Broadnose sevengill shark

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Broadnose sevengill shark
Notorynchus cepedianus 2.jpg
Conservation status
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Chondrichthyes
Subclass:Elasmobranchii
Superorder:Selachimorpha
Order:Hexanchiformes
Family:Hexanchidae
Genus:Notorynchus
Ayres, 1855
Species:N. cepedianus
Binomial name
Notorynchus cepedianus
(Péron, 1807)
Notorynchus cepedianus distmap.png
Range of the broadnose sevengill shark
Synonyms

Heptranchias haswelli* Ogilby, 1897
Heptranchias pectorosus Garman, 1884
Heptranchias spilotus Lahille, 1913
Notidanus ferox Perez Canto, 1886
Notidanus indicus Agassiz, 1838
Notidanus medinae Philippi, 1902
Notidanus wolniczkyi Philippi, 1902
Notorynchus macdonaldi Whitley, 1931
Notorynchus maculatus Ayres, 1855
Notorhynchus borealis Gill, 1864
Notorhynchus ocellatus Devincenzi, 1920
Squalus cepedianus Péron, 1807
Squalus platycephalus Tenore, 1809


* ambiguous synonym

 
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Broadnose sevengill shark
Notorynchus cepedianus 2.jpg
Conservation status
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Chondrichthyes
Subclass:Elasmobranchii
Superorder:Selachimorpha
Order:Hexanchiformes
Family:Hexanchidae
Genus:Notorynchus
Ayres, 1855
Species:N. cepedianus
Binomial name
Notorynchus cepedianus
(