One of my favorite spots in the Keys is a huge, bowl-shaped tidepool just off U.S. 1. Protected from wave action by a sea wall of coral rock rubble, this pool is a giant natural aquarium. Dozens of species of macroalgae occur here. By far the most common are members of the large genus Caulerpa. C. proliféra has a simple flat blade (botanically, the "assimi-lator") that often spirals like a loose corkscrew as it grows upward. C. mexicana has a blade more reminiscent of a fern frond, that is, it is deeply notched. Less common species include C. racemosa, in which the blade looks like a bunch of grapes; C. peltata, which has an upright central stem with little lollipop-shaped "leaflets" attached along its length; C. sertularioides, with a blade that looks like a bird's feather; and C. verticillata, with short blades composed of a central thread bearing tufts of side filaments arranged in whorls along its length. These species of Caulerpa are adapted to scrambling over rubble, dead coral heads, and similar hard, irregular substrates. In the aquarium, arrange specimens attractively on top of a rock positioned in good light, and they will soon attach themselves and begin to grow.
Other species of Caulerpa are adapted to life in sandy or muddy habitats. These include C. paspaloides, which produces a tall, stiff blade crowned with feathery branches that give the overall appearance of a palm tree; C. cupressoides, with tough, squarish blades that are toothed along the edges; and C. lanuginosa, the blade of which is a fat, rounded rod covered with little projections that give it the appearance of a spruce tree branch. These three species require a fine substrate.
Under optimum conditions, growth of Caulerpa can be as much as an inch a day, so pruning will be necessary. The prunings can be fed to herbivorous fish or can be used to start new plants. A single blade of any Caulerpa can be partially buried in sand and will form a complete new plant within a few weeks. Natural growths of Caulerpa are probably "pruned" regularly by algae-eating animals. Pruning seems to be important in preventing Caulerpa from undergoing sporulation, a process in which the internal contents of the blade become reorganized, forming free-swimming reproductive cells. The first time I observed this phenomenon, I was amazed at the speed with which the changes in the seaweed occurred. At first, the blade takes on a veined appearance, as green chloroplasts cluster around cell nuclei and new walls of cellulose partition off the blade into myriad tiny packages. Within a few hours, these spores will be released into the water, each endowed with a flagellum that permits it to swim, leaving behind the dead, translucent husk of the parent.
On the shady side of large boulders in the inshore zone may be found colorful sponges, including Chondrilla, the Chicken Liver Sponge, which can be kept successfully in the aquarium. Scattered among rubble and pebbles, the lovely
Giant Fanworm CSabellastarte magnifica): fascinating to behold and one of the best invertebrate choices for beginners.
158 Natural Reef Aquariums giant fanworm, Sab ellas tar te magnifica extends its feathery fan, feeding on plankton. These worms, preferring quiet, sheltered locations, are common in boat slips and on submerged pilings. Other species of fanworms, though none as large as Sabellastarte, are abundant in such areas as well.
Shallow-Water "Flower Carden"
Among the anemones, Condylactis, Bartholomea and Phymanthus are hardy, colorful, sometimes have interesting symbionts associated with them, and are gloriously abundant in shallow waters surrounding the Florida Keys. I have
So-called Flower Anemones from Florida waters occur in a variety witnessed vegetative Curleycue Anemone CBartholomea annulata) with its claw-
reproduction in Bar- snapping partner, the Curleycue Shrimp (Alpheus armatus).
tholomea and sexual reproduction in the other substrate. As a student and in my salad days as a biology two species (actually, instructor, I observed these lovely invertebrates on numer-the release of sexually ous expeditions to Pigeon Key, directly underneath the old produced offspring Seven Mile Bridge. At the edge of the island, not quite un-from a brooding "fe- derneath the bridge, and thus in full sun for about ten hours male" in each case) in a day, lay a patch of gravelly sand dotted with Phymanthus the aquarium, suggest- crucifer. Since collecting around the island was forbidden, ing possibilities for this patch had been undisturbed for a long time and covered captive propagation. many square yards. At low tide, the area was left high and Rock or Flower- dry, the gravel moist and cooling as seawater evaporated un-Anemones (Phyman- der the terrific sun. The anemones would be withdrawn into thus crucifer) live in the gravel, waiting for the sea to return. When it did so, they crevices between the would slowly emerge, revealing their intricate colors and cobbles, often in only a patterns as they stretched to expose themselves to the sun. few inches of water. The anemones were of every hue possible for this species, When the rocks are ex- and I spent hours wading in that "flower garden," admiring posed at low tide, or the seemingly infinite variations.
