Volume 8, Fall 1991

THE SHARKS OF THE FAMILY HEMISCYLLIDAE: THE BAMBOO AND EPAULETTE SHARKS

By Scott W. Michael

There are a number of sharks available on the marine fish market, but most are inherently unsuitable for the home aquarium. For example, nurse sharks and wobegongs attain sizes of more than 2 meters, exceeding what is suitable for most home tanks. The more active leopard and smoothhound sharks are not reef dwellers and prefer large, open swimming spaces that cannot be offered by the majority of "living room oceans." There are representatives of one shark family, however, that do show up in local fish stores and are ideally suited to the larger home aquarium. These are the hemiscyllids, known commonly as bamboo and epaulette sharks.

What characteristics make the members of this family perfect for the larger home aquarium? First, the largest members of the family attains a maximum length of only 107 centimeters. Second, these sharks occur in tropical areas and therefore do well in the warmer temperatures (22-27 degrees Celsius) maintained in most home aquaria. And third. the hemiscyllids behave differently from many other sharks.They spend most of their time in tide pools, in staghorn coral beds and under table corals. Because they are used to living in confined spaces, they adapt readily to the limited space available in most home aquaria. Anatomically, they are well suited to it. Slender bodies enable them to slip between coral branches and into tight reef fissures, and they can use their muscular pectoral and pelvic fins like legs to crawl over the sea floor.

The family Hemiscyllidae contains at least twelve species in two genera, four of which are available to the home aquarist from time to time. The genus Chiloscyllium is characterized by subterminal nostrils, a long snout, and no prominent ridges over the eyes (Compagno, 1984). Three species from this genus are available to U.S. aquarists. They are the brownbanded bamboo shark, Chiloscyllium punctatum, the whitespotted bamboo shark, C. plagiosum, and the grey bamboo shark, C. griseum. These sharks are often incorrectly called cat sharks. That common name is more appropriately applied to members of the family Scyliorhinidae. Bamboo sharks are found on coral and rocky reefs and feed on crustaceans, mulluscs, worms, and benthic fishes such as snake eels, lizardfish, goatfish, gobies and flatfish (Dingerkus & Defino, 1983; Randall, 1986; Euzen, 1987). Grey and brownbanded bamboo sharks have transverse bands as juveniles, but these bands fade with maturity and the body becomes a uniform light brown color. In the whitespotted bamboo shark, the juveniles sport a handsome color pattern consisting of a glossy black body peppered with grey spots and saddles. Adults are dark brown overall with beige markings.

Bamboo sharks do well in captivity.The whitespotted bamboo shark has been reported to live for over 25 years in captivity. Several bamboo shark species (including the three encountered in the aquarium fish trade) have been reported to reproduce in public aquaria ( Dral, 1981). The male will grasp the female's pectoral fin and insert a single clasper during copulation. For those unfamiliar with shark anatomy, the claspers are modifications of the pelvic fins that are used to transfer sperm. Mating lasts from five to fifteen minutes. Both the bamboo and epaulette sharks are oviparous. They lay a leathery egg case that has a tuft of filaments on one side that anchor the egg to the ocean floor. In one species, the Arabian carpetshark, C. arabicum captive females laid an average of four eggs at nine day intervals for about six months of the year (Dral, 1981). Although some of the eggs laid were infertile, and a number of embryos did not develop, the majority of the eggs hatched in seventy to eighty days at a water temperature of 24 degrees Celsius (Dral 1981).

Members of the genus Hemiscyllium have nostrils on the end of a short snout, with the mouth nearer to the snout tip than to the eyes, and prominent ridges over the eyes (Compagno, 1984). Unfortunately, only one of the five species comprising this genus is available to US aquarists, the epaulette shark, H.ocellatum.As juveniles, epaulette sharks are adorned with pale bands and spots, but as they grow the bands transform into spots. The color pattern provides effective camouflage, especially when you look down on the shark, and the eye spots (ocelli) over the pectoral fins may function to dupe would-be predators into thinking they are being watched.

