The Epaulette Shark is one of the fishes sampled in fish stores for aquariums. And, most people may describe it as the best pet shark for fish tanks. As a result, here are the facts you must know about this aquarium beauty.
The Epaulette Shark Background
There are 6 species of sharks that make up the genus (Hemiscyllium) of the Epaulette sharks. And, all are from the family Hemiscylliidae.
However, the only species that you are likely to see in the fish store is the Hemiscyllium ocellatum. This is so because the other species rarely occur in nature. Most of all, the places they are found, there is little or no freedom to collect fishes.
For Example, we have Hemiscyllium freycineti. These handsome species are from Irian Jaya.
The other Hemiscyllium species scattered around the coast of Papua New Guinea. And these places, there are no collection of fishes.
While all the species of Epaulette sharks have similar characteristics, this page focuses more on the Hemiscyllium ocellatum. This species commonly obtained through aquarium trades.
The Epaulette Shark (Hemiscyllium ocellatum) in Nature
Species: H. ocellatum
Binomial Nomenclature: Hemiscyllium ocellatum
At first, Pierre Joseph Bonnaterre a French naturalist described this species as Squalus ocellatus. This was in 1788 published in the Tableau encyclopédique et méthodique des trois regnes de la nature. And, the author is Charles Joseph Panckoucke.
But later on, the current name still in use today Hemiscyllium ocellatum was adopted.
The evolutionary development of the Hemiscyllium (genus) shows that they are polytomy (Goto 2002, morphological analysis). Thus, implying that there was no clear resolution of the relationship between the epaulette shark and the sister species into dichotomies.
The Epaulette Shark otherwise called the “walking shark” is a species of carpet sharks with an elongated tail. Normally, you will find this group of sharks in shallow tropical waters. Commonly on the coast of New Guinea and Australia.
Just like the military epaulettes, there are two large black spots circled by white marks behind the pectoral fins of this shark species. Hence, the name Epaulette sharks.
These species are not likely to grow much big. In fact, they are relatively small in size. As such, you will commonly see Epaulette sharks below 39 inches (below 1m) length on maturity.
This relatively small size is one of the reasons this shark is perfect as home aquarium pets. Another reason is its ability to adapt to confined spaces. As such, shark keepers do not require a very large tank to house the Epaulette shark.
With their slender body shape, these sharks can swim comfortably. However, they much likely prefer to walk with their paired muscular fins around the bottom of their habitat. The fins help to push them while they wriggle through coral reefs. Hence, the name walking shark.
When seeking for food, they will usually visit tidal pools. And, they can survive quite long outside water.
This species is under the IUCN – International Union for Conservation of Nature list of Least Concern fishes. Well, fishers do not see their economic significance. Of course, except for their participation in the aquarium trade.
Where to Find the Epaulette Sharks
The Epaulette shark species are distributed along the coast of Papua New Guinea (the southern part of New Guinea.
This extends through the northern coast of Australia. And, spreads far to the south reaching Sydney.
A large number of the Epaulette shark species inhabit the Capricorn-Bunker Group of the Great Barrier Reef. Thus, having thousands estimated to live in the reefs surrounding Heron Island.
Other places you are likely to find the Epaulette sharks include Solomon Islands, Malaysia, and Sumatra. Although, the claims of these species living these places are yet to be verified.
Why Do Epaulette Sharks Prefer to Inhabit these Zones?
These fish species prefer to live in the coral reefs, tidal pools, and staghorn coral stands. In other words, they prefer shallow water bodies.
As such, the maximum water depth in which you can find the Epaulette sharks is 160 ft. (50 m). Mostly, you will see them in waters only just deep enough to cover their bodies.
Now, these shallow waters conducive for the Epaulette sharks are available in the locations mentioned above. Thus, the reason Epaulette sharks inhabit the zones.
Physical Characteristics of the Epaulette Sharks
The Epaulette shark has a long slender body. And, more than half of the body is the caudal peduncle.
An adult Epaulette shark has a cream or light brown body base color. There are many brown spots through the body of the shark. Although, the spot has wide gaps between them.
When still juveniles, there are more light and dark bands which alternate their body over. However, as they grow the bands break apart.
Above the pectoral fins are two large black spots circled in white (false eyespots). The name Epaulette comes from this characteristic.
The shark has a round and short snout. They have nares barely at the tip of the snout with grooves running toward the mouth. Also, at the tip along with the nares is a pair of nasal barbells quite tiny though.
In the upper jaw of the Epaulette sharks lies a row of 26 to 35 teeth. On the other hand, the lower jaw contains a row of 21 to 32 teeth. The teeth in question appear quite small. they have wide bases and cusps triangular in shape.
The shape of the eyes is obviously oval. They appear elevated. Also, below each of the eyes is a large spiracle.
