Spotted wobbegongs sense their environment with both chemical and visual cues. The only form of communication yet documented among spotted wobbegongs takes the form of chemical pheromones released by females during the breeding season (Eagle, 2005). Females use the pheromones to attract potential mates.
Most sharks are capable of sensing their environment through electroreception. Most have electrosensors called ampullae of Lorenzini situated in clusters around the head that can sense the weak electrical currents associated with the functioning of nerves and muscles of living animals (Carrier, 2005). The presence of these ampullae in spotted wobbegong has yet to be confirmed, but it is presumed they possess electroreception capabilities.
Communication Channels: chemical
Perception Channels: visual ; chemical ; electric
The average spotted wobbegong ranges in length between 150 and 180 centimeters (59-71 inches) in total length. Males usually mature at around 60 centimeters (24.6 inches). The largest recorded spotted wobbegong was measured at 360 centimeters (126 inches). At birth, the average newborn is 21 cm (8.3 inches) (Eagle. 2005).
Spotted wobbegongs belongs to the Order Orectolobiformes, commonly called carpet sharks because of their ruffled, rug-like appearance (Dewey et al., 2005). The coloration pattern of spotted wobbegongs provides camouflage against the varying color patterns of the environment it inhabits. They are generally a pale yellow or green-brown with large, dark areas down the midline of the body. White "O"-shaped spots often cover the entire back of the shark. Although other species of Orectolobidae family are usually similar in appearance, the coloration pattern of spotted wobbegong is distinctive (Eagle, 2005).
Besides the distinctive color pattern, spotted wobbegong are easily identified by their flattened heads, possessing six to ten dermal lobes below and in front of the eyes, and having long nasal barbels around the mouth and on the sides of head (“UN Atlas of the Oceans”, 2005). The barbels are sometimes branched basally. The mouth lies in front of the eyes with two rows of fang-like teeth in the upper jaw and three in the lower jaw. Spotted wobbegongs can also be characterized by their large spiracles, a lack of dermal tubercles or ridges on the back, a symphisial groove on the chin, and nasoral and circumnarial grooves. The dorsal fins are spineless and the first begins over the pelvic base with the anal fin originating behind the second dorsal fin. The pectoral and pelvic fins are large and broad, and the caudal fin is much shorter than the rest of the body (Compagno, 2002).
Range length: 60 to 320 cm.
Average length: 165 cm.
Average basal metabolic rate: unknown cm3.O2/g/hr.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Little is known about the lifespan of spotted wobbegong. However, based on information about sharks in general, it is presumed that spotted wobbegong are relatively long lived animals. They fall prey to only a few predators, outside of humans, and,, as long as sufficient prey is available, spotted wobbegongs should live long, healthy lives.
Spotted wobbegong are bottom-dwelling sharks found in marine environments ranging from temperate to tropical. Their main habitat consists of inshore areas near the continental shelves, from the intertidal zone down to depths of 110 meters (Pollard et al, 2003). More specifically, spotted wobbegong inhabit coral and rocky reefs, estuaries, seagrass beds, coastal bays, and areas with sandy bottoms. They are a primarily nocturnal species, and are found in caves, under the overhangs of rocky and coral reefs, and in shipwrecks during the day. Juveniles are commonly found in estuaries and seagrass beds. There has been limited evidence for site attachment, and it is quite common to find a spotted wobbegong in water barely deep enough to cover its body (Eagle, 2005).
Range depth: 0 to 110 m.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: benthic ; reef ; coastal
Other Habitat Features: estuarine ; intertidal or littoral ; caves
Spotted wobbegong are generally found in inshore waters off the southern and southeastern coasts of Australia, from the Fremantle region in Western Australia to Moreton Island in southern Queensland (Pollard et al, 2003). Some sources indicate that spotted wobbegong have a global distribution that includes Japanese waters and the South China Sea (Eagle, 2005). However, the World Conservation Union states that these records are probably incorrect and are most likely the result of difficulty in distinguishing spotted wobbegong from other, closely related, species. If so, spotted wobbegong should be considered endemic only in the Australian regions described above (Pollard et al, 2003).
