While most cnidarians require very bright illumination, there are several types that prefer shade or darkness. ORDER CERIANTIPATHARIA (Tube Anemones and Black Corals). Tube-dwelling anemones (Family Cerianthidae) have no symbiotic algae and thus do very well in the deep-reef aquarium microhabitat. Cerianthids may be distinguished from true anemones in that the former have two sets of tentacles. The outer rows are quite long, and the inner ones, sur-


Tube anemone (Order Ceriantipatharia)

Fromia Monilis

the tube and place it in the tank. It will soon construct a new tube and bury itself in the substrate. Tube anemones can catch small fishes and can sting other invertebrates. Make sure no other specimens are within reach of the anemones tentacles when fully expanded, and avoid fishes such as clown-fishes, hawkfishes, and seaweed gobies, which may attempt to perch in the anemone's tentacles with fatal results. Feed tube anemones a small piece of frozen marine fish meat once a week. Cerianthids are nocturnal and may not expand their tentacles if kept under bright illumination.

Black corals, or antipathari-ans, look nothing like tube anemones, but are classified along with them because of similarities in the details of structure and embryology. They superficially resemble gorgonians, as they are colonial and sometimes treelike, rounding the mouth, are much Black coral (Order Ceriantipatharia): often found and are stiffened by an axial skele-

shorter. Purple or brown tube on dimly lit deep fore-reef walls.

anemones (Ceriantheopsis ameri-

ton. Black corals often grow in a form that resembles a left-handed canus, Arachnanthus nocturnus) are often available and live corkscrew — the "anti" in their name is a reference to the buried in substrate, lining the burrow with a tube made of observation that most other natural spirals are right-

a mucus secretion. When freshly collected, the tube is usu- handed. Black corals were once collected for jewelry making ally heavily encrusted with mud. This should have been re- in Hawaii and the Indo-Pacific, because the dense, hard

Chapter Nine 225

axial skeleton of certain species can be polished and made ORDER ALCYONARIA (Soft Corals). While Tubastraea into jewelry. Small ones in the aquarium trade have been is the only commonly available stony coral that can do with-

One Soft Coral

called "spring corals" and are seen only occasionally. ORDER SCLERACTINIA (Stony Corals). Only one stony coral commonly available to the aquarist is suitable for the deep-reef tank, but it is a beauty. This is Tubastraea, the Orange Polyp Coral. Bright orange colonies the size of a tennis ball are often collected from caves and underneath ledges. Tubastraea is easy to care for. Orange Polyp Coral (Tubastraea sp.) Provide a good, strong current, directed sideways across the coral colony, not pointed straight at it. When the tentacles are extended, which can be stimulated by the addition of a small amount of food juices, feed each member of the colony on frozen plankton, brine shrimp, or a small piece of shrimp or fish. Feeding Tubastraea micrantha should be done in the evenings, two

Tubastraea Micrantha

out light, many soft corals are suitable for the dimly lit reef tank. Certainly the loveliest is the soft coral Dendronephthya, usually known as Tree or Flower Coral. Two species, D. klunzingeri and D. rubeola, are imported. Each appears to have been made from hand-blown glass. The loosely branched, fragile-looking colonies come in shades of pink and yellow-orange. Some species do poorly if exposed to bright light and may be challenging to keep. I suspect most failures are due to too infrequent feedings. Charles Delbeek has noted that this genus requires cool temperatures, a laminar current flow, and regular feedings of phytoplankton (cultured algae, "green water"). A related genus, Scleronephthya, needs shade and apparently feeds on detri-

or three times a week. Aquarists who take care to treat Tubas- tus. This whole group of nonphotosynthetic animals has traea in this way will be rewarded with the growth of new proved impossible to keep for many aquarists. Research on polyps over several months' time. This coral has reached 6 Red Sea species o{Dendronephthya and Scleronephthya in-

inches in diameter in careful hobbyists'tanks, and larvae have dicates that they feed most heavily on phytoplankton.

successfully established themselves to form new colonies.

Clearly they are being starved to death in too-new or too-

Arachnanthus NocturnusNon Photosynthetic Reef AquariumGorgonian Coral Tree
Tree Coral (Dendronephthya sp.)