The Epaulette sharks possess five pairs of gill slits. But, these are small and the 4th and 5th gill-slits are the closest to each other.
The pelvic and pectoral fins have thick muscles enabling them to push their bodies as they walk. More so, they are rounded and broad.
On the back of the shark’s body are two dorsal fins. There is a space between the two fins. Furthermore, they appear similar in size.
There is also the caudal fin which only has an upper lobe and no ventral lobe. And, this upper lobe has a well pronounced ventral notch located close to the tip. More so, the notch has an angle that relates to the body in an almost horizontal manner.
The last is the anal fin which comes right ahead of the caudal fin.
The Adaptations of the Epaulette to Survive its Habitat
Adaptations for Movement
The Epaulette sharks move around in reefs through the process of walking. They use their muscular pectoral and pelvic fins which also has the shape of a paddle to push aside substrates along the way.
By doing so, they push their bodies as they wriggle it through the coral reefs.
Certainly, this shark species can swim when in deep water. However, as a preference, they will always find their way to the coral or sandy bottom where they can walk.
In comparison with other shark species, the Epaulette sharks have a separated and reduced cartilaginous supports for their pair of fins. This lets them turn the fins to serve as limbs.
When they move in such a crawling manner, they can readily move out of deep waters. As a result, they can access a more convenient tidal pool.
Adaptation for Common Activity
The majority of the Epaulette sharks’ activities are in low water. And, they are relatively nocturnal.
They may mostly hide below or in coral heads. Although, their hiding just like the Ostrich may only involve their head. Thus, hiding the head and exposing the rest of the body.
At times, when observed the sharks will rest on sandy flats. Or, on top of reefs facing toward the water current. This positioning in biology is rheotaxis. And, the sharks may get improved respiration and be more conscious of predators.
Adaptations for Escaping Predation
The Epaulette sharks are prey to larger fish species which includes other sharks. Therefore, to protect themselves, they possess coloration which serves as camouflage.
The epaulette of the shark which includes two fake eye spots are believed to distract and deter predators.
However, the Epaulette shark is prone to parasite attacks. The gnathiid in its larval stage (praniza) is the major parasite of this species of sharks.
Hence, the praniza attach mostly to the body of the shark around the claspers and cloaca. Although, sometimes they also attach to the gills and mouth of the shark.
But then, these parasites may not be extremely harmful to the shark’s health. Instead, they only cause negligible damage to the shark. This includes feeding on blood.
Other parasites are attacking the Epaulette sharks in different parts of their bodies. For example, the ostracod Sheina orri that attaches to the gills, myxosporean species of the genusKudoa that attaches to the muscles of the skeleton, the Proleptus australis (nematode) that infests the stomach, and the Hemogregarine protozoan (Haemogregarina hemiscyllii) this one infects the blood.
Response to Low Oxygen
During the low oxygen conditions known as hypoxia, the shark’s heart rate and ventilation lower immediately.
Also, the vessels carrying blood dilates sending extra blood to the brain and heart. This leads to a fall in the blood pressure of the shark.
Furthermore, the Epaulette shark reduces the rate of metabolism of special areas in the brain. An example of this is the deactivation of the motor nuclei while the sensory nuclei remain functional.
The reason for this action is to lower energy demand. As such, supplying ATP enough to keep the neuron alive.
While undergoing all these processes the Epaulette shark does not completely shut down. Instead, it remains alert to its surroundings in case of danger.
The hypoxic conditions are most likely to occur in shallow reefs where the Epaulette sharks inhabit.
This happens at night through the action of receding tides. As such, the reef isolates from the ocean causing a drop in the level of dissolved oxygen.
This drop can be up to 80% or more. Of course, the extra could result from the oxygen usage (through respiration) by organisms inhabiting the pool.
Well, the Epaulette sharks have adaptations that enable them to survive very low oxygen conditions for several hours. And, will not lose behavioral responsiveness.
To track down its prey, the Epaulette shark makes use of its well-developed olfactory and electro-receptive senses. As such, even when the prey is in hiding, the shark can be able to locate it.
The Epaulette shark will suck prey into its mouth. It does this by expanding its buccal cavity.
Sometimes, this shark species while in search of food can turn debris over, using its snout. And also, it can thrust its head into the sand to swallow prey under the sand. While doing this, it expels the sand through its gill slits.
The Epaulette shark can chew food between 5 to 10 minutes. More so, it can depress its teeth forming a flat surface used to crush prey with a hard shell.
Being a bottom feeder, the Epaulette shark feeds on small invertebrate crustaceans that live on the seafloor. Others include small bony fishes and worms.
They can feed at any time of the day as they get prey. Thus, this shark species are opportunistic predators.
The Epaulette sharks living off Heron Island feed mostly on annelid worms usually from the class Polychaeta and crabs.
The juveniles will feed mostly on the worms. However, as they approach adulthood, they prefer more crabs.
