Spurdogs | |
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Spiny dogfish (Squalus acanthias) | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Subdivision: | Selachimorpha |
Order: | Squaliformes |
Family: | Squalidae |
Genus: | Squalus Linnaeus, 1758 |
Type species | |
Squalus acanthias Linnaeus, 1758 | |
Synonyms | |
Squalus is a genus of dogfish sharks in the family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower jaws similar in size, caudal peduncle with lateral keels; upper precaudal pit usually present, and caudal fin without subterminal notch. In spurdogs, the hyomandibula (the bone connecting the braincase to the jaws) is oriented at a right angle to the neurocranium, while in other sharks, the hyomandibula runs more parallel to the body. This led some to think that the upper jaw of Squalus would not be as protractile as the jaws of other sharks. However, a study that compared different jaw suspension types in sharks showed that this is not the case and that Squalus is quite capable of protruding its upper jaw during feeding. [5]
The name comes from squalus, the Latin for shark; this word is the root for numerous words related to sharks such as squaline and scientific names for sharks, such as the order Squaliformes.
Currently, 33 recognized species are placed in this genus:
The Squaliformes are an order of sharks that includes about 126 species in seven families.
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 their name after a group of fishermen reportedly observed the species chasing down smaller fish in dog-like packs, dogfish have slender, streamlined bodies, usually more compact in comparison to other species, and a pointed snout. Dogfish likewise have two dorsal fins, each with smooth spines, but no anal fin, and their skin is generally rough to the touch. As the species reaches adulthood, males usually measure a maximum of 100 cm, while females typically measure 125 cm long. The species therefore exhibits female-dominant sexual dimorphism.
The spiny dogfish, spurdog, mud shark, or piked dogfish is one of the best known species of the Squalidae (dogfish) family of sharks, which is part of the Squaliformes order.
The mandarin dogfish is a dogfish, a member of the family Squalidae in the order Squaliformes. It is found at depths of 140–650 metres (460–2,130 ft) off southern Japan, Taiwan, and Indonesia. Populations off Australia and New Zealand were formerly included in this species, but in 2007 these were assigned to a new species, the southern mandarin dogfish. It is not clear which of these species is involved in other populations from the tropical West Pacific.
Cirrhigaleus is a genus of sharks in the Squalidae (dogfish) family, which is part of the Squaliformes order.
The blacktailed spurdog is a dogfish, a member of the family Squalidae, found around New Caledonia in the central Pacific Ocean, at depths from 320 to 320 m. Its length is up to 75 cm.
The shortspine spurdog is a dogfish, a member of the family Squalidae, found on continental shelves off Japan in temperate waters, from the surface to 950 m. Its length is up to 75 cm.
Squalus altipinnis, the western highfin spurdog, is a dogfish of the family Squalidae found on the continental shelf off Western Australia, at depths between 220 and 510 m. Its reproduction is ovoviviparous.
Squalus crassispinus, the fatspine spurdog, is a dogfish of the family Squalidae, found on the continental shelf off the northern coast of Western Australia, at depths of 180 to 200 metres. The length of the longest male specimen measured is 56 centimetres (22 in).
Squalus nasutus, the western longnose spurdog, is a dogfish of the family Squalidae, found on the continental shelf off the northwest and southwest coasts of Western Australia, at depths between 300 and 510 m. Its length is at least 55 cm.
The Taiwan spurdog is a species of shark in the genus Squalus. It was accidentally found in Taiwan's Tashi fish market by William Toby White and a colleague of the CSIRO in Hobart, Australia. They named it S. formosus. It has also been recorded from the coast of Japan, near Kyushu and Shikoku.
The bighead spurdog is a rare and little-known species of dogfish shark in the family Squalidae. It is found in deep water south of New Caledonia, and over the Norfolk Ridge. Reaching at least 90 cm (35 in) in length, this stocky shark is brown above and light below, with a broad head and two dorsal fins with long spines. It is the only member of its genus with both one- and three-pointed dermal denticles. An infrequent bycatch of longline fisheries, this species is listed under Data Deficient by the International Union for Conservation of Nature (IUCN).
Squalus montalbani, the Philippine spurdog or Indonesian greeneye spurdog, is a relatively large species of dogfish shark native to waters off the coast of Australia, the Philippines, and Indonesia. The species was identified in 1912 from a specimen caught off the coast of Luzon Island, and has been both bycatch and a targeted species in fisheries since. Its taxonomy is complex, having been renamed in 1931, being misidentified as a type of shortspine spurdog, then being revived as a species in 2007.
The Pacific spiny dogfish is a common species of the Squalidae (dogfish) family of sharks and are among the most abundant species of sharks in the world. This species is closely related to Squalus acanthias and for many years they were treated as a single species. Recent research, using meristic, morphological and molecular data led to the resurrection of the Pacific spiny dogfish as a separate species. The American Fisheries Society recommends the common name "Pacific spiny dogfish" for Squalus suckleyi over alternatives such as "spotted spiny dogfish" and "North Pacific spiny dogfish" and "spiny dogfish" for Squalus acanthias.
The greeneye spurdog is a species of dogfish described in 2007. It is a member of the family Squalidae, found off the coast of southeastern Australia. The length of the longest specimen measured is 85.6 cm (33.7 in). It was considered conspecific with the shortspine spurdog.
Edmund's spurdog is a dogfish described in 2007. It is a member of the family Squalidae, found off western Australia and Indonesia. The length of the longest specimen measured is 70.0 cm (27.6 in).
The Indonesian shortsnout spurdog is a dogfish described in 2007. It is a member of the family Squalidae, found off Indonesia. The length of the longest specimen measured is 52.2 cm (20.6 in).