Orectolobus maculatus

Geographic Range

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 pacific ocean
  • native native

Habitat

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).

• Habitat Regions
• temperate temperate
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• benthic benthic
• reef reef
• coastal coastal

• Other Habitat Features
• estuarine estuarine
• intertidal or littoral intertidal or littoral
• caves

Physical Description

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).

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

Development

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 indeterminate growth

Reproduction

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 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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• ovoviviparous 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

Lifespan/Longevity

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.

Behavior

Spotted wobbegongs are rather sluggish when compared to other species of sharks. They are often found completely motionless on the sea floor and remain inactive for extended periods of time (Compagno, 2002). They are a nocturnal species and spend most of the day resting. Their cryptic coloration pattern allows them to remain relatively unnoticed. Preliminary observations indicate site specificity among some spotted wobbegongs, with some individuals returning to the same site alone, as well as some groups of around a dozen individuals returning together. In general, spotted wobbegong appear to be a solitary species, but at times do congregate in groups.

Spotted wobbegong feed primarily at night, and may swim along the bottom in a manner similar to nurse sharks ( Ginglymostomatidae ) (Compagno, 2002). It remains unclear if spotted wobbegong are active, prowling hunters or ambush predators that sit and wait for unsuspecting prey to get too close. Some wobbegongs have been observed sneaking up to bait items as if stalking, but this may not be the primary mode of hunting for live prey.

• Key Behaviors
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

Spotted wobbegong do not appear to have a specific home range, however as mentioned above, some site attachment has been observed (Compagno, 2002). More research is necessary to explore this question further.

Communication and Perception

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 chemical

• Perception Channels
• visual visual
• chemical chemical
• electric electric

Food Habits

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.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods

• Animal Foods
• fish
• mollusks
• aquatic crustaceans

Predation

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.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

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.

Economic Importance for Humans: Positive

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 food
• body parts are source of valuable material
• ecotourism ecotourism

Economic Importance for Humans: Negative

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

Conservation Status

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).

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (), Animal Diversity Web.

Todd Szcodronski (author), University of Michigan-Ann Arbor, Kevin Wehrly (editor, instructor), University of Michigan-Ann Arbor.

References

Campbell, D. 2005. "MarineBio" (On-line). Accessed October 17, 2005 at http://marinebio.org/species.asp?id=384 .

Carrier, J. 2005. Shark. Microsoft Encarta Online Encyclopedia . Microsoft Corporation. Accessed December 07, 2005 at http://encarta.msn.com/encyclopedia_761552860_2/Shark.html#howtocite .

Compagno, L. 1984. Sharks of the World. An annotated and illustrated catalogue of shark species known to date. part 1- Hexanchiformes to Lamniformes. FAO Species catalogue , 4/1: 1-249. Accessed October 13, 2005 at http://www.fishbase.org/Summary/SpeciesSummary.php?id=758 .

Compagno, L. 2002. Sharks Of The World: An Annotated and Illustrated CAtalogue of Shark Species Known To Date. FAO Species CAtalogue for Fishery Purposes , No. 1, Vol. 2: 155-157. Accessed October 6th, 2005 at ftp://ftp.fao.org/FI/document/sidp/x9293E_SharksVol2/X9293E00.pdf .

Eagle, D. 2005. "Icthyology at the Florida Museum of Natural History" (On-line). Accessed October 6th, 2005 at http://www.flmnh.ufl.edu/fish/Gallery/Descript/SpotWobbegong/SpotWobbegong.html .

Myers, P., R. Espinosa, S. Parr, T. Jones, G. Hammond, T. Dewey. 2005. "Animal Diversity Web" (On-line). Accessed October, 6th, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/classification/Orectolobiformes.html#Orectolobiformes .

Pollard, D., I. Gordon, A. Flaherty, J. Pogonski. 2003. "IUCN Red List of Threatened Species" (On-line). Accessed October 6th, 2005 at http://www.redlist.org/search/details.php?species=41837 .

Wu, E. 1994. Kinematic Analysis of Jaw Protusion In Orecolobiform Sharks - A New Mechanism For Jaw Protrusion In Elasmobranchs. Journal Of Morphology , 222/2: 175-190.

2005. "UN Atlas of the Oceans" (On-line). Accessed October 6th, 2005 at http://www.oceansatlas.org/unatlas_gifs/offsiteframe.jsp?url=http%3A%2F%2Fwww.fao.org%2Ffigis%2Fservlet%2FFiRefServlet%3Fds%3Dspecies%26fid%3D13943&ctn=3441&kot=web-sites .