The Epaulette sharks conveniently mate in the wild within the period from July to December. Usually, the male shark will follow the female and sometimes bite it to initiate courtship. At times, females may try to put up some form of resistance.
During the process of copulation, the male uses its mouth to hold onto the female’s pectoral fin. Then, it lies alongside the female and inserts one of his claspers into the female’s cloaca. This may last for about two minutes.
The Epaulette shark is oviparous. Thus, the females will lay eggs from August to December.
The female sharks will drop the eggs in capsules of 2 at a time usually every 14 days. Although, in rare events, the egg capsules will be up to 4.
The size of an egg capsule is 3.9 inches (10 cm) long and 1.6 inches (4cm) wide. After a period of 120 to 130 days, the eggs will hatch and the young sharks will emerge.
The juveniles will usually start at a length of about 5.5 to 6.3 inches (14 to 16 cm). At first, they grow quite slowly. However, after 3 months the growth rate will increase.
At about 7 years, the sharks will attain a length of 21 to 25 inches (54 to 64 cm). Now, both male and female have matured sexually. As a result, one can call them adults.
Epaulette Sharks and Humans
People who go to the beach will usually observe this shark species. Of course, the sharks will come out of the water and will move slowly back in.
Generally, they do not show noticeable fear for humans. And, they do not cause harm to them. However, the shark might bite those who go about handling it.
Another thing is, the sharks often sustain injuries from human handling.
The Epaulette shark species are good for aquariums. Certainly, they adapt to captivity. As a result, you can easily find these sharks in public aquariums anywhere in Canada, the United States, and Australia.
Aquarium Care Sheet for Epaulette Sharks
- Max. Size : 42 inches (107 cm)
- Size of Tank Required: 135 gallons (510 liters) and above.
- Suitable Tankmates: Not a community shark species. Any tank mate will either be a threat or feel threatened.
- Optimal Tank Temperature : 72 to 82 F.
- Water Ph: 8.1 to 8.4
- Water Type: Marine water (Saltwater)
Take Note of These While Caring for Your Epaulette Sharks
Tank Growth Size
The growth size of an Epaulette shark in a tank is not different from those in the wild. As such, expect your pet shark to likely grow up to 42 inches.
However, most at maturity will be under 39 inches.
The Epaulette shark does not require so much tank space. Therefore, a tank as small as 135 gallons can house your pet shark as it breeds.
But then, it is always better if you choose a larger tank of about 180 gallons for a single Epaulette shark at a maturity age.
To make your pet shark feel safe and comfortable just like in its natural habitat, make use of aquascapes.
Add safe caves and ledges to the aquarium. Surely, your pet shark will appreciate it since they like hiding in cracks and crevices. Especially, during daylight.
Make use of sand as the substrate element. The Epaulette shark will dig into the sand searching for food or hiding place.
Also, add some aquarium plants into the tank.
Always avoid unstable reef structure and a very coarse substrate. These will cause injury to the shark.
If you are planning to keep a community tank, the Epaulette shark may not be the shark you need.
This shark species is a predator and will end up preying on other smaller fishes.
On the other hand, if you place other larger shark species, they may feed on the Epaulette shark.
Other bony fish tankmates will always harass your pet shark causing injuries to it.
Even when placed together with its species, the males especially will behave aggressively toward each other. And, may even harass females. This is rampant in small tanks.
These sharks are better left alone. However, if need be you have two Epaulette sharks in a tank, choose two females.
Or, if you want to keep breeding mates, use a very large tank of a male and one female or more. Then, be ready to separate the fishes after mating if you notice persistent harassment of the females by the male.
Chances are your pet sharks may not start feeding immediately you introduce them into the tank. If so, you need to encourage them by offering tiny pieces of cleaned squid.
Afterward, you can now introduce shrimps, scallops, small fishes, worms, and crabs.
Feed the Epaulette sharks prey materials several times in a week. It does not have to be regular.
If your shark tends to lose weight, give it more to eat.
Also, make sure you chop the food materials in smaller pieces that can enter the shark’s mouth once. If not, it may find it difficult to chew larger food materials.
The Epaulette shark’s expected lifespan is up to 20 to 25 years. Hence, ensure you are capable of keeping this shark species as a pet for such long before choosing it.
While setting up breeding colonies of Epaulette sharks, note that the adult sharks may sometimes eat the eggs.
As such, try to incubate the eggs in a separate tank. For example, the aquarium sump.
Be sure that the Epaulette shark is a marine water fish and avoid putting it in a freshwater aquarium.
All the descriptions and advice provided on this page will give you a head-start as you plan to keep an Epaulette shark. Certainly, you will learn more as you proceed.
You can always keep this as a reference sheet. And also, do not forget to compare other Aquarium sharks before you set out to Purchase tank items for an Epaulette shark.