when the anemone is Phymanthus crucifer is a highly variable species, with var-
disturbed by inquisitive iegated tentacles located just at the margin of the oral disc of lovely hues and color patterns fingers, it retracts com- and a very short, stubby column, often sporting protective and include a number of species pletely beneath the pink, purple, and green pigmentation. Other species called
Chapter Six 159
"Flower Anemones" may be superficially similar in appear- together in the aquarium, as males will fight until one is dis-
ance, but the tentacles are smooth, not knobby as they are membered.) When the anemone is approached by a fish or in Phymanthus. All are easy to keep, but coming as they do diver, the shrimp marches boldly from its burrow and emits from very shallow water, they need bright light. a loud "Pop!" using a claw specialized for this purpose. The
Another anemone that retracts into a crevice when dis- sound is audible from a considerable distance and is appar-
turbed is the Curleycue Anemone (Bartholomew annulata). It ently enough to frighten away fishes that would otherwise is unmistakable. Golden-brown to cream-colored, all spec- feed on the anemone. In this fashion, the anemone is pro-
imens have rings of white spiraling around the tentacles, tected by the shrimp. The shrimp, in turn, receives protec-
from which trait its common name is derived. This tion from shrimp-eating fishes, owing to the stinging anemone will not only sting other anemones, it can eat tentacles of the anemone.
them, so beware — although because of its symbiotic al-
Other shrimps, such as Pederson's Cleaning Shrimp gae, it does not need to rely on catching food. Several species (Periclimenespedersoni), Sexy Shrimp (Thor amboinensis\
of shrimps are often found in association with the Curley- and Spotted Cleaning Shrimp (Periclimenes yucatanicus) may cue Anemone, and an interesting aquarium could be set up seek shelter among the tentacles of the Curleycue featuring this community of species. In a burrow at the base Anemone. Their long, white antennae, together with dis-
of the anemone live pairs of Curleycue Shrimp (Alpheus tinctive swaying movements, advertise the services of armatus). Males can be distinguished by their striped an- cleaner shrimps to fishes seeking removal of parasites and tennae. Each pair of shrimp stakes out a particular anemone dead tissue. Fish approach the shrimp's "cleaning station"
as home turf and will vigorously defend this position against and indicate a desire to be cleaned by adopting special pos-
any intruder, even fish much larger than the shrimp. (For tures or color patterns. The shrimp will then leave the pro-
this reason, only one pair of Curleycue Shrimp can be kept tective tentacles of the anemone and alight on the fish's
Spotted Cleaning Shrimp (Periclimenes yucatanicus) on a Florida Pink-tipped Anemone (Condylactis gigantea).
Atlantic Carpet Anemones iStichodactyla helianthus): attractive, but not recommended as appropriate aquarium subjects
160 Natural Reef Aquariums body, moving about — even inside the mouth and gill cov- protection from predation that true cleaner shrimps enjoy, ers — extracting parasites, dead tissue, and loose scales. (Fish rarely eat cleaners, as the latter provide a valuable ser-These the shrimp eats, so both fish and shrimp derive ben- vice.) P. yucatanicus associates with Condylactis gigantea and efit from the cleaning relationship.
with the Antler Anemone, Lebrunia danae, as well as with
A hippolytid shrimp, Thor amboinensis is probably not Bartholomea, the Curleycue Anemone, a cleaner but is always found in association with anemones. In the Atlantic, it associates with the Curleycue Anemone and the Atlantic Carpet Anemone, Stichodactyla helianthus. (The latter anemone species is not a good aquarium subject.) These delightful little shrimp were once readily available, but now are rarely imported. It must, like all other anemone shrimp, be kept with an appropriate host. Thor occurs in the Indo-Pacific as well as the Atlantic and Caribbean. In the Indo-Pacific, this shrimp associates with corals such as Heliofungia, as well as with various anemones.