Tree Coral CDendronephthya sp.)

226 Natural Reei Aquariums


Deep-water gorgonian (unidentified)

Red gorgonian with white polyps, perhaps Ellisella sp clean reef aquariums.) A breakthrough in satisfying their feeding needs will be required before they can be recommended to anyone other than experienced reef aquarists. ORDER GORGONACEA (Gorgonians). Most of the gorgonian species of interest are in Family Ellisellidae, the deep-reef gorgonians, such as the typical genus Ellisella. These gorgonians are usually red with white polyps and are nonphotosynthetic. They are confined to deep (60 feet or more) water, and are sometimes available for the aquarium.

Wilkens and Birkholz (1986) discussed these gorgonians briefly and reported that their experiences with them in the aquarium ranged from frustrating to easy. All nonphotosynthetic types required top-notch water quality, good currents, and twice-daily feedings to thrive and grow, along with an absence of filamentous algae. There was one notable exception, a Eugorgia species that was described as "the hardiest of all imported species for the aquarium." Judging from the picture of this specimen, it is the one commonly known as Red Tree Gorgonian, often imported from the Indo-Pacific. I, too, have found this to be an easy species.

Nonphotosynthetic gorgonians are frequently brightly colored — orange, red, pink, or yellow — often with polyps of a contrasting color. They do not require light and in fact will not thrive if the light is too bright. They also require cool water, no warmer than about 75 degrees F. Feeding twice daily on a plankton substitute, such as live brine shrimp nauplii and phytoplankton, is essential. (In the •ocean, there are usually two plankton "swarms" each day, controlled by the daylight cycle and the ebb and flow of the tides.) Like the soft coral Dendronephthya, nonphotosynthetic gorgonians extract a great deal of effort from the aquarist in exchange for the enjoyment of their beautiful colors. Most gorgonians, therefore, are suitable only for the advanced aquarist willing to dedicate the necessary time to their proper care and habitat.

Red Finger Gorgonian (Mopsella), which is sparsely branched like a dead tree, red with white polyps, is a hardy species that might be suitable for a first effort at keeping these organisms.

Inspect all gorgonians carefully for damage before purchasing. If the colored tissue is missing entirely in some places, but the polyps are expanded and the other areas of the specimen appear in good shape, the gorgonian is probably in good health. If the colored tissue is missing at the

Chapter Nine 227

Deep Water Coral

Acalycigorgia sp., a deep-water soft coral off Sulawesi

Yellow-polyped gorgonian (unidentified)

tips of the branches, prune off the internal skeleton just above the point where the colored tissue stops, using a pair of sterilized scissors. Underwater epoxies, such as Devcon, AquaStik, or SeaRepair can be used to attach gorgonians to rocks for stability or decorative effect.

A rather impressive aquarium could be created using deep-water or cave-dwelling cnidarians alone; however, there are other creatures that are suitable also.


Many species of sponges that are collected for the aquarium do best in shady locations, as they are easily "swamped" if algae growth (which is stimulated by light) gets started on them. Sponges have a porous body, and it is through the pores that they feed and acquire oxygen. If algae or detritus are allowed to accumulate, clogging the pores, the sponge will suffocate and die. Various species of sponges are imported from both the Indo-Pacific and Caribbean regions, but try to locate the beautiful bluzAdo-

cia. This sponge is sometimes imported from Indonesia.

There are three basic requirements in the care of sponges. Make certain that the sponge is never removed from the water. If it is, air may be trapped inside, and the sponge will slowly die from within. Second, never allow detritus or algae to accumulate on the surface of the sponge, as noted above. Third, supply good current. Sponges feed on very small particles and may absorb dissolved organic materials, such as proteins, from the water. No special feeding is necessary if the aquarium already supports sessile invertebrates. The physiology of sponges is poorly understood, but it is known that some species extract certain trace elements from the water. Regular partial water changes should provide sufficient trace elements.