Biogeographic Regions: pacific ocean (Native )
Spotted wobbegong, like most sharks are carnivorous and feed primarily on bottom dwelling invertebrates (Compagno, 2002). Their invertebrate prey includes crabs, lobsters, and octopus (Campbell, 2005). Spotted wobbegong also prey on some bony fishes inclusing Serranidae (sea bass), Scorpaenidae (scorpionfishes), and Kyphosidae (luderick). They may also prey on other, smaller shark species, including individuals of their own species, as well as some ray species.
Spotted wobbegong appear to feed primarily by sitting and waiting for unsuspecting prey that may even nibble on the shark’s dermal lobes before the shark will strike (Compagno, 2002). It is believed that the short broad mouth and large broad pharynx aids in sucking in prey. Based on video footage, prey is sucked into the mouth as the pharynx opens and water rushes in. This feeding mechanism in spotted wobbegongs is very similar to that of Squatinidae (angel sharks) except that the prey in angel sharks is taken from above as opposed to in front of the mouth as it is in spotted wobbegong.
Spotted wobbegong are more specialized for jaw protrusion than are most other shark species (Wu, 1994). The palatoquadrate and Meckel’s cartilage project anteriorly and are the major component of protrusion. The movement of these two components simultaneously enlarges the oral cavity to generate the majority of the suction forces. This extra protrusion and enhanced suction force combined with the powerful jaws and multiple rows of enlarged fang-like teeth in the upper and lower jaw (Compagno, 2002), form a deadly trap that spotted wobbegongs use to impale and kill their prey.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods)
The main ecosystem role played by spotted wobbegong is as a dominant predator, preying on the organisms listed above. They are a prey item for humans and for larger aquatic animals. Spotted wobbegong are also a host for a number of parasitic organisms. Thirty-three species of the onchobothriid tetraphylliean cestode (Cestoda) are parasitic to its spiral intestine (Eagle, 2005). Also, the nematode Echinocephalus overstreeti is a known parasite of the spotted wobbegong.
Commensal/Parasitic Species:
Although there is a limited amount of interest in the creation of a spotted wobbegong fishery, they are still commonly consumed by humans (Compagno, 2002). The meat is apparently excellent for eating and is mildly popular in Australia and surrounding areas. The tough skin makes very durable, decorative leather due to the unique patterning. Among the scuba diving industry, spotted wobbegongs are relatively easy and safe to observe by the average diver, thus contributing to the ecotourism of the area.
Positive Impacts: food ; body parts are source of valuable material; ecotourism
Spotted wobbegong are commonly caught by trawls and trammel nets, and inside lobster nets and pots (UN Atlas of the Oceans, 2005). They are considered pests in the lobster industry because they squeeze themselves inside lobster traps to eat both the bait and the catch. Spotted wobbegong are relatively docile sharks, and appear relatively sluggish when viewed by divers, but they should still be considered dangerous. They are not generally considered an aggressive species of shark, but have been known to bite people if provoked. In most cases, bites result when the shark is stepped on or if someone steps too close to their mouth and may be mistaken for prey (UN Atlas of the Oceans, 2005). Spotted wobbegong will assuredly become aggressive when speared or caught by nets. Their strong jaw musculature and impaling teeth, when combined with their tendency to hold on after biting, enables them to inflict serious damage. Several bites by wobbegong, both provoked and unprovoked, including bites on divers, have been reported. There have even been reported instances of a wobbegong biting fishing boats; some victims have lost limbs to the bite of a wobbegong. However, it is difficult to say which wobbegong species was responsible or the exact circumstances that led to these incidents.
Negative Impacts: injures humans (bites or stings)
Spotted wobbegong, like most other sharks, continue to grow throughout their lives and at a relatively slow pace (Eagle, 2005).
Development - Life Cycle: indeterminate growth
According to the IUCN Species Survival Commission, spotted wobbegong are considered near threatened, meaning the species has been evaluated but does not fit criteria for critically endangered, endangered, or vulnerable at the current time (Pollard et al, 2003). Spotted wobbegong are not currently listed on the United States Endangered Species Act list as either endangered or threatened. The Convention of International Trade in Endangered Species of Wild Fauna and Flora (CITES) also gives no special status to spotted wobbegongs.