Most anemone shrimp species belong to the Family Palaemonidae and to a single genus, Periclimenes. One should obtain the shrimp and its host together. Mated pairs of shrimps are sometimes available, and the two will share a single anemone. Otherwise, attempting to keep two shrimp in a single anemone may result in a territorial squabble. Pederson's Cleaning Shrimp (Ppedersoni) occurs on several anemone species, perching in the tentacles and swaying back and forth to attract "customers." It rarely leaves the anemone, except to carry out its cleaning services. The body of this shrimp is transparent, with attractive white and purple stripes. Like most cleaners, it has white antennae. It grows to just over an inch in length. P yucatanicus is a bit larger, also transparent, and is marked with distinctive tan and white saddles on the back of its carapace. The legs are banded in white and purple, and there is a series of purple dots, surrounded with white circles, along the sides of the abdomen and on the upper surface of the tail. The antennae are white, but there is no direct evidence that P yucatanicus is actually a cleaner. It may be a false cleaner, Florida Pink-tipped Anemone (Condylactis gigantea): note mimicking the behavior in order to benefit from the same shrimp hiding deep in the mass of stinging tentacles.
Commonplace in the inshore zone is the tiny Tricolor Hermit Crab, Clibanarius tricolor. All hermit crabs protect themselves by making use of the discarded shell of a dead snail, and this species is usually found in the small shell of a common species, Bat-telaria. Hermit crabs are found on all shores, and most species from the Tropics are colorful. The Tricolor Hermit s name derives from the red, yellow, and blue markings on its legs. It is seldom larger than an inch. Being very hardy, hermit crabs are often the first invertebrate to be kept by the beginning aquarist. A few hermit crabs can be included in any marine aquarium and make excellent scavengers. Make sure that the species is not one that grows large, however, since large hermits can be destructive.
Throughout the inshore zone, among rubble, under rocks and in crevices, brittle stars abound. While not particularly popular with aquarists, owing to their secretive habits, brittle stars make a fine addition to the aquarium. Many species sport attractive colors and patterns, and all are excellent scavengers, coming out at night to feed on bacteria, plankton, debris, or bits of dead animal matter. One species, the Reticulate Brittle Star (Ophionereis reticulata), is especially abundant among beds of the calcareous alga Halimeda. This brittle star has a unique way of defending itself against predators when it leaves the safety of the Halimeda to forage at night. When disturbed, its entire body flashes with a brilliant yellow-green light (bioluminescence). This reaction presumably dazzles the would-be predator, allowing the brittle star sufficient time to escape. Brittle stars are so named because they are easily damaged by handling. They will not survive in the aquarium unless provided with shelter into which they can retire to escape the light.
Another useful resident of the inshore zone is Astraea tecta americana, the American Star Shell. (Another subspecies, A. tecta tecta, occurs in the West Indies.) This mollusk (Gas-tropoda-Turbinidae) is valued by aquarists for its propensity to consume algal turfs. It also occurs in grass beds and on the back reef. Several species of keyhole limpets (Diodora, Gas-tropoda-Fissurellidae) are also found in the Keys, from shallows to great depths. All of the shallow-water forms feed on algae, and so are often included in aquarium displays for functional, rather than aesthetic, reasons. Limpets are capable of reproduction in the aquarium, a trait which further recommends them to hobbyists.
Fish species appropriate for this biotope would include any of the common shallow-water damsels, such as the Beau Gregory (Stegastes leucostictus), various wrasses, such as the colorful Bluehead Wrasse (Thalassoma bifasciatum), as well as numerous blennies of the Keys and the Caribbean that appear in the trade, often unidentified. Juveniles of many other species also pass through these shallows, and a young Blue Tang (Acanthurus coeruleus), French Angel (Pomacan-thus paru), Porcupine Puffer (Diodon hystrix) or Goldspotted Snake Eel (Myrichthys ocellatus) would not be out of place here, although any of these would outgrow a small tank.