The epaulette shark is usually observed at depths no greater than nine meters and often in water so shallow the dorsal fins break the water's surface. On Australia's Great Barrier Reef these sharks are especially common in staghorn coral beds, but can also be found crawling across the reef flat or hiding in tide pools. Juvenile epaulette sharks apparently spend their early years deep in crevices hiding from predators.They are also good at avoiding fish collectors; most epaulette sharks available to the aquarist are over 40 centimeters in length. In nature the adults are most active at night. However, I have observed considerable activity in these sharks during the day, including foraging and mating. They eat small crustaceans, molluscs and worms (Whitley, 1940) which they hunt in reef crevices and extract from the sand. I have observed H. ocellatum shoving its snout into the sand and flipping over pieces of coral rubble to expose concealed quarry.

I had the good fortune to witness the reproductive behavior of this species in the wild on a recent trip to the Great Barrier Reef. In this mating bout, the male bit the pectoral fin of the smaller female and held it in his mouth while she dragged him through the staghorn coral for twenty-nine minutes! While swimming next to her, with her pectoral fin still affixed in his jaws, the male finally succeeded in curling his pelvic region toward hers and inserting a single clasper. Copulation lasted about one and a half minutes. This observation corresponds to reports of captive matings..The shark regularly reproduces in captivity in tanks as small as 135 gallons. This makes it and ideal candidate for captive breeding programs. The eggs, which are similar in appearance to those of the bamboo sharks, are laid at night, two or three at a time, and hatch in about 125 days at 25 degrees Celsius (J. West, personal communication, 1990). Eggs occasionally succumb to fungal infections and the parents have been known to eat the eggs (Whitley, 1967; J. West, personal communication, 1990).

When selecting a tank for your shark remember that adequate surface area is of the utmost importance. For more information on tank selection and filtration see Michael, 1990. Juvenile hemiscyllids can easily be kept in smaller aquaria, even tanks as small as the standard 20 long, but the aquarist must be prepared to provide larger quarters as they grow. At maximum size a bamboo or epaulette shark could be comfortably housed in a 180 gallon tank. Because these sharks, especially juvenile specimens, spend many of the daylight hours hiding in cracks and crevices, they will appreciate secure ledges and caves.Hemiscyllids will dig under rock work to locate food or create a suitable hiding place. Therefore, unstable reef structures can end up crushing your shark. Rocks and coral should be strapped together using nylon wire ties to ensure they will not topple.

As with most reef dwelling animals, these sharks need clean water to thrive. This is particularly true of the bamboo sharks, which appear to be more sensitive to the build-up of dissolved organics and nitrogenous wastes than the epaulette sharks. Bamboo sharks are also more likely to suffer from the shock of acclimation to the tank, and often it may take several days to several weeks before a new specimen starts to feed. For those specimens that are reluctant to eat, try feeding them in the dark. You might also acclimate several mollies to your tank and leave them with the shark to induce a feeding response. Most sharks consume only a small fraction of their body weight in food per week. It is therefore not necessary to feed your shark copious amounts of food. A normal feeding regime for a juvenile hemiscyllid would be to feed it two or three prey items several times a week. Remember, the more you feed your shark, the faster it will grow! Monitor your shark's condition carefully. If it grows at an accelerated rate, feed it less, and if it starts to lose weight feed it more and try different foods.

Nutritional deficiencies are commonly observed in sharks not given a varied diet. Good foods include fish, scallops, shrimp, squid, frozen fish foods and live fish or shrimp. At least once a week it is a good idea to insert a multivitamin tablet in a piece of food of to soak the food in a liquid vitamin supplement. All hemiscyllids have relatively small mouths and teeth suited for grasping, not cutting. hey may have trouble ingesting and chewing large pieces or hard shelled invertebrates. To ensure that the food presented is consumed, chop it into bite sized pieces. When feeding live prey make sure it is small enough to be swallowed whole.