Spotted wobbegong are commonly caught as bycatch and there appears to be low and stable catch levels in southern and western coastal fisheries (Pollard et al, 2003). However, serious declines have occurred in New South Wales which demonstrates the vulnerability of spotted wobbegongs to exploitation. Recreational fishing does not appear to be a dangerous threat to spotted wobbegongs, however spearfishers do catch a small number. The potential site attachment of spotted wobbegongs adds to their vulnerability to fishing pressure. This species has been targeted for their decorative skin pattern in the past, but are currently no longer being caught for their skin.
Spotted wobbegongs may be susceptible to damage to their inshore coastal habitats. Estuaries and seagrass beds may be home to important nursery areas for juvenile spotted wobbegongs (Pollard et al, 2003).
There is ongoing discussion regarding the management of spotted wobbegongs in the New South Wales area, but no management plan has yet been put in place (Pollard et al, 2003). Currently, there are no species-specific management plans in place in other Australian states. Some spotted wobbegong habitat areas may fall under the protected areas for Carcharias taurus (grey nurse sharks) in New South Wales. Spotted wobbegongs also occur in a few other marine protected areas in New South Wales, including Julian Rocks Aquatic Reserve, Solitary Islands Marine Park, Fly Point-Halifax Park Aquatic Reserve, and Jervis Bay Marine Park. Very recently, an in-possession limit of two spotted wobbegongs per person was instituted for recreational fishers (Pollard et al, 2003).
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: no special status
Any large fish or marine mammal is a potential predator of spotted wobbegong (Eagle, 2005). The most dangerous predator to spotted wobbegongs is humans, and if wobbegong meat continues to gain in popularity, the stability of the spotted wobbegong population may be in jeopardy. Their main anti-predatory adaptation is their cryptic coloration pattern, but in addition to their camouflage, spotted wobbegong can become dangerously aggressive if attacked, and have the ability to seriously injure, if not kill, the attacker.
Known Predators:
Anti-predator Adaptations: cryptic
Little is known about the natural breeding season of spotted wobbegong but, in captivity, breeding usually occurrs during July (Compagno, 2002). This may or may not be indicative of the natural breeding season and further research is necessary. During breeding season, the males are attracted to chemical pheromones released into the water by females. During copulation, the male will bite the female in the gill region, and use his modified pelvic fin, called a clasper, to insert sperm into the cloaca (Eagle, 2005). In captivity males fight fiercely over opportunities to court females, but it remains unclear if this male-male competition occurs among wild populations (UN Atlas of the Oceans, 2005). Unfortunately, little is known about the mating system of spotted wobbegong, but based on their behavior during breeding season, including the male-male competition, it would not be unexpected if they are a polygynous species.
Mating System: polygynous
Spotted wobbegong are ovoviviparous, meaning the eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or shortly after laying. Pups are unnourished while developing inside the mother and often eat unfertilized eggs as well as other pups. Litter sizes are usually large, with over twenty pups on average, the highest number of pups ever reported was 37 from a single female (Compagno, 2002). The young leave their mother almost immediately after birth, often to avoid being eaten by her. Little is known about the length of gestation for spotted wobbegong, but the maximum for the Orectolobidae family is 2 years. The average age at maturation for both male and female wobbegongs is unknown.
Breeding interval: Breeding intervals in spotted wobbegong are unknown.
Breeding season: Breeding occurs primarily in July in captivity.
Range number of offspring: 37 (high) .
Average number of offspring: 20.
Range gestation period: 24 (high) months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); ovoviviparous
All parental investment among spotted wobbegongs is made by the female, and all investment occurs while the young are still developing inside the mother. Newborn pups are immediately independent after birth and are capable of fending for themselves (Compagno, 1984).
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Female)
The spotted wobbegong (Orectolobus maculatus) is a carpet shark in the family Orectolobidae, endemic to Australia. It is a large, robust species, typically reaching 150–180 centimetres (59–71 in) in length. Coloured green, yellow, or brown, it has distinctive O-shaped spots throughout its body. It is nocturnal, resting at day and feeding on fish and invertebrates at night. An ovoviviparous species, the spotted wobbegong gives birth in the spring, during which time males can act aggressively towards other males and females. It has been known to bite humans, sometimes unprovoked, which can produce severe wounds. The species is fished for commercially in Australia, but it is not severely threatened. It is listed as a least-concern species on the IUCN Red List.