Major areas of the inshore zone of the Florida
Keys are occupied by beds of Turtle Grass (Thalassia) and Manatee Grass (Syringodium). These angiosperms (flower-
American Star Shell (Astraea tecta americana): an excellent algae grazer.
162 Natural Reef Aquariums ing plants) can be grown in the aquarium if provided with ings. After becoming acclimated to the aquarium for a few a 4-inch-thick substrate of fine silt and sand. Including nu- months, seahorses can sometimes be trained to accept non-
merous burrowing organisms that help to keep the substrate living foods and may even take food from the aquarist's fin-
stirred up makes it possible to duplicate the Turtle Grass gers.
habitat. The nutrient-rich substrate of the Turtle Grass beds Reticulated sea stars, the "Bahama Star" of the aquarium is home to hundreds of species. Here one finds the Florida trade (Ore aster reticulatus) and the Five-toothed Sea Cu-
Pink-tipped Anemone (Condylactis gigantea) in abundance. cumber (Actinopyga agassizit:), which carries its teeth in its
Formerly known to many as C. passiflora, this is probably anus rather than its mouth, are large, conspicuous inhabi-
the most common and widely available of all anemones. tants of the Turtle Grass bed. The Five-toothed Sea Cu-
Specimens vary in color, generally shades of pink, cream, white, or a combination of these. (C. gigantea is variously called the Florida Pink-tipped, Haitian Pink-tipped, or Giant Anemone in the aquarium business.) Forms vary considerably: the column may be white, pink, or reddish in color, and the tentacles are cream
cumber is sometimes host to the Pearlfish (Carapus bermudensis), which lives inside the cucumber s digestive tract, emerging only at night to feed on small invertebrates. Long-spined Sea Urchins (Diadema antillarum) and the Queen Conch (Strombus gigas) were once common in Turtle Grass, but a decline in their num-
to greenish in color with or with- Florida Pink-tipped Anemone (Condylactis gigan- bers has resulted in these two out a definite pattern of shading. tea): common, inexpensive, and relatively hardy.
This species grows both in reefs and Turtle Grass beds, where it tends to be smaller.
species being protected in Florida waters. Several small coral species waters, oeverai small coral species are found in the grass beds, and all, according to researchers, r»nn Ka rn p^oorrnl lir in f no nnnnrmm M/^r»^ rvi f Kapo nt-a
The amusing Variegated Urchin (Lytechinus variegatus), can be kept successfully in the aquarium. None of these are sometimes called the Carrier Urchin because of its habit currently available to hobbyists, however, since all corals in of carrying objects as camouflage, and the Lined Seahorse American waters are protected. This may change with the
(.Hippocampus erectus) are other grass bed dwellers. Sea- advent of live rock mariculture. Some live rock farmers in horses have long been popular as aquarium subjects, but the Florida have already received permits to sell stony coral beginner should be warned that they are challenging to colonies that develop on their "rock farms."
maintain. Aside from requiring living foods, seahorses are
If genuine Turtle Grass is unavailable, you may want to frequently inf ected with a variety of pathogens and para- consider substituting plastic replicas of the freshwater plant sites. Collectors may not handle seahorses properly, and the Vallisneria, commonly sold in aquarium shops. Interplant stress of capture and shipment may cause them to succumb this with live macroalgae, or include a few scattered pieces of to infections. All seahorses should be carefully medicated aquacultured live rock, preferably with small stony coral upon receipt. A supply of live guppies, adult brine shrimp, colonies present. To help control filamentous algae, include and grass shrimps should always be on hand for daily feed- a few of the cultivated juvenile Queen Conchs now being
Chapter Six 163
Five-toothed Sea Cucumber (Actinopyga agassizii)
Variegated or Carrier Urchin (Lytechinus variegatus)
Queen Conch (Strombus gigas)
offered. Sea cucumbers and brittle stars will help to keep the tus)> an ever-active, attractive wrasse. Two other wrasses sand stirred up.
usually associated almost exclusively with Turtle Grass beds
One fish associated with Turtle Grass is the Sergeant can usually be obtained by special order if your dealer has ac-Major Damselfish (Abudefduf saxatilis). Commonly avail- cess to a good collector in Florida or the Caribbean. These able and inexpensive, its hardiness is legendary. Other are the Blackear Wrasse (H.poeyi) and the Dwarf Wrasse piscine inhabitants for a Turtle Grass habitat tank might (Doratonotus megalepis).The latter lives only in seagrass and include the widespread Slippery Dick (Halichoeres bivitta- alters its coloration to match its habitat. Since the Dwarf
Wrasse reaches only 3 inches in length, it is a good choice for a smaller tank. Several wrasses can be kept together and make for a consistently lively display.
