change. If your setting the thermostat for tube anemones alone, you can put them at a low point (let's say @ 70 F) to preclude too disastrous a drop; but otherwise, thermal fluctuation is not a problem.
Should be subdued, or alternatively the animal(s) should be placed where there is little light. Remember where these animals hail from. You'll want at least some full-spectrum fluorescent lighting to appreciate your tube anemones color.
At minimum, a simple biological filtration system is all that is required, but I do suggest the use of an outside power filter, either an outside power or canister type. A protein skimmer will more than make up for it's nominal costs in acquisition and operation, in keeping the water clean and clear.
Some additional circulation is warranted, but not necessarily super-vigorous. Once again, I shy away from the use of much airstone/air-powered water movement in a system with lots of filter feeders. The use of a separate fluid-moving pump or a power head are my choices.
When procured, all mucus and tube conglomeration should be cleaned away and discarded. I strongly advocate rinsing the new arrival(s) with established system water on arrival and carefully tossing the shipping water to reduce the chance of putting in loose stinging cells. I've found that extensive "mixing" techniques and quarantine procedures to be unnecessary with ceriantharians.
Anaerobic decomposition problems should be closely monitored with these animals due to wastes and tube-slime. One simple solution is to siphon out and rinse a portion of the substrate as a part of routine water change procedure. If only doing a portion every month or so, don't be concerned with interrupting bio-geo-chemical nutrient cycling.
Probably their most astounding performance is initial burrowing. This is accomplished by rapidly expelling water from their oral area (vacuole) through contraction, driving the pointed end of the animal into the bottom.
Can be a big problem. Tropical and temperate tube anemones do not mix well and can and will sting each other to death if too over-crowded. Some tropical species as individuals will mix. This becomes a matter of experimentation either at the dealer's or your system. I suggest a good eight inch spacing between a tube anemone and any other sessile organism, though some writers have reported success with virtual stacking of the same tropical species; which may be of different colors.
I have encountered some successful combination "true" and tube anemone tanks; but far more with lost animals. If you mix these different Orders provide very wide berth around the tubes.
The same 'standard exceptions' for tankmates of other anemones apply; triggers, puffers, large angels, large crabs, lobsters and big snails are verboten. Most worms, small shrimps and small hermit crabs are fine.
Ceriantharians do not go well in small aquaria with many species of numbers of fishes. Their habit of shedding stinging cells appears to be problematical. Dwarf Angels (genus Centropyge) and many other coral reef fishes cannot be kept with them for long. Slow moving species like the tube-mouthed fishes (Seahorses, Pipefishes), Mandarins (Synchiropus), et al. soon become costly food items. Damselfishes and monodactylids (Moonfish, Fingerfish) are cited as good company. Keep in mind that tube anemones are nighttime feeders for the most part.
Other Buddy Tank-mates:
Perhaps only the fat inn-keeper worm (Urechis) comes close to rivaling tube anemones for their depth and breadth of commensal (a form of symbiosis) relations. Within their tubes can be found many numbers of individuals of crab, bristleworm, horseshoe worm (Phylum Phoronida), other crustacean and worm species, The green algae in the genera Caulerpa and Udotea are frequently found in association with them as well.
Tube anemones are not symbiotic with Clownfishes! They will gladly eat them and other hapless subjects if presented the opportunity.
Has been observed in aquaria (Wilkens 1990). Two individuals left their tubes; swollen and with tentacles intertwined, floating at the surface. Some weeks late a large quantity of small pinkish-orange eggs were observed floating at the surface. None of the larvae lasted through a developmental (Planula) stage; presumably from lack of food.
They can move, and may, by pulling out of their tubes and basically allowing current to scoot them about. This can be a dangerous time to themselves and other company. By exhaling strongly through their oral cavity, a tube anemone may easily tear it's body or sting something else.
Foods/Feeding/Nutrition: Types, Frequency, Amount, Wastes:
Tube anemones are filter feeders; offering them large, meaty foods is contra-indicated; don't do it. Twice weekly feedings of live, frozen or macerated prepared foods circulated about and onto their tentacles while particulate and skimmer filtration is arrested is sufficient. More frequent, smaller feedings are better than the reverse.
The intensity of color seems to largely a function of nutrition. Vitamin supplement soaking of food, mashes of high quality prepared foods will ensure color enhancement and retention.
A great unknown. Tube anemones fall into the category of either altogether alive and almost impossible to kill, or outright dead. Other authors have listed victories with trimming away damaged or diseased tube body areas. I have never experienced success with such a procedure.
When collected and handled uninjured up to the time of your procurement, and offered a minima of food, water and space requirements tube anemones can make a marvelous display.
Ates, Ron. 1992. Tube anemones. FAMA 5/92.
Friese, U. Erich. 1972. Sea Anemones. T.F.H. Publications, N.J.
Lamberton, Ken. 1994. "Sloppy guts": the natural history of a tube anemone. TFH 12/94.
Mayland, Hans J. 1973. Cerianthus Marine Aquarist 4(5):73.
Ruffus, Heinrich. 1979. Tube Anemones. Aquarium Digest International #23, pp 40, 41
Wilkens, Peter. 1990. Wondrous flowers of the sea; tube anemones. TFH 3/90.