If you decide to keep other fish with your hemiscyllid, choose its tank mates carefully. Stay away from browsing invertebrate predators, such as angelfish, pufferfish, triggerfish and porcupine fish. I have had these fish nip at the body surface and eyes of small sharks, on occasion causing irreparable damage. Although it is possible to keep larger fish, such as groupers, with these sharks, their lightening fast feeding behavior may hamper your attempts to feed the more methodical shark. You can overcome this problem by placing food in a shallow crevice that the shark's tankmates are unable to enter. This gives the shark a competitive edge. It is very proficient at sucking prey from reef interstices. Another technique is to use a feeding stick. I sharpen the end of a three foot piece of rigid tubing and impale the food on the pointed end. I then hold the food several centimeters in front of the shark's nose until the shark moves forward and eats it. In this way, you can monitor just how much food your shark is getting and make sure no food is left to decompose behind tank decorations.

Scavengers such as goatfish and large hermit crabs can perform a functional role in the shark tank by stirring up the substrate and eating scraps of leftover food. Be aware that large bamboo sharks will eat smaller reef fishes kept with them, and bamboo and epaulette sharks will eat ornamental shrimp.

Hemiscyllid sharks are occasionally the victims of parasitic crustaceans such as isopods and copepods. They can be treated with a formalin bath (Moe, 1982) or by introducing a bluestreak cleaner wrasse, Labroides dimidiatus. These wrasses pick crustacean parasites out of the gills and off the body surface of bony fishes and sharks. In the wild I observed a cleaner wrasse inspect and pick at the mouth, barbels, gill slits and body surface of an epaulette shark for over eight minutes.The shark helped by opening its mouth wide and expanding the gill apertures. You may see your bamboo shark turn on its side and chafe against the substrate. If your shark frequently engages in this behavior, treat it for gill parasites.

Bacterial infections, not parasites, are more often the cause of death in captive hemiscylllids. These infections manifest themselves in the form of lesions and extreme redness on the ventral surface and can be treated with chloramphenicol or tetracycline. In another elasmobranch it has been determined that hard calcium substrates such as dolomite and larger grades of crushed coral may irritate the animal's belly and cause infections (Rudloe, 1989). For this reason I prefer to use coral sand in the shark aquarium.

As with the majority of shark species, these animals do not attack people unless provoked. Man, on the other hand, poses a real threat to sharks. There is growing concern about the effect of collection on shark populations. In contrast to most bony fishes, sharks are slow to mature, live long lives and produce relatively few young.. Because of this life history pattern, heavy collection for the aquarium industry may lead to rapid depletion of the population.Therefore, it is important for serious shark keepers to initiate captive breeding programs and to take some of this pressure off natural populations.

References:

Compagno, L.J.V. 1984. FAO Species Catalogue. Vol. 4. Sharks of the World, Part I. FAO Fish. Synop., 125:249pp.

Dingerkus, G. & T.C. DeFino, 1983. A revision of the Orectolobiform shark family Hemiscyllidae (Chondrichthyes Selachii). Bull. Amer. Mus. Nat. Hist. Vol. 176(1):1-93.

Dral, A.J. 1981. Reproduction en aquarium du requin de fond tropical Chilosyllium griseum Mull. et Henle (Orectolobides). Rev. Fr. Aquariol., Vol 7:99-104.

Euzen, O. 1987 Food habits and diet composition of some fishes of Kuwait. Kuwait Bull. Mar. Sci. 1987(9):65-85.

Michael, S.W.. 1990. Sharks and rays in the home aquarium. Aquarium Fish, Vol.3(1):48-57

Moe, M.A.. 1982. The marine aquarium handbook, beginner to breeder. Norns Publishing Co. Marathon, Florida 170pp.

Randall, J.E. 1986. Sharks of Arabia. Immel Publishing, London.148 pp.

Rudloe, J. 1989. Captive maintenance of the lesser electric ray, Narcine brasiliensis, with observations of feeding behavior. Prog. Fish Cult. 5(1):37-41.

Whitley, G.P. 1940. Fishes of Australia, part 1: the sharks, rays and devilfish, and other primitive fishes of Australia and New Zealand. Mosman Royal Society. NSW. 280 pp.

Whitley, G.P. 1967. Sharks of the Australasian region. Aust. Zool. Vol. 14(2):173-188.