The Tasselled wobbegong is one of the 12 extant species of wobbegong sharks from the family Orectolobidae. This shark belongs to the genus Eucrossorhinus, and it is the lone member of this genus.
Tasselled wobbegongs are popular because they are suitable for the home aquarium. They do not grow too large and are typically lethargic like other wobbegongs. Hence, they would not always swim, as such would not require so much swimming space.
This shark species is among the group of carpet sharks with a flattened body, always resting on the seafloor, and with bold bodily markings. Tasselled wobbegongs have so many unique features that will surely capture your curiosity. Of course, you should already be thrilled that they are saltwater sharks yet suitable for the home aquarium.
Naming and Scientific Classification of Tasselled Wobbegong
Apart from the name “Tasselled Wobbegong”, this shark species has other common names such as Ogilby’s wobbegong and bearded wobbegong.
The scientific classification started from the first-ever description of this species in 1867. Peter Bleeker who was a Dutch ichthyologist gave this species the name dasypogon. He derived this name from two Greek words dasys and Pogon which means “hairy” and “beard” respectively. It is obvious he described this species according to its physical appearance. Thus, calling it “hairy beard”.
Bleeker also at the time classified the tasselled wobbegong under the genus Crossorhinus. The genus Crossorhinus is synonymous with Orectolobus (The genus with the highest number of wobbegong species). This classification was valid until 1908 when Charles Tate Regan introduced a new genus Eucrossorhinus for the tasselled wobbegong. He also derived the name from Greek words eu which means “good”, krossoi which means “tassel”, and rhinos which means “nose”.
The main reason for introducing a new genus for this species was the perceived difference in the spacing of the fourth and the fifth gill slits. However, Regan came back later to recheck this feature and then synonymizing Eucrossorhinus with Orectolobus.
In all, the genus Eucrossorhinus of the tasselled wobbegong is considered a synonym of Orectolobus. As a result, authors now choose between the two in which to place this species.
How to Identify a Tasselled Wobbegong
The tasselled wobbegong has typical carpet sharks’ appearance. While lying on the seafloor, they appear relatively flattened. Their head is more flattened than long. The unique feature of the tasselled wobbegong differentiating it from other wobbegongs is the flaps of skin with branches surrounding its head. This also extends toward the chin area of this shark. Another unique trait lies in the coloration and the complexity of its body pattern.
Dermal Lobes
The tasselled wobbegong has a unique branching dermal lobe edging the tip of the snout and extending toward the point where the pectoral fins started. This is one feature that distinguishes this species from other wobbegongs. There is the beard on the chin area and the long barbels on the nostrils. In the nostrils are also grooves that surround the barbels and equally connect them to the mouth.
Head, Mouth, and Jaws
This shark has a large mouth that is in front of the eyes. Just above the eyes are tubercles which is a kind of protrusion that exists no other place in the body of the shark. Then, there are spiracles (breathing holes) positioned behind the eyes.
On the lower jaw are furrows that run from the corners of the mouth and along the middle of the jaw. This shark species also has five pairs of short gill slits.
Dentition
On the upper jaw of the tasselled wobbegong are about 26 tooth rows, while on the lower jaw are about 19 tooth rows. The examination of each tooth shows a narrow, pointed cusp. There are also characteristically long teeth that appear like fangs in the symphysis of both the upper and the lower jaws. The upper jaw contains 3 rows of symphysial teeth, while the lower jaw contains 2.
Fins
The tasselled wobbegong has all the fins expected of a shark. However, the caudal fin is with only the upper lobe lacking a lower lobe. The largest of all fins are the pectoral fins followed by the pelvic fins. These fins are rounded in shape.
This shark has two dorsal fins with the first noticeably larger than the second. The second quarter of the pelvic fin marks the origin of the first dorsal fin. The dorsal fins are a little bit tall and have short bases. On the opposite side of the second dorsal fin is the origin of the anal fin which is small and just about half the size of the second dorsal fin.
Just after the pelvic fins, the body of the tasselled wobbegong tends to narrow down toward the peduncle of the tail. The upper lobe of the caudal fin has near its tip a strong notch located on the anterior side of the shark. Also, the caudal fin is just typically short.
Coloration
The tasselled wobbegong has a complex body color combination. However, the base color is usually brownish and sometimes with a tint of yellow or gray. On this base color on the backside of this shark is a pattern resembling a mosaic of several unified small, dark spots. Sometimes, there are lines and even bands of darker colors present.
The underside of this shark species is generally white in color. Though, the color pattern tends to reach toward the underside of the caudal fin, and also the margins of the pectoral and pelvic fins.
Growth Size
The tasselled wobbegong does not grow large in size, as a result, the maximum length expected of this shark species is about 4 feet (1.22 meters). This size, coupled with the sluggishness of the species and their level of adaptation makes them suitable for home aquaria.
