The prickly dogfish (''Oxynotus bruniensis'') is a poorly known species of

dogfish shark Squalidae, more commonly known as dogfish, dog sharks, or spiny dogfish, are one of several families of sharks categorized under Squaliformes, making it the second largest order of sharks, numbering 119 species across 7 families. Having earned t ...

in 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 ...

Oxynotidae ''Oxynotus'' is a genus of sharks in the order Squaliformes, commonly known as the rough sharks. It is the only extant genus in the family Oxynotidae. They live in deep waters in the Atlantic and western Pacific Oceans. Rough sharks are small ...

, inhabiting

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

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 ...

n and

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

waters. Reaching a length of , this brown to gray shark has a very thick body with a prominent "humpback" and extremely rough skin. It is further characterized by two enormous, sail-like

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 conv ...

s placed relatively close together. Both dorsal fins have a spine embedded mostly within the fleshy leading portion of the fin; the first dorsal spine is tilted forward. Found near the

sea floor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

over outer continental and insular shelves and upper slopes, the prickly dogfish is thought to be a slow-moving

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 ...

of small

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

s. It is

aplacental viviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

, with females giving birth to litters of around seven pups. This species is an uncommon

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 ...

of bottom trawls.

Taxonomy

Australian

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...

James Douglas Ogilby James Douglas Ogilby (16 February 1853 – 11 August 1925) was an Australian ichthyologist and herpetologist. Ogilby was born in Belfast, Ireland, and was the son of zoologist William Ogilby and his wife Adelaide, née Douglas. He received h ...

originally described the prickly dogfish from a desiccated specimen discovered on a beach on Bruny Island off southeastern

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

, Australia. He published his account in an 1893 issue of the scientific journal ''Records of the Australian Museum'' and, at the behest of

Tasmanian Museum The Tasmanian Museum and Art Gallery (TMAG) is a museum located in Hobart, Tasmania. The museum was established in 1846, by the Royal Society of Tasmania, the oldest Royal Society outside England. The TMAG receives 400,000 visitors annually. ...

Curator Alex Morton, named it ''Centrina bruniensis'' after the type locality. Subsequent authors have synonymized the genus ''Centrina'' with ''Oxynotus''.

Distribution and habitat

An uncommon resident of

waters, the prickly dogfish occurs off Australia from

Crowdy Head Crowdy Head is a headland on the coast of New South Wales, Australia, 7km from Harrington between Forster and Port Macquarie. The head is mostly cleared and was quarried between 1895 and 1901 for the Manning River training wall. Crowdy Head is ...

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

, around the southern coast of Tasmania, to as far as Esperance in

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. It also occurs off

and adjacent islands, and over the submarine Chatham Rise,

Challenger Plateau The Challenger Plateau is a large submarine plateau west of New Zealand and south of the Lord Howe Rise. It has an approximate diameter of and an area of about . The water depth over the plateau varies between to and is covered by up to of se ...

, and Campbell Plateau. This species is found close to the bottom over outer continental and insular shelves and upper slopes. It has been reported from a depth range of , but is typically found between down.

Description

With a very stout body and a highly arched back, the prickly dogfish has an unmistakable profile. Its head is slightly flattened, with a short rounded snout. The nostrils are large and closely spaced. The eyes are immediately followed by small round

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 mouth is relatively small and transverse, and almost surrounded by deep furrows coming from the mouth corners. The lips are thick and bear papillae (nipple-like structures). There are 12–19 upper and 11–13 lower tooth rows. The upper teeth are small with narrow upright cusps, while the lower teeth are large with broad knife-like triangular cusps. There are five 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. The body is roughly triangular in cross-section. The two dorsal fins are very tall with triangular, sail-like apexes; the anterior portion of each fin is fleshy, in which is embedded a spine with only the tip exposed. The first dorsal fin spine is tilted forward. The origin of the first dorsal fin lies over the gill slits, ahead of 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 ...

s. The second dorsal fin is smaller than the first, and the distance between it and the first dorsal fin is less than the length of its base. There are a pair of thick ridges running along the abdomen between the pectoral and

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s, which are smaller than the second dorsal fin. There is no

anal 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 se ...

. The

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 se ...

is broad and high, with a ventral notch near the tip of the upper lobe. The skin is extremely rough due to a covering of large

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...

s with narrow, knife-like crowns. The coloration is plain brown to gray, becoming translucent at the trailing margins of the pectoral and pelvic fins. This species grows to at least long, and may reach .

Biology and ecology

The unusual shape and sizable,

oily An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...

liver of the prickly dogfish suggests it is a slow swimmer that can hover over the sea floor with minimal effort. It probably hunts for small, bottom-dwelling

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s and fishes, perhaps facilitated by its large nostrils and

labial The term ''labial'' originates from '' Labium'' (Latin for "lip"), and is the adjective that describes anything of or related to lips, such as lip-like structures. Thus, it may refer to: * the lips ** In linguistics, a labial consonant ** In zoolog ...

papillae. This species is

; females have been recorded containing seven or eight mature eggs in their

ovaries The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...

, and one was gestating seven

embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...

s. Newborns measure about long. Males and females attain sexual maturity around and ≤ long, respectively. A known

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

of the prickly dogfish is the

monogenea Monogeneans are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they have both male and female reprod ...

n ''Asthenocotyle taranakiensis''.

Human interactions

The prickly dogfish is occasionally caught incidentally by bottom trawlers, and probably discarded. Some sources indicate the numbers caught have declined from historical levels, and 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 ...

assesses this species as

Near Threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...

. In June 2018 the New Zealand

Department of Conservation An environmental ministry is a national or subnational government agency politically responsible for the environment and/or natural resources. Various other names are commonly used to identify such agencies, such as Ministry of the Environment ...

classified the prickly dogfish as "Not Threatened" with the qualifiers "Data Poor" and "Secure Overseas" under the

New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had some ...

References

{{DEFAULTSORT:Prickly dogfish prickly dogfish Marine fish of Southern Australia Marine fish of New Zealand prickly dogfish