Prickly dogfish
Encyclopedia
The prickly dogfish is a poorly known species of dogfish shark
in the family
Oxynotidae, inhabiting temperate
Australia
n and New Zealand
waters. Reaching a length of 75 cm (29.5 in), 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
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 over outer continental and insular shelves
and upper slopes, the prickly dogfish is thought to be a slow-moving predator of small benthic organism
s. It is aplacental viviparous, with females giving birth to litters of around seven pups. This species is an uncommon bycatch
of bottom trawls, though there is presently insufficient information for the International Union for Conservation of Nature (IUCN) to assess its conservation status.
originally described the prickly dogfish from a desiccated specimen discovered on a beach
on Bruny Island off southeastern Tasmania
, 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
Curator
Alex Morton, named it Centrina bruniensis after the type locality
. Subsequent authors have synonymized
the genus Centrina with Oxynotus.
waters, the prickly dogfish occurs off Australia from Crowdy Head
in New South Wales
, around the southern coast of Tasmania, to as far as Esperance
in Western Australia
. It also occurs off New Zealand
and adjacent islands, and over the submarine Chatham Rise
, Challenger Plateau
, 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 45 to 1067 m (147.6 to 3,500.7 ft), but is typically found between 350 and 650 m (1,148.3 and 2,132.5 ft) down.
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
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 fins. 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 fins, which are smaller than the second dorsal fin. There is no anal fin. The caudal fin 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 denticles 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 75 cm (29.5 in) long, and may reach 91 cm (35.8 in).
of the prickly dogfish suggests that it is a slow swimmer that can hover over the sea floor with minimal effort. It probably hunts for small, bottom-dwelling invertebrate
s and fish
es, perhaps facilitated by its large nostrils and labial
papillae. This species is aplacental viviparous; females have been recorded containing 7–8 mature eggs in their ovaries
, and one was gestating
7 embryo
s. Newborns measure approximately 24 cm (9.4 in) long. Males and females attain sexual maturity
at approximately 55–60 cm (21.7–23.6 in) and ≤67 cm (26.4 in) long respectively. A known parasite of the prickly dogfish is the monogenea
n Asthenocotyle taranakiensis.
by bottom trawlers, and probably discarded. There is some indication that the numbers bycaught have declined from historical levels, but at present the International Union for Conservation of Nature (IUCN) lacks sufficient data to assess this species beyond Data Deficient
.
Squaliformes
Squaliformes is an order of sharks that includes about 97 species in seven families.Members of the order have two dorsal fins, which usually possess spines, no anal fin or nictitating membrane, and five gill slits. In most other respects, however, they are quite variable in form and size...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Oxynotidae, inhabiting temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
waters. Reaching a length of 75 cm (29.5 in), 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
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
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 over outer continental and insular shelves
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
and upper slopes, the prickly dogfish is thought to be a slow-moving predator of small benthic organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
s. It is aplacental viviparous, with females giving birth to litters of around seven pups. This species is an uncommon bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
of bottom trawls, though there is presently insufficient information for the International Union for Conservation of Nature (IUCN) to assess its conservation status.
Taxonomy
Australian ichthyologist James Douglas OgilbyJames Douglas Ogilby
James Douglas Ogilby was an Australian ichthyologist.Ogilby was born in Belfast, Ireland, and was the son of zoologist William Ogilby. He received his education at Winchester College, England, and Trinity College, Dublin.Ogilby worked for the British Museum before joining the Australian Museum in...
originally described the prickly dogfish from a desiccated specimen discovered on a beach
Beach
A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...
on Bruny Island off southeastern Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
, Australia. He published his account in an 1893 issue of the scientific journal
Scientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. There are thousands of scientific journals in publication, and many more have been published at various points in the past...
Records of the Australian Museum and, at the behest of Tasmanian Museum
Tasmanian Museum and Art Gallery
The Tasmanian Museum and Art Gallery is a museum located in Hobart, Tasmania. The museum was established in 1843, by the Royal Society of Tasmania under the leadership of Sir John Franklin, the oldest Royal Society outside of England.-Governance:...
Curator
Curator
A curator is a manager or overseer. Traditionally, a curator or keeper of a cultural heritage institution is a content specialist responsible for an institution's collections and involved with the interpretation of heritage material...
Alex Morton, named it Centrina bruniensis after the type locality
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
. Subsequent authors have synonymized
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
the genus Centrina with Oxynotus.
Distribution and habitat
An uncommon resident of temperateTemperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
waters, the prickly dogfish occurs off Australia from Crowdy Head
Crowdy Head
Crowdy Head is a headland on the coast of New South Wales, Australia, between Forster and Port Macquarie, overlooking the mouth of the Manning River. It is the site of Crowdy Head Light, a tall lighthouse built in 1878.-References:...
in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, around the southern coast of Tasmania, to as far as Esperance
Esperance, Western Australia
Esperance is a large town in the Goldfields-Esperance region of Western Australia, located on the Southern Ocean coastline approximately east-southeast of the state capital, Perth. The shire of Esperance is home to 9,536 people as of the 2006 census, its major industries are tourism, agriculture,...
in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. It also occurs off New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
and adjacent islands, and over the submarine Chatham Rise
Chatham Rise
The Chatham Rise is an area of ocean floor to the east of New Zealand, forming part of the Zealandia continent. It stretches for some from near the South Island in the west, to the Chatham Islands in the east...
, Challenger Plateau
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 . The plateau originated in the Gondwanan breakup and is one of the five major submerged parts of Zealandia, a largely submerged continent....
, and Campbell Plateau
Campbell Plateau
The Campbell Plateau is a large submarine plateau to the south of New Zealand and the Chatham Rise. It originated in the Gondwanan breakup and is part of Zealandia, a largely submerged continent. The Bounty Islands, Antipodes Islands, Auckland Islands and Campbell Island are on the...
. This species is found close to the bottom over outer continental and insular shelves
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
and upper slopes. It has been reported from a depth range of 45 to 1067 m (147.6 to 3,500.7 ft), but is typically found between 350 and 650 m (1,148.3 and 2,132.5 ft) 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 spiracleSpiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
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 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, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
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 fins. 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 fins, which are smaller than the second dorsal fin. There is no anal fin. The caudal fin 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 denticles 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 75 cm (29.5 in) long, and may reach 91 cm (35.8 in).
Biology and ecology
The unusual shape and sizable, oily liverLiver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
of the prickly dogfish suggests that it is a slow swimmer that can hover over the sea floor with minimal effort. It probably hunts for small, bottom-dwelling invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s and fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
es, perhaps facilitated by its large nostrils and labial
Lip
Lips are a visible body part at the mouth of humans and many animals. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech...
papillae. This species is aplacental viviparous; females have been recorded containing 7–8 mature eggs in their ovaries
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
, and one was gestating
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
7 embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s. Newborns measure approximately 24 cm (9.4 in) long. Males and females attain sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at approximately 55–60 cm (21.7–23.6 in) and ≤67 cm (26.4 in) long respectively. A known parasite of the prickly dogfish is the monogenea
Monogenea
Monogenea are a group of largely ectoparasitic members of the flatworm phylum Platyhelminthes, class Monogenea.-Characteristics:Monogenea are very small parasitic flatworms mainly found on skin or gills of fish....
n Asthenocotyle taranakiensis.
Human interactions
The prickly dogfish is occasionally caught incidentallyBycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
by bottom trawlers, and probably discarded. There is some indication that the numbers bycaught have declined from historical levels, but at present the International Union for Conservation of Nature (IUCN) lacks sufficient data to assess this species beyond Data Deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
.