Where to Find Tasselled Wobbegongs
This shark species is a bottom-dweller that prefers to inhabit shallow waters of coral reefs. They are most common in coral heads, reef channels, and faces. Tasselled wobbegongs occur both near the shore and in open sea from water depths of 6 feet (1.83 m) up to 160 feet (48.77 m).
Their habitat range covers the tropical waters in the southwest Pacific Ocean. This includes northern Australia, New Guinea, and off the coast of Indonesia. There are reports of tasselled wobbegongs in other locations such as Malaysia, however, there is still ongoing research to confirm the distribution and population of this species worldwide.
Typical Behavior of the Tasselled Wobbegong
Wobbegong sharks are generally lazy and sluggish, so is the tasselled wobbegong. This species is solitary and spends most of its day time lying flat under the reef of inside caves. Their body pattern helps them to camouflage against their hideouts.
When hiding, tasselled wobbegongs tend to curl their tails. More so, they engage actively in opportunistic feeding as they rest. There are also indications that this species engages in the active luring of prey. They do this by continuously waving their tails to imitate the movement of small fish. Hence, any unsuspecting fish or invertebrate nearby that approaches this shark is used as a meal.
These sharks on their own choose favored spots for resting. They also tend to maintain fidelity to these resting spots. Even when the move, they do not move too far from these spots.
Feeding Behavior
The tasselled wobbegong is more active at night. Therefore, whenever it is dark, it tends to come out from the resting position to actively hunt for prey. As they emerge, they swim toward the reef to forage for food. Then, as dawn approaches, these sharks tend to return to their respective defined home ranges.
The food range of this species includes crustaceans, cephalopods, and bony fishes. Examples of fish that make prey for the tasselled wobbegong are Bamboo shark (Chiloscyllium punctatum), squirrelfish, soldierfish, sweepers, and others. These are schooling fish that may share the same cave or hiding spot with this shark species.
They can as well get prey during the day through ambush predation.
Adaptations of the Tasselled Wobbegong
Excellent Camouflage
The tasselled wobbegong with its complex color pattern and dermal margins can perfectly camouflage against its resting area. Though this species may be more sluggish than the sister species, it is seen as the most specialized. This characteristic helps this shark during ambush hunting and when hiding away from predators.
Active Luring Technique
This shark is also popular for its characteristic luring behavior. The tasselled wobbegong can wave its tail to and fro in a slow movement. This shark starts this behavior once it senses prey nearby. Most of all, the tail has the appearance of a small fish. Hence, the prey unknowingly gets within the striking range of the shark where it uses it as a meal.
Tactful Resting Position
Even while the tasselled wobbegong is resting, it keeps its head in an elevated position to be ready for an attack. This implies that this shark is actually anticipating the approach of any prey it could lure. Thus, the elevated head keeps it in a striking advantage.
Do Tasselled Wobbegongs Have Any Parasites?
The tasselled wobbegong just like other shark species has several parasites attaching to them. For example, the tapeworm Parachristianella monomegacantha is a common parasite of this species. Also, the blue streak cleaner wrasse (Labroides dimidiatus) and cleaner shrimp associate with this species.
Life Cycle and Reproduction
It is unclear the size at which tasselled wobbegongs attain sexual maturity. However, an individual that is 4 feet (1.22 m) long is already sexually matured. These sharks mate and give birth to their young ones alive. That is to say, just like other wobbegong species, this shark is also ovoviviparous.
The developing embryos get nourishment from the yolk sac until birth. They usually birth inside caves with their pups measuring just about 8 inches (20.32 cm) in length.
Tasselled Wobbegongs and Humans
Threat to Humans
The tasselled wobbegong in general poses no threat to humans. But, this shark can inflict painful bite injuries on humans with its sharp teeth. Of course, humans may unsuspectingly approach this shark when it is camouflaged and get bitten.
Attacks on Humans
There are records of attacks on humans by this shark species. Notably, many of these attacks are unprovoked. Of all wobbegong species, the tasselled wobbegong proves to be more aggressive.
Though this shark species can inflict very painful injuries, it may not cause fatal injuries to humans. Their jaws tend to lock up once they bite and are often difficult to separate. Therefore, claims of this shark killing people is still unconfirmed.
Captivity
The tasselled wobbegong does well in captivity. They occasionally come to the aquarium trade. Some hobbyists keep this shark in a home aquarium may be due to its elaborate color patterns. In all, they adapt as captive species and do not require so much care in terms of feeding and others.
Ecotourism Attraction
The tasselled wobbegong also serves as an ecotourism attraction. Several divers go too close to this species underwater and come out without attack incidents. However safe this may appear, humans are advised to take caution when near this shark. They do not have excellent vision and may mistake a close movement as prey, hence attacking.