The species was described by Pierre Joseph Bonnaterre in 1778.[2] He classified it in the genus Squalus, with the full scientific name of Squalus maculatus. Bonnaterre redescribed the species in 1788 in Orectolobus, its current genus, making its full scientific name Orectolobus maculatus, with Squalus maculatus now a synonym of it.[3][4] Other synonyms of the species include Squalus barbatus (Gmelin, 1789), Squalus lobatus (Bloch & Schneider, 1801), Squalus appendiculatus (Shaw & Nodder, 1806), and Squalus labiatus (Bleeker, 1857). The spotted wobbegong's genus name is based on the Greek words "orektos" and "lobos", and translates roughly to "stretched out lobe".[3] Its specific name, maculatus, means "spotted" in Latin, named as such for the spotted pattern of its body. Alternate common names in English for the species include carpet shark, common carpet shark, common catshark, tassel shark, and wobbegong.[4]
The spotted wobbegong has previously been synonymised with Orectolobus parvimaculatus, the dwarf spotted wobbegong, in Western Australia. However, the spotted wobbegong has smaller and less dense dorsal fins, which lack the black markings that the dwarf spotted wobbegong's dorsal fins have, differentiating the two fishes. Therefore, the two wobbegongs are classified as two separate species. The spotted wobbegong has been confused with the Gulf wobbegong (Orectolobus hatei) in New South Wales, but the white marks of the spotted wobbegong, as well as its greater number of dermal lobes, distinguish the two species.[1] It is also frequently confused with the ornate wobbegong (Orectolobus ornatus).[5]
The following diagram shows the relationship between the spotted wobbegong and five other selected species in the genus Orectolobus:[6]
Genus OrectolobusO. maculatus
The spotted wobbegong has a large, robust body, which thins beyond its pelvic fins.[7] It grows in the range of 150–180 centimetres (59–71 in), but can reach 320 centimetres (130 in). It is green, yellow, or brown in colour,[4] with a darker back and darker saddles. It is covered with O-shaped spots, which distinguish it from other species that look similar to it. It has six to ten dermal lobes behind and in front of its eye[7] and a tubercle above its eye.[4] Its body lacks ridges or caudal keels.[3] Other characteristics of the species include dermal flaps surrounding the rim of its mouth,[8] large barbels extending from its nostrils,[7] and large spiracles.[3]
Like other sharks, the spotted wobbegong has abundant pores that operate as electroreceptors in its skin. They are used to detect the electric fields of nearby animals, making it easier to find prey. Marine & Freshwater Research, a peer-reviewed scientific journal, studied and compared the electroreceptors of the spotted wobbegong to those of the Australian angelshark (Squatina australis), a distantly related shark species. The spotted wobbegong has a more complex electrosensory system than the Australian angelshark, and the spotted wobbegong has a pore cluster inside its snout that is not present in the Australian angelshark. For both species, these electroreceptors are an important mechanism in feeding.[9]
A nocturnal species, the spotted wobbegong feeds at night and rests in sandy bottoms, coral reefs, and coastal bays in the day.[4] Adults most commonly occur on algae-covered rocky reefs and meadows of sea grass or sand, while juveniles are mostly found in estuaries.[5] Because of the species' colour pattern, it camouflages well on rocky bottoms. Although it has not been confirmed, the species may always return to a single site repeatedly throughout its life. Its diet consists of fishes, including luderick, scorpionfishes, sea basses, other smaller shark species (including individuals of their own species),[10] and rays, and various invertebrates, such as crabs, lobsters, and octopuses. Like all wobbegongs, it has a short mouth and broad pharynx, which allow it to suck up prey more easily. The species' prey have been known to wander right up to it, including near its mouth, sometimes nibbling its tentacles.[11]
The spotted wobbegong gathers in groups. The selection of specimens in a group was previously thought to be at random or due to food advantages, but a study led by Macquarie University concluded that spotted wobbegongs associate with preferred partners for "social" purposes, and some specimens do not associate at all.[12] The study occurred in a small marine reserve over a 15-month period. Out of the 15 tagged and observed specimens, 14 associated with more than one individual, and sex, size, or familiarity did not affect the association of groups.[13] Rob Harcourt, a researcher, stated "What we found was that sharks were interacting in a much more complex way than we predicted".[12]