Many other larval and juvenile fishes are plentiful in the grass beds, where they find both food and shelter in abundance among the fronds. The choices are broad for this habitat, and a listing of fishes typical of the Keys area is included in Chapter Ten.
Antler Anemones CLebrunia danae): branching tentacles.
Open waters of the lagoon zone may be dotted with tiny patch reefs, and here an abundance of organisms more commonly seen on the reef proper may be found. Both the Curleycue Anemone and the Florida Pink-tipped Anemone may be seen here. The Antler Anemone (Lebru-
164 Natural Reef Aquariums nia danae) occurs here and there in the lagoon. Lebrunia can coax the fishes to settle down in a spot that makes it easy has two types of tentacles, one set is short and closely cir- to observe their behavior. Jawfish are gregarious; a colony cles the mouth, the other set is much larger and branches re- of half a dozen or more can be maintained if the tank is large
peatedly, not unlike the antlers of a deer. This is also known as the "Stinging Anemone" in south Florida. The latter name is descriptive — beware.
Sandy or muddy bottoms with rubble are often carpeted with the Green Sea Mat (Zoanthus sociatus). This colorful and hardy species is at home in any aquarium with sufficiently bright light. I have seen Green
Sea Mat colonies completely exposed Sea Mat or Mat Zoanthid at low tide, baking under the tropical CZoanthus pulchellus) sun at temperatures in excess of 100 degrees F. No wonder this species is hardy in the aquarium! It is less commonly available these days, due to collecting restrictions.
To create a lagoon tank featuring sea mats and other shallow-water invertebrates, an aquarist would be hard-pressed to find a more appropriate and appealing species than the Yellow-headed Jawfish (Opistognathus Yellow-headed or Pearly Jawfish aurifrons), sometimes called the Pearly (Opistognathus aurifrons) Jawfish. This burrowing species needs
enough and shelter is sufficient. Do not place jawfish in an aquarium with anemones, however, as the fish is prone to becoming a meal for the cnidarian. Instead, populate the aquarium with invertebrates from the grass beds (many of which are found in the lagoon) or with specimens of one or more of the soft corals discussed in the following section.
Not all of the lagoon bottom in the Keys is strewn with rubble and sand, which gives rise to the type of microhabitat frequented by Curley-cue Anemones, nor is it all soft, silty pastures of Turtle Grass. In many places, the Key Largo limestone strata are exposed and are largely bare of sediments. It is in this kind of hard-bottom lagoon that a sort of inshore reef occurs, dominated by the soft corals called gorgonians. I like to think about 6 inches of sandy substrate, including a few smooth of these areas as "gorgonian forests," for they share some pebbles with which it can reinforce the walls of its burrow. similarities with the great belt of coniferous forests that en-
The tunnel is often constructed beneath a sheltering rock, circles the Earth at the northernmost limits of the temper-
and careful placement of a flat piece oflive rock, supported ate zone.
an inch or two above the tank bottom by pieces of rock
One such forest occurs just beyond a seawall along the buried in sand and pebbles, will create a perfect site for a western side of U.S. 1. One can easily wade out a few yards rocky cave. Chances are good that the jawfish will be enticed and snorkel over the stand of gorgonians. They are very uni-to set up housekeeping here, and with some forethought you formly spaced, and all are approximately the same size. The
Gorgonacea includes sea whips and sea fans; colonies are branched and treelike, with the branches sometimes fused into a net (sea fans), or sheetlike, spreading over the substrate. In either case, they are stiffened by the protein gor-gonin, with or without calcified elements called spicules. In the upright species, there is an axial skeleton overlaid with cortical tissue (the colorful part of the creature) in which the polyps are embedded. The axial skeleton is absent in the encrusting types of gorgonians.