On the other hand, they prefer to stay in concealed areas, thus may be provoked unknowingly leading to nasty bites.
Economic Value of Tasselled Wobbegong Sharks
This shark species do not have much economic value. Their skin due to its colorful complex pattern serves as raw material for making leather. Also, they participate in the aquarium trade. Aside from these, tasselled wobbegongs rarely have other economic value.
Conservation
The International Union for Conservation of Nature (IUCN) listed this species (Eucrossorhinus dasypogon) as “Least Concern (LC)” in their Red List of Threatened Species.
The assessment is a result of the fact that the tasselled wobbegong is not a regular victim of heavy fishing. Moreover, they are conserved in aquaria as captive species. In waters surrounding Australia, there is no fishing of this shark, hence, they are free from heavy threat.
However, this shark species may suffer negatively from extensive fishing activities in other regions where it occurs. Degradation of their habitat due to human development leading to the removal of coral reef and pollution also affect this species negatively.
10 Amazing Facts of the Tasselled Wobbegong in a Glance
1. The Genus Name Eucrossorhinus is a Synonym of Orectolobus
After the classification of the tasselled wobbegong into a new genus Eucrossorhinus, the trait for the classification was reconsidered. Therefore, the new genus was synonymized to the genus Orectolobus
which is the genus with the highest number of wobbegong species. As a result, authors may decide to stick with the new genus or go with Orectolobus. This trait is the distance between the 4th and 5th gill slits.
2. The Tasselled Wobbegong is the Only Species in Its Genus
This shark is the lone species in the genus Eucrossorhinus. Hence, its specific name is Eucrossorhinus dasypogon. The genus is one of the three genera in the family of Orectolobus consisting of wobbegong sharks.
3. This Shark Has the Most Elaborate Color Pattern of All Wobbegongs
The complex color pattern of the tasselled wobbegong extends even to the underside of the tail fin and the edges of the pectoral and pelvic fin. Though the belly side is just plain white. This color pattern consists of small dark spots, lines, and bands arranged in the form of a mosaic. Moreover, the arrangement is fine and unique.
4. The Tasselled Wobbegong is a Lazy Species
A typical wobbegong shark is lazy and sluggish. Thus, the tasselled wobbegong would rest throughout the day lying flat on the seafloor and inside rocks. They rarely engage in active swimming, however, they are more active at night. During dark hours, they come out to actively hunt for prey. Hence, this shark species are considered nocturnal due to this behavior.
5. The Tasselled Wobbegong is an Ambush Predator
This shark with the help of its body pattern conceals itself in its resting place laying an ambush for potential prey. They blend in with their environment waiting for prey to come within their striking range to attack.
6. This Shark Species Engages in Active Luring
Once the tasselled wobbegong could sense a prey close, it begins to wave its tail trying to mimic small fish. This activity makes the unsuspecting prey to come closer, hence, the shark attacking subsequently.
7. Tasselled Wobbegongs are Known For Their Aggression Amongst Other Wobbegongs
Out of the 12 extant species of wobbegongs, the tasselled wobbegong is notable for exhibiting a higher level of aggression. As a result, it has several records of unprovoked attacks on humans.
8. The Tasselled Wobbegong Can Inflict Severe Injury With Its Sharp Teeth
While this shark is generally not considered a threat to humans, their bite can cause a severe and painful injury. Above all, once they bite, they hardly disengage and the jaws are difficult to separate.
9. One Unique Feature of the Tasselled Wobbegong is the Dermal Flaps Surrounding Its Snout
This is the physical trait by which the tasselled wobbegong differs from other wobbegongs. This edge of branching dermal lobes reaches toward the chin. It is a physical feature easily noticed and distinguishes the tasselled wobbegong. Due to this feature, the tasselled wobbegong appears heavily “bearded”.
10. Tasselled Wobbegongs are Notable Species in the Aquarium Trade
Of all wobbegong species, the tasselled wobbegong and Ward’s wobbegong adapts better to home aquarium. This is because these species do not grow as large as others. Also, coupled with the general lethargic behavior of wobbegongs, they do not require much space to thrive. Even more, feeding the tasselled wobbegong is not a demanding task, thus, they can be fed only twice a week and that will be all. This is possible due to this shark’s slow rate of metabolism.
Further Reading
- “Eucrossorhinus dasypogon, Tasselled Wobbegong”, Fish Base.
- “Discover Fishes: Eucrossorhinus dasypogon, Tasselled Wobbegong”, Florida Museum of Natural History
- “Tasselled Wobbegong (Eucrossorhinus dasypogon)“, IUCN Red List of Threatened Species.
- “Tasselled Wobbegong”, Wikipedia (assessed May 18, 2020).