TASSELLED WOBBEGONG
Camouflaged master ambushing prey as it lures the prey into striking range
The Tasselled wobbegong (Eucrossorhinus dasypogon) is a shark belonging to the family Orectolobidae and the only member of its genus. It inhabits shallow coral reefs off northern Australia, New Guinea, and surrounding islands. It is one of the longest members of its family with recorded lengths of over 4 feet and even some reports of one reaching 5.9 feet in length, though this is not confirmed. Its most distinctive trait is a fringe of branching dermal flaps around its head, which extends onto its chin. The fringe, along with its complex color pattern of small blotches and reticulations, enable it to camouflage itself against the reef environment. They are nocturnal, solitary ambush predators who are masters of disguise, tricking unknowing prey.
Family: Orectolobidae – Wobbegongs
Genus: Eucrossorhinus
Species: dasypogon
Phylum– Chordata
Class– Chondrichthyles
Common Name– Carpet Sharks
Family– Orectolobidae
Common Name– Wobbegongs
Genus– Eucrossorhinus
Species– dasypogon
Status: IUCN Red List LEAST CONCERN
Average Size and Length: They are born around 20 cm/ 7.8 inches. Mature males are around less than 117 cm/3.8 feet. The maximum recorded has been over 125 cm/ 4.1 feet. There have been some accounts of a Tasselled wobbegong reaching 5.9 feet in length, but this is unconfirmed.
Current Rare Mythical Sightings: The Tasselled wobbegong was originally described by Dutch ichthyologist Pieter Bleeker in an 1867 volume of Archives Néerlandaises des Sciences Exactes et Naturelles. His explanation was based on two Indonesian specimens, one caught off Waigeo and the other off Aru. He gave it the name dasypogon, from the Greek dasys (“hairy”) and pogon (“beard”), and assigned it to the genus Crossorhinus (a synonym of Orectolobus). In 1908, Charles Tate Regan created the new genus Eucrossorhinus for this species, derived from the Greek eu (“good”), krossoi (“tassel”) and rhinos (“nose”). Regan then reassessed the main trait he used to separate Eucrossorhinus (the spacing of the fourth and fifth gill slits) and synonymized it with Orectolobus. Later authors have placed the Tasselled wobbegong either in its own genus or in Orectolobus.
A 2009 phylogenetic analysis based on mitochondrial and nuclear DNA found that the Tasselled wobbegong was basal to all other wobbegongs, except the Northern wobbegong. This result supports the synonymization of Eucrossorhinus with Orectolobus. Molecular clock estimation placed the speciation of the Tasselled wobbegong at 11–6 Ma, coinciding with a period of significant geological rearrangement and the formation of coral reef habitats in the region.
Teeth and Jaw: The large mouth is positioned ahead of the eyes, almost at the end of the head. There are furrows on the lower jaw extending from the mouth corners and along the jaw median. There are 23–26 upper and 19 lower tooth rows. Each tooth has a single slender, pointed cusp. The 3 upper and 2 lower rows of symphysial teeth are especially long and fang-like, perfect for grasping its prey.
Head: It has a broad and flattened head and wider than it is long. The nostrils have long, branching barbels, and have grooves surrounding them and connecting them to the mouth. There are tubercles above the eyes but not elsewhere, and behind the eyes are larger spiracles. The 24 to 26 pairs of dermal lobes located on the sides and front of the head are highly branched and form a more-or-less continuous fringe from the tip of the snout to the pectoral fin bases.
Denticles: There are many highly branched dermal lobes on the head and on the “beard” that is on the chin.
Tail: Behind the pelvic fins, the body rapidly tapers to the short caudal peduncle. The caudal fin is short, with no lower lobe and an upper lobe bearing a strong ventral notch near the tip.
The Tasselled Wobbegong has a cleaver trick. At the end of the tail is almost a fish-shaped lure in which it waves back and forth, mimicking a swimming fish. Luring its prey has never been so easy.
Demographic, Distribution, Habitat, Environment and Range: The Tasselled wobbegong can be found in the southwest Pacific in Indonesia in Waigeo and Aru, and in New Guinea and Australia. There are questionable accounts in Malaysia. They can be found inshore over coral reefs in the coral heads, channels and reef faces to about 160 feet deep. Their home range is more than likely small.
Diet: They feed on bottom fish and possibly invertebrates. They catch nocturnal fish by sharing its cave and ambushing prey. There has been an account of a Tasselled wobbegong consuming a 3.3-foot Brownbanded Bambooshark.
Observations in captivity have further revealed that this species seems to engage in active luring behavior. When it perceives food nearby, it begins to slowly wave its tail back and forth; its caudal fin resembles a small fish, complete with a dark eyespot at the base. The shark typically rests with its head elevated, which places it within striking distance of any prey drawn by its tail.
Ram-Suction Index: They are high on the RSI, sucking in and impaling prey on their large teeth.
Aesthetic Identification: The Tasselled wobbegong is a master of camouflage. It has a reticulated pattern of narrow dark lines on a light background. There are scattered symmetrical, enlarged dark dots at the line junctions with indistinct saddles. They are white ventrally. The body is broad and flattened overall. The five pairs of gill slits are short. There are very broad, paired fins. The pectoral and pelvic fins are large and rounded. The dorsal fins are short-based and fairly tall. The first dorsal fin is slightly larger than the second dorsal fin and originates over the latter quarter of the pelvic fin bases. The anal fin originates behind the midpoint of the second dorsal fin and is no more than half its size.
Biology and Reproduction: Their biology is mostly unknown. Their reproduction is presumably ovoviviparous. Sexual maturity is uncertain.
Cleaner shrimp and a the Bluestreak Cleaner wrasse have been seen attending the Tasselled wobbegong. The tapeworm Parachristianella monomegacantha is a known parasite of the Tasselled wobbegong.
Behavioral Traits, Sensing and Intelligence: The Tasseled wobbegong is nocturnal. They rest by day with a curled tail on the bottom in caves and under ledges. They are more than likely solitary. They have the ability to remain out of water for long periods of time. Individual Tasselled wobbegongs tend to remain within a local area and have favored resting spots. While resting, it opportunistically ambushes nearby fishes and invertebrates, and also lures in prey by waving its tail to mimic the appearance of a small fish. At night, it emerges and actively forages for food. They are thought to have poor vision.
Speed: They are more than likely a slow swimmer. They use their paired fins to crawl around on the bottom and even out of water. They can remain motionless during the day.
Tasselled Wobbegong Future and Conservation: They are considered near threatened in most of its range due to reef destruction and the ongoing threat by commercial fisheries. They are of least concern in Australia. Its skin is occasionally used for leather because of its attractive qualities.
Tasselled Wobbegong Recorded Attacks on Humans: They are potentially dangerous to humans if provoked, but generally aren’t dangerous. Their bite is particularly hazardous. They have many small but sharp teeth and their bite can be severe. There have been some reports of wobbegongs who have attacked swimmers, snorkelers and SCUBA divers who inadvertently come close to them. Tasselled wobbegongs in particular have been reported to bite divers.
The Australian Shark Attack File contains more than 50 records of unprovoked attacks by wobbegongs, and the International Shark Attack File 28 records; none of them fatal. Wobbegongs have also bitten surfers. Wobbegongs are very flexible and can easily bite a hand, while a person is holding onto their tail. They can bite through a wetsuit. They have been known to hang on and they can be very difficult to remove.