There are many families of gorgonians, and individual species maybe difficult to identify. Accurate identification is based upon the presence or absence of spicules and upon the shapes and colors of these elements when examined under a microscope.
To prepare a specimen for study, one must place a bit Sea Plumes or Sea Feathers (Pseudopterogorgia bipinnata): of the cortical tissue on a microscope slide and add a drop commonly available and readily propagated from cuttings. of laundry bleach. The bleach dissolves away the soft tissues, leaving the skeletal elements intact. Examination of this predominant color of these soft corals is deep purple, prob- preparation to identify the different types of spicules present
picpaiaiiuii lu luciiuiy inc uiiicicm iypcb ui t>piLuicb picbciu is required for positive identification, which even then may hp hevonrl the riinshihties of sll hi if those who snerialive in ably owing to the production of pigments that shield them from the eff ects of ultraviolet light. The water here is barely be beyond the capabilities of all but those who specialize in
4 feet deep, and the pale-colored limestone bottom reflects studying this group. There are some broad generalizations to the sun, meaning that these organisms are receiving just be made about the commonest types of gorgonians, how-
about the maximum amount of illumination possible. This ever. The following is a partial list of families and genera is the Gulf of Mexico side, and the low waves keep the gor- found in the Florida Keys and the Caribbean, which sup-
gonians swaying back and forth in constant motion. When ply most of the gorgonians collected for the aquarium trade, the tide turns, the directional flow of the water is quite per- FAMILY BRIAREIDAE — the encrusting gorgonians (ex-
ceptible. The stiff yet flexible skeleton of the gorgonians ample, Briareum asbestinum):
seems ideally suited to life in this locale. Each is firmly ce-
Most gorgonians are branching, upright forms, but mented to the solid rock, and movement is facilitated by there are also spreading types, typified by the pinkish Ery-
several inches of "trunk" protruding straight up from the thropodium caribaeorum. In this species, which is sometimes base before any branches occur. This design apparently called Brown Encrusting Soft Coral, the skeleton is sheet-
works as well for gorgonians as it does for trees, in terms of like and rubbery, without calcified spicules, and spreads over
▼ f jh a a>v/ wv v/ t v x^ adk xx ^^ '—' a ^^ v a a.jl a jl s^ v/ jl v v-' w c/ -ju v ju v a. w w w ^
coping with the forces of moving water or wind.
rocks and other solid surfaces, often colonizing the dead
Gorgonians are cnidarians consisting of colonies of in- skeletons of other gorgonians and so appearing to be a dividual polyps with tentacles in multiples of eight. Order branching species. This one has grown quite well in one of
166 Natural Reef Aquariums
rum) colony: will spread under good lighting.
my aquariums, starting from a single polyp attached to a piece of live rock.
As indicated by their golden-brown coloration, the very large tentacles of E. caribaeorum are filled with zooxanthellae, but they also show a feeding response, expanding when something nutritious, like brine shrimp juice, is Encrusting gorgonian iErythropodium caribaeo-in the water or if the sediments in the aquarium are stirred up. Wilkens and Birkholz (1986) reported a similar response in the nonphotosynthetic gorgonians. Kaplan (1982) suggested that gorgonians may be specialized for photosynthesis as the primary feeding mode, since the polyps are expanded mostly during the daytime, when plankton is less abundant. Determining the dominant source of nutrition for Erythropodium would make an interesting research project. In any case, it is a good aquarium species and rather commonplace in Florida, so it should not be difficult to obtain a specimen. Deadman's Fingers or Corky Sea Fingers
Another species that lacks a (Briareum asbestinum): readily regenerates, carbonate skeleton is Briareum asbestinum, also called Deadman's Fingers. The colony is genera. Collections from shallow water, as opposed to the composed of fat, pinkish brown branches with huge, feath- reef itself, will probably be dominated by species of Plexaura ery, brown polyps that appear fuzzy. Briareum sometimes and Muricea.