Sponges will do well in the aquarium and may reproduce if these simple requirements are met. Several kinds may grow voluntarily on the decor and glass after the aquarium has been in operation for a while. The ability of some sponges to reproduce vegetatively is legendary: a standard college biology lab demonstration involves chopping up a living sponge in a blender, placing the puree in an appropriate environment, and observing how the sponge reag-

gregates and regenerates over the next few weeks. According to Stanley Brown of the Breeder's Registry, this technique

228 Natural Reef Aquariums individually or can be found on live rock specimens. All are very easily kept and need no special feeding. Sabellastarte may toss off its crown of tentacles in response to poor water quality. If these conditions are promptly corrected, however, the worm will regrow its "feathers" in a few months' time. Interestingly, it is thought that some sabel-lids also cast off their tentacles in preparation for reproduction. This event may manifest itself as a milky cloud flowing from the opening of the worm's tube. Such a cloud of eggs or sperm will provide food for other filter-feeding invertebrates in the tank and could result in development of additional worm specimens. In my aquariums, Sabella melanostigma, or a similar species, reproduces itself readily. I have not deter-can be employed successfully in the aquarium. Only certain mined if this occurs via sexual or vegetative means, but I species of sponges respond favorably to the procedure, how- have seen this worm growing in lovely colonies in many ever, and identification of sponges can be extremely difficult. hobbyists' tanks. Trial and error with available species is one approach to bringing sponges into cultivation for the aquarium hobbyist market.

Indo Pacific Ocean

Wild palette: sponges and other deep-reef invertebrate life of the Indo-Pacific.


All of the commonly available tubeworms will thrive without any special lighting and can thus be included in the deep-water tank. Available species include Sabellastarte sanctijosephi, which comes from Hawaii, and Spiro-branchus giganteus, which is found on reefs throughout the world. (See the discussion of the latter species, however, that appears on pages 182-191.) Various other tubeworms, including Sabella melanostigma, S. elegans, Spirographis, Spiro-branchus tetraceros, and many more, are either imported Fanworms often form colorful, gregarious clusters

Colorful Sea Urchin

Chapter Nine 229

Echinoderms starfish that will feed on other specimens in your tank. Sea urchins (Class Echinoidea) are vegetarians and are

Nearly all echinoderms prefer at least a shady spot in sometimes placed in the aquarium for algae control. How-which to retreat from time to time. This is especially true ever, urchins are really out of place in the deep-reef habitat.

wnicn to retreat rrom time to time, i nis is especially tru of brittle, serpent, basket, and feather stars, which are ac tive mainly at night. Deep-water species of serpent stars food source occurs, are often bright red in color. Brittle stars and serpent stars (Class Ophiuroidea) are not fussy eaters, although serpent stars, in particular, should occasionally be fed a small piece of fish or shrimp. Most of the time, these organisms will feed on stray bits of this and that, which they locate during their nocturnal excursions around the tank.

Feather stars (Class Crinoi-dea), on the other hand, and the Feather Star (Class Crinoidea): not recommended similar but distantly related basket stars (Class Ophiuroidea), are much more fragile. These specimens are not recommended for the aquarium.

With some exceptions, "regular" starfish (Class Asteroidea) are to be avoided in a tank filled with sessile invertebrates, as they have the habit of eating anything and everything. The exceptions, Blue Starfish (Linckia laevigata): a viable choice.

however, are quite desirable, and

They generally are found in shallower waters where their

Where Cnidarians Are FoundKelas Crinoidea

Among the sea cucumbers (Class Holothuroidea), an especially attractive genus is that of the sea apples, Pseudocolochirus, of which there are two or three species or color types imported for the aquarium. Sea cucumbers are either burrowers or filter feeders. The latter are best suited to the deep-water aquarium and can be recognized by the fact that their tentacles are feathery and densely branched, not shaped like little goblets or otherwise. Sea apples are conspicuously colored, advertising to potential predators that their flesh is toxic. Their eggs have been called "poisonous candy" for fish by Sprung and Delbeek (1994). Aquarists should be aware of potential problems that these organisms can pose for fish housed in the same aquarium. Otherwise, they are interesting animals and can make attractive additions. These include the Blue Starfish be long-lived in captivity if adequately fed. Other species of

{Linckia laevigata) and two species of Fromia — the Little filter-feeding cucumbers appear in shipments from time to

Red Starfish (F elegans) and the Orange Marble Starfish time. Some are quite colorful. Occasionally seen is a small,

(F monilis). Check an appropriate photographic reference to bright yellow species, often called "Little Yellow Cucumber,"

identify these species; a mistaken ID can result in having a that reproduces itself in the aquarium. Filter-feeding cu-

Serranocirrhitus Latus

Chapter Nine 231

Sunburst Anthias (Serranocirrhitus latus): superb aquarium N § fl G §

species, uncommon but well worth the extra effort to find.