Females give birth in the spring, after a gestation period of almost a year.[4] The species exhibits ovoviviparity, with embryos developing inside their mother's body until ready to hatch. Litters typically contain between 20–37 individuals.[5] Male wobbegongs in Sydney, likely including this species, fight with other males in the breeding season. Males have also been observed to bite females during courtship. Young are 21 centimetres (8.3 in) long directly after hatching and males become sexually mature when they reach roughly 60 centimetres (24 in).[11]
The spotted wobbegong is endemic to Australia, usually living in tropical waters no deeper than 218 metres (715 ft).[1] 38 specimens caught from 1882 to 1995 were found in waters 20–176 metres (66–577 ft) deep.[5] Sightings have been reported in Queensland, Victoria, South Australia, and Western Australia, in the western Pacific Ocean and eastern Indian Ocean. Records are also known of the species living in Tasmania and the Northern Territory, but these are likely to be invalid. Some records have misidentified other fish species living in Japan and the South China Sea as this species.[1][4]
The species' primary threat in eastern Australia is fishing for commercial purposes. Its flesh is edible and has thus caused it to be a target of fishing. In Queensland, it is sometimes caught as a bycatch but is not fished for intentionally. Its skin has been utilised for decorating historically, but whether it is utilised in such a way currently is unknown. Multiple conservation actions have taken place for this species, particularly since 2006. It is unknown if its population is decreasing or increasing, but it is not severely fragmented as of 2015. It is listed as a species of least concern on the red list of the International Union for Conservation of Nature as of 23 March 2015, after having been assessed as near threatened in 2003 and 2009.[1]
Although the spotted wobbegong is generally docile with humans, it is sometimes aggressive with them. Its defence mechanism is a bite, which can cause severe wounds due to the species' tendency to hold its bite for a long time.[3] Reports are known of it attacking people if they step on it or put a limb near its mouth.[3] Divers sometimes pull it by the tail during its daytime resting period, which often provokes it enough to bite.[14] The species can attack if caught with a fishing line or net, or if speared. In one circumstance, a spotted wobbegong specimen bit off a fisherman's foot.[11] It may also attack a human holding a speared or hooked fish, as well as the fish itself.[14] In 1789, Arthur Phillip, the first governor of New South Wales, wrote about the spotted wobbegong, which he called "Watts's Shark", in his book Voyage to Botany Bay. He said that it ferociously attacked the dog of "Mr. Watts":[2]
... after having lain on the deck for two hours seemingly quiet, on Mr Watts's dog passing by, the shark sprang on it with all the ferocity imaginable, and seized it by the leg, nor could the dog have disengaged himself had not the people near at hand come to his assistance
There have been reports of unprovoked attacks on humans, including divers well above the bottom,[15] while Compagno noted of such reports that "it is often difficult to determine which species was involved or what the precise circumstances were that led to the incident".[11] The International Shark Attack File lists 4 unprovoked attacks,[a] known to be by the spotted wobbegong, none of which were fatal.[17] In total, the Australian Shark Attack File has recorded 51 instances where the unprovoked attack,[b] on a human was confirmed to be by any species of wobbegong shark in the years 1900 to 2009, none of which were fatal.[18] Reports of wobbegongs biting boats are known in literature, but it has not been confirmed that these attacks were by the spotted wobbegong in particular.[11]
The spotted wobbegong was nominated for listing under the EPBC Act as a vulnerable species in 2013, but the nomination was rejected.[19] Threats to wobbegong include trawl fishing, beach seines, gillnets, lobster pots and traps, targeting by hook-and-line and spearfishing.[20]
Circa 2013, the IUCN Red List described the species as vulnerable in the waters of New South Wales and Near Threatened in Australian waters. Spotted wobbegongs are bycatch species in various fisheries and are allowed to be fished by recreational fishers in some Australian states,[19] as per the table below:
The spotted wobbegong (Orectolobus maculatus) is a carpet shark in the family Orectolobidae, endemic to Australia. It is a large, robust species, typically reaching 150–180 centimetres (59–71 in) in length. Coloured green, yellow, or brown, it has distinctive O-shaped spots throughout its body. It is nocturnal, resting at day and feeding on fish and invertebrates at night. An ovoviviparous species, the spotted wobbegong gives birth in the spring, during which time males can act aggressively towards other males and females. It has been known to bite humans, sometimes unprovoked, which can produce severe wounds. The species is fished for commercially in Australia, but it is not severely threatened. It is listed as a least-concern species on the IUCN Red List.