forms branches, but I have most often encountered the en- FAMILY GORGONIDAE — the sea fans and sea feathers crusting form in the field. It is probably the most common (examples, Gorgonia, Pseudopterogorgia):
species in areas where the substrate is unstable, for it can grow quickly and regenerates readily from broken pieces. It is a good choice for the aquarium and can be easily propagated. Briareum may be confused with the Brown Star Polyp (Cornularia) but this should not be a problem if the source of a specimen is known, as the Brown Star Polyp is found only in the Indo-Pacific. FAMILY PLEXAURIDAE — the bushy gorgonians (example, Plexaura):
The several genera in this family include most of the species that one will see in the aquarium trade. Plexaura, with at least three species, shows distinct growth forms depending upon the water depth at which it grows. In the genus Muricea, the branches of the colony are spiny or prickly due to the size of the skeletal elements. Eunicea, with many species, usually has protruding knobs or bumps from which the polyps extend. Plexaurella has tall, sparse, thick, and very fuzzy branches. All are widely distributed gorgonian
Sea fans (Gorgonia spp.) are specialized gorgonians in which the flat branches are very finely divided and fused together to form a net. Sea fans are rarely seen growing inshore from the reef in my experience. Sea fans can be successfully maintained in aquariums suited to stony corals. Sea fans should be oriented so that they are spread perpendicular to the current. In fact, orientation may be an important key to success with most gorgonians.
Sea fans are not regularly available in aquarium shops. On the other hand, sea feathers, Pseudopterogorgia and Pterogorgia, are frequently to be had. One common name often applied to these gorgonians is Purple Frilly Gorgonian. In these genera, the branches arise in one plane from opposite sides of a central stalk, creating the overall appearance of a feather. In Pterogorgia, the branches are flat, with polyps confined to the edges, while in Pseudopterogorgia, the branches are rounded and the polyps are uniformly distributed along them.
Gorgonians from shallow waters in Florida and the Caribbean are commonly photosynthetic and are colored purple, green, or brown, with mostly brownish or greenish polyps protruding from the skeleton. They fulfill the same ecological roles in the Caribbean that the leather corals fulfill in the Indo-Pacific. While sometimes regarded as difficult to maintain in the aquarium, photosynthetic gorgonians respond well to the same conditions provided for stony corals. They demand bright light and vigorous water movement. A well-established natural aquarium suits them, but it should have auxiliary pumps or powerheads controlled by a wavemaker to provide plenty of turbulence. Water movement is essential for all gorgonians, especially for those that are entirely photosynthetic and absorptive in their feeding behavior. These can be recognized by their tiny polyps in which tentacles are rudimentary or even absent. Clearly, these little guys cannot catch plankton and so depend upon currents to bring nutrients and carry off wastes, while photosynthesis by their zooxanthellae provides calories for growth and development. Upright types grow attached at the base to a rock and should be mounted in this fashion in the aquarium, using waterproof epoxy, unless collected already attached to a suitable base (highly desirable). A number of individuals are now offering propagated gorgonians for sale, usually smaller branches attached to pieces of live rock. Coming from captive stock, these are often hardy and easier to acclimate than wild-collected gorgonians.
Not all gorgonians are constructed according to the same body plan, although the branching ones do appear superficially identical. In some, the branches are round in cross section, with polyps arranged more or less uniformly over the whole surface of the branch. In others, the branches are triangular in cross section, with polyps usually confined to the apices of the triangle, and in still others, the branches are flattened blades, with polyps arrayed only on the edges. These differences probably represent adaptations to environmental conditions that vary in both the degree of exposure to sunlight and in the nature of currents prevailing in the gorgonians preferred habitat. We know that stony corals alter their growth patterns depending upon ambient light,
Bahamian Sea Fan (Gorgonia flabellum): can thrive in a reef tank with vigorous currents.
168 Natural Reef Aquariums
Shaving Brush (Penicillus dumetosus)
Rolled-blade Alga (.Padina boergesenii)
Mermaid s Fans ÍUdotea spinulosa)
Watercress Alga (Halimeda discoidea)
Calcareous Green Alga (Halimeda sp.)
