The whitefin swellshark (''Cephaloscyllium albipinnum'') is a little-known

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

catshark Catsharks are ground sharks of the family Scyliorhinidae. They are the largest family of sharks with around 160 species placed in 17 genera. Although they are generally known as catsharks, some species can also be called dogfish due to previous ...

, belonging to the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Scyliorhinidae,

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to southeastern

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. It is found down, on the outer continental shelf and upper

continental slope A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin ...

. Reaching in length, this shark has a very thick body and a short, broad, flattened head with a large mouth. It is characterized by a dorsal color pattern of dark saddles and blotches over a brown to gray background, and light fin margins. When threatened the whitefin swellshark can inflate itself with water or air to increase its size. Reproduction is oviparous. As of 2019 The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

(IUCN) has assessed this species as Critically Endangered due to the significant decline of the population.

Taxonomy

Early specimens of the whitefin swellshark were often mistaken for the

Australian swellshark The Australian swellshark (''Cephaloscyllium laticeps'') or draughtboard shark, is a species of catshark, and part of the family Scyliorhinidae, endemic to southern Australia. This bottom-dwelling species can be found on the continental s ...

(''C. laticeps'') or the

draughtsboard shark The draughtsboard shark (''Cephaloscyllium isabellum'') is a species of catshark, and part of the family (biology), family Catshark, Scyliorhinidae, so named for its "checkerboard" color pattern of dark blotches. It is Endemism, endemic to New ...

(''C. isabellum''). In 1994, it was identified as a new species and known provisionally as ''Cephaloscyllium'' "sp. A", until it was formally described by Peter Last, Hiroyuki Motomura, and William White, in a 2008

Commonwealth Scientific and Industrial Research Organisation The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency responsible for scientific research. CSIRO works with leading organisations around the world. From its headquarters in Canberra, CSIRO ...

(CSIRO) publication. Its specific epithet ''albipinnum'' comes from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''albi'' meaning "white", and ''pinna'' meaning "fin", referring to its distinctive white fin margins. The

type specimen In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

is a long adult male caught near

Maria Island Maria Island or 'wukaluwikiwayna' in alawa kani) is a mountainous island located in the Tasman Sea">island.html" ;"title="alawa kani) is a mountainous island">alawa kani) is a mountainous island located in the Tasman Sea, off the east coast of ...

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

Description

The whitefin swellshark is a stocky species measuring up to long. The head is short, very wide, and greatly flattened, with a broadly rounded snout. The slit-like eyes are positioned high on the head, and are followed by tiny

spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...

s. The

nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

s are preceded by laterally expanded flaps of skin that do not reach the mouth. The mouth is large and strongly arched, without furrows at the corners. There are 90–116 upper tooth rows and 97–110 lower tooth rows; each tooth has three central cusps and often 1–2 additional small, lateral cusplets. The upper teeth are exposed when the mouth is closed. The fourth and fifth pairs of

gill slit Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of cartilaginous fish such as sharks and rays, as well as deep-branching vertebrates such as lampreys. In con ...

s lie over the

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

bases and are shorter than the first three. The pectoral fins are large and broad, with gently concave posterior margins. The first

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

is rounded and originates over the forward half of the pelvic fin bases. The second dorsal fin is much smaller and somewhat triangular, originating over the anal fin. The pelvic fins are small; males have very long

claspers In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's c ...

. The anal fin is larger than the second dorsal fin and is rounded in juveniles, becoming more angular in adults. The large

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

has a distinct lower lobe and a deep ventral notch near the tip of the upper lobe. The skin is thick and made rough by widely spaced, arrowhead-shaped dermal denticles with three horizontal ridges. The dorsal coloration is brown to gray with 9–10 dark saddles closely alternating with lateral blotches, including a large round blotch encompassing the gill slits; the fins are dark above with variably pale margins. The underside is lighter than the back, sometimes with darker or lighter blotches. Juveniles have more regular and better-defined blotches than adults.

Distribution and habitat

The whitefin swellshark is found off southeastern

from

Batemans Bay, New South Wales Bateman's is a 17th-century house located in Burwash, East Sussex, England. It was the home of Rudyard Kipling from 1902 until his death in 1936. The house was built in 1634. Kipling's widow Caroline bequeathed the house to the National Trust ...

to the

Great Australian Bight The Great Australian Bight is a large oceanic bight, or open bay, off the central and western portions of the southern coastline of mainland Australia. Extent Two definitions of the extent are in use – one used by the International Hydrog ...

as far as

Eucla, Western Australia Eucla is the easternmost locality in Western Australia, located in the Goldfields-Esperance region of Western Australia along the Eyre Highway, approximately west of the South Australian border. At the 2016 Australian census, Eucla had a popul ...

, including southern Tasmania from Maria Island to Point Hibbs. It is a bottom-dweller that inhabits the outer continental shelf and upper

, at a depth of .

Biology and ecology

Like other members of its genus, the whitefin swellshark can swallow water or air to dramatically increase its girth, as a defense against

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s. It is oviparous; the eggs are enclosed in smooth, light yellow flask-shaped capsules long and wide, with flanged edges and short horns at the corners that support long, coiled tendrils. The smallest known mature males and females measure and long respectively.Last, P.R., H. Motomura, and W. T. White (2008). "''Cephaloscyllium albipinnum'' sp. nov., a new swellshark (Carcharhiniformes: Scyliorhinidae) from southeastern Australia" in Last, P.R., W.T. White and J.J. Pogonoski (eds). ''Descriptions of new Australian Chondrichthyans''. CSIRO Marine and Atmospheric Research Paper No. 022: 147–157. (corrected) (invalid, listed in publication). Last, P.R. and J.D. Stevens (2009). ''Sharks and Rays of Australia'' (second ed). Harvard University Press. p. 209. .

Human interactions

The whitefin swellshark resides in a heavily fished region and while not a commercially targeted fish, are commonly captured as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

trawl Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different speci ...

s. The Australian South East Trawl Fishery, which operates off New South Wales, over a third of this shark's range reported that its catch rate dropped over 30% between 1967–77 and 1996–97. The South East Trawl Fishery Observer Program off southern Australia has also reported a slight population decline. As a result, the

(IUCN) has assessed the whitefin swellshark as critically endangered, and recommended close monitoring of bycatch levels. It is one of four species identified as threatened with extinction by trawling in a 2021 report.

References

{{Taxonbar, from=Q1950369

whitefin swellshark The whitefin swellshark (''Cephaloscyllium albipinnum'') is a little-known species of catshark, belonging to the family (biology), family Catshark, Scyliorhinidae, Endemism, endemic to southeastern Australia. It is found down, on the outer cont ...

Fauna of Victoria (Australia) Marine fish of Tasmania

Taxa named by Peter R. Last Taxa named by William Toby White Taxonomy articles created by Polbot