This week’s featured species an incredible ambush hunter that uses its tasselled body to lure in unsuspecting prey. The Tasselled Wobbegong (Eucrossorhinus dasypogon) is a medium sized shark, reaching lengths of up to 4.1 feet (1.25 m). Their bodies are dorso-ventrally flattened, much like the angle sharks, with wide heads and broad pectoral fins, with a body that tapers very abruptly into a narrow tail (Ebert, Fowler, & Dando, 2015). Their backs are covered with indistinct saddle-like markings and reticulated patterns of dark and light narrow bands that break up the form of their bodies along the reef, allowing them to better blend into their surroundings. Their heads are covered in numerous dermal lobes that branch off their chins, giving them a bearded or tasselled appearance, as well as their name sake (Compagno, 2001).
The tasselled wobbegong is a member of the family Orectolobidae, which contains 3 genera and 12 species of wobbegongs
- Genus Eucrossorhinus, which has only a single member, the tasselled wobbegong (Eucrossorhinus dasypogon)
- Genus Orectolobus, which has 10 members, including the ornate wobbegong (Orectolobus ornatus)
- Genus Sutorectus, which also has a single member, the cobbler wobbegong (Sutorectus tentaculatus)
The family Orectolobidae belongs to the order Orectolobiformes which contains 31 species in 7 different families including carpet sharks, wobbegongs, epaulette sharks, nurse sharks, blind sharks, and zebra sharks (Parker, 2008). This order also contains the family Rhincodontidae with a single species: Rhincodon typus, the whale shark (Parker, 2008)! So the tasselled wobbegong is related, though distantly, to the largest shark in the world! Pretty crazy, right?!
As an ambush predator, the tasselled wobbegong feeds by rapidly expanding its branchial, or gill, chamber as it opens its mouth. This creates negative pressure, drawing its prey directly into its mouth (Klimley, 2013). This style of ambush predation is common among dorso-ventrally compressed angel sharks in Squantiniformes, the wobbegongs of Orectolobidae, and the skates of Rajiformes (Klimley, 2013).
Discovery [Videographer]. (2015). The Tasselled Wobbegong Shark Lures in Prey for Ambush [Video Clip]. Retrieved from https://www.youtube.com/
Along with a quick, sudden attack, the wobbegong also has a set of jaws studded with narrow, sharp teeth that angle slightly backward into the mouth (Tricas, et al., 1997). These teeth are ideal for puncturing and drawing unsuspecting fish down into the wobbegong’s mouth. While the tasselled wobbegong primarily feeds on small reef fish and invertebrates found along the reef floor, they have been observed feeding on larger prey like other elasmobranchs from time to time!
Tasselled wobbegongs give birth to live young through a method of reproduction known as ovoviviparous. This means the pups develop inside the mom but do not have a direct connection to mom through an umbilical cord. Instead the young receive their nutrients from a yolk sac and are born when the pups are fully formed and the nutrients are depleted. Some shark species that are ovoviviparous are able to extract nutrients by means other than yolk sac during development; for example, sand tiger sharks (Carcharias taurus) are known to perform intrauterine cannibalism, and salmon shark (Lamna ditropis) pups consume other embryos in a process known as oophagy. However, it is thought that the tasselled wobbegongs have developed a subtype of ovoviviparity called lecithotrophic viviparous, in which the developing pup receives no additional nutrition from any other outside source other than its yolk sac. This hypothesis is based on observations of other orectolobid species, however, the tasselled wobbegong’s reproductive biology is not fully understood (Huveneers, Walker, Otway, & Harcourt, 2007; Huveneers, Otway, Harcourt, & Ellis, 2011).
Resorts World Sentosa [Videographer]. (2017). Tasselled Wobbegong pups at S.E.A. Aquarium piling on top of one another [Video Clip]. Retrieved from https://www.youtube.com/
There are no targeted fisheries for the tasselled wobbegong in their native Australia and they are unlikely to be taken as bycatch in trawler fisheries given their habitat preferences (Huveneers & Pillans, 2015). Unlike many other elasmobranch species, their fins have little or no value in the shark fin trade, so when they are accidentally caught, they are released alive whenever possible. Much of their habitat range is protected within the Great Barrier Reef Marine Park where fishing and trawling are illegal within the marine protected area. In regions surrounding New Guinea, local populations may be subjected to habitat destruction and loss through pollution and dynamite fishing. Monitoring within New Guinea is recommended to ensure that populations do not decline due to habitat exploitation. In Australia, members of Orectolobidae are occasionally sold in the local “fish and chips” trade. Individuals that are caught and sold in this market are typically larger species than the tasselled wobbegong, but some larger individuals may be harvested while smaller individuals are released alive. Historically, attractive skins have been used as decorative leather, though is it unknown if the practice still occurs (Last & Stevens, 2009). However, due to the lack of current threats to population decline, the International Union for the Conservation of Nature (IUCN) has categorized the tasselled wobbegong as a Least Concern species despite their population size and structure not being very well understood (Last & Stevens, 2009).
Authority: Bleeker, 1867
Family: Orectolobidae; 12 species
Length: 4.10 feet (1.25 m)
Weight: Maximum weight unknown
Habitat: Inshore coral reefs
Depth: Up to 164 feet (50 m)
Gestation: 10 – 11 months
Litter Range: Average of 20, up to 30 pups
Home Range: Southwest Pacific Ocean, native to Northern Australia and New Guinea
Diet: Small reef fish and invertebrates
IUCN Status: Least Concern
(Tricas, et al., 1997; Ebert, Fowler, & Dando, 2015; Huveneers & Pillans, 2015)
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Thanks so much for checking out the Tasselled Wobbegong! If you missed last week’s featured species, please be sure to check out the Sicklefin Weasel Shark! If there is a species of elasmobranch you’d love to know more about, leave me a comment or send me a message! I would love to do a feature on your favorite species. Also connect with me on Instagram and Facebook for even more elasmo fun!
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Featured Image Source
Hanson, J. (2006). Orectolobus dasypogon syn. Eucrossorhinus dasypogon [Digital Image]. Retrieved from https://commons.wikimedia.org/
Compagno, L. J. (2001). Sharks of the world. An annotated and illustrated catalogue of shark species known to date, vol 2. Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). FAO species catalogue for fishery purposes, 1, viii+-1.
Ebert, D. A., Fowler, S. L., & Dando, M. (2015). Sharks of the world: a fully illustrated guide. Wild Nature Press.
Huveneers, C. & Pillans, R.D. (2015). Eucrossorhinus dasypogon. The IUCN Red List of Threatened Species. Retrieved from https://www.iucnredlist.org/
Huveneers, C, Otway, N. M., Harcourt, R. G., & Ellis, M. (2011). Quantification of the maternal-embryonal nutritional relationship of elasmobranchs: case study of wobbegong sharks (genus Orectolobus). Journal of Fish Biology, 78, 1375–1389.
Huveneers, Charlie, Walker, T. I., Otway, N. M., & Harcourt, R. G. (2007). Reproductive synchrony of three sympatric species of wobbegong shark (genus Orectolobus) in New South Wales, Australia: reproductive parameter estimates necessary for population modelling. Marine and Freshwater Research, 58(8), 765.
Klimley, A. P. (2013). The biology of sharks and rays. University of Chicago Press.
Last, P., & Stevens, J. (2009). Sharks and Rays of Australia (2nd ed.). Collingwood: CSIRO Publishing.
Parker, S. (2008). The encyclopedia of sharks (2nd ed.). Buffalo, NY: Firefly Books Ltd.
Tricas, T. C., Deacon, K., Last, P., McCosker, J. E., Walker, T. I., & Taylor, L. (1997). The Nature Company Guides: Sharks and Rays. (L. Taylor, Ed.). Hong Kong: The Nature Company, Time Life Books.