Pinecone Alga CRhipocephalus sp.)
becoming flatter and more platelike with increasing water depth. In areas subjected to a great deal of turbulence, as opposed to directional flow, there would seem to be no special advantage to the orientation of the polyps, or indeed of the whole gorgonian, with respect to water movement. In other localities, however, directional flow may predominate, and the polyps might be arranged so that all are "facing into the wind" or, in this case, the current, which brings food and oxygen and carries away wastes and reproductive cells. Sea fans are almost always perpendicular to the prevailing currents, and they are of the flat-stemmed type of gorgonian. Careful inspection of a sea fan with expanded polyps will show that the polyps are only found on the edges of each tiny branchlet and that all seem to stretch toward the incoming water flow. Placement of gorgonians with attention to these specializations should enhance their likelihood of surviving and growing in the aquarium. Nonphotosynthetic gorgonians are, in my experience, nearly always of the round-branch type, with uniformly distributed polyps, the better to catch food arriving from any direction.
MACROALGAE. Down among the bases of the gorgonians, calcareous macroalgae fulfill roles similar to those of the shrubs and herbs of the forest floor. Udotea flabelliforme, U. cyathiformis, Penicillus c api tat us, P. dumetosus, Halimeda in-crassata, H. discoidea, Rhipocephalus phoenix, Avrainvillea nigricans, Cymopolia barb at a, Dasycladus vermicularis and Acetabularia crenulata all occur in the gorgonian forest in abundance. Caulerpa, interestingly, is not so common, probably because only a few species of this tropical seaweed can make do with smooth, solid rock for a substrate.
There are three major groups into which macroalgae may be sorted. These groupings are based upon pigmenta-
tion. Perhaps most familiar are the green algae, (Chloro- the order in which corallines are placed. All of the coralline phyta), with Caulerpa being a typical species. Red algae species are placed in one family, Corallinaceae, distinguished
(Rhodophyta) are typified by species such as Gracillaria. by the calcified body structure.
(The ured slime" algae that sometime reach plague propor- Coralline algae are either crustose (thinly encrusting)
tions in the aquarium are not in this group.) The third group, or articulated (upright and branching) and are found in all brown algae (Phaeophyta), includes the giant kelps and nu- seas, although they are most abundant in cold, agitated wa-
merous other species that live in cool waters, although there ters. They tolerate low light intensities and are found at are several tropical species, notably Sargassum.
greater depths than other kinds of algae. Genera and species
Among the most common algae at any depth are several of corallines are separated by studying the details of the species of mauve or purple coralline, or calcareous, red al- sexual reproductive cycles, usually by microscopic exami-
gae that encrust the undersides of rocks in shallow waters, nation of specimens grown under laboratory conditions, able to subsist on the sunlight reflected up to them from The average hobbyist will therefore be unable to identify the sea bottom. Given conditions to their liking, these al- with accuracy any corallines that he or she may encounter, gae will reproduce in the aquarium, encrusting the glass They can be subdivided into two groups: those that undergo and other objects. Coralline algae are regarded as being de- sexual reproduction only in the summer months and those sirable in any aquarium with live rock. Besides being at- that do so either year-round or at a season other than sum-
tractive, these species indicate by their presence that corals mer. Presumably, the tropical species that are usually found can grow in the tank as well.
on live rock in the aquarium trade are reproductive year-
There are two subclasses of Rhodophyta, and one, the round.
Florideophyceae, contains all of the red algae species that are
Among the green macroalgae (Chlorophyta) found on multicellular, capable of both sexual and asexual reproduc- rocks, Dasycladus vermicularis, which looks like 3-inch tion, and possessing multinucleate cells with disc-shaped lengths of green pipe cleaners clustered together, and chloroplasts. Pit connections, a distinctive microscopic fea- Batophora, a relative of Dasydadus that looks like clusters of ture of the cell wall, are prominent. There are nine orders, small, green bananas, are frequently present, distinguished on the basis of details of the development of For our purposes, the green macroalgae of shallow wa-
the reproductive organs, with Order Cryptonemiales being ters may be divided into two groups: those that produce a
Flat Twig Alga (Amphiroa tribulus)
Crustose coralline algae (Rhodophyta)
Lavender coralline algae (Rhodophyta)
170 Natural Reef Aquariums
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