Some of the most popular aquarium fishes are found cumbers may slowly starve if tank-generated plankton or in deeper waters. The Flame Angel, Centropyge loriculus, is added plankton substitutes are insufficient. The telltale sign an excellent choice for the deep-reef aquarium. It is usually of inadequate feeding is a reduction in the size of the animal. collected off Christmas Island in the Indo-Pacific. The

Since food requirements are a function of size, the Little Yel- Longnose Hawkfish, Oxycirrhites typus, an Indo-pan-Pacific low Cucumber does well, probably because of its compara- species found at depths ranging from 30 to 300 feet, is con-

tively minuscule demand for food.

fined to depths of about 90 feet in Micronesia. It is another

Burrowing cucumbers feed like earthworms, ingesting good choice. Many species of cardinalfishes, Family Apogo-the substrate and digesting the edible matter therein. Most nidae, live in caves during the daytime, emerging at night are found where rich sediments abound, as in grass beds. to feed. Various species of cardinalfishes are seen in aquar-They are thus better choices for the shallow-water aquarium ium shipments. Serranocirrhitus latus, the Sunburst Anthias, than for a deep-reef habitat. is a superb choice for a deep-reef or cave tank. It is usually found in small groups near caves, to depths over 200 feet, and is available to hobbyists sporadically.

A deep-reef slope, wall or cave habitat can be a startling Anyone seriously interested in mollusks in the and beautiful departure from the typical shallow-water ma-aquarium should purchase a good seashell identification rine tank. It demands much less in the way of sophisticated book and learn to recognize the various species. Accurate lighting, but can require real dedication to specialized feed-identification is of utmost importance with mollusks, since ing schedules and water changes. Advanced aquarists who their habits and diets vary widely. I have seen harmless are ready for the challenge of delving deeper into the un-species displayed side by side with predatory types in dealers' known may want to consider this biotope. In terms of color tanks. With perhaps 100,000 species of mollusks in the sea, and form, denizens of deeper waters are among the most one could spend a lifetime simply observing them under bizarre and fascinating in the reef environment, aquarium conditions. Herbivorous grazers, from the trochid and turbinid families, are frequently imported for algae con trol in the aquarium. These are easily, and now almost universally, included in all types of invertebrate aquarium displays. At the other extreme are species — such as most of the nudibranchs — so rigidly specialized in their feeding habits that they are impossible to maintain in a home aquarium. In between are a host of other mollusk species, including some that would make beautiful, intriguing aquarium subjects for the hobbyist willing to do the background work Longnose Hawkfish (Oxycirrhites typus): commonly available

Images And Names Cnidarians

and provide what the species needs to survive.

and an appropriate choice for the deep-habitat aquarium.

The COMPLETE guide to Aquariums

The COMPLETE guide to Aquariums

The word aquarium originates from the ancient Latin language, aqua meaning water and the suffix rium meaning place or building. Aquariums are beautiful and look good anywhere! Home aquariums are becoming more and more popular, it is a hobby that many people are flocking too and fish shops are on the rise. Fish are generally easy to keep although do they need quite a bit of attention. Puppies and kittens were the typical pet but now fish are becoming more and more frequent in house holds. In recent years fish shops have noticed a great increase in the rise of people wanting to purchase aquariums and fish, the boom has been great for local shops as the fish industry hasnt been such a great industry before now.

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  • oliver
    How to care Dendronephthya sp?
    7 years ago
  • aleksander
    What does soft coral look like?
    4 years ago
  • aman
    How do cnidarians keep internal conditions stable?
    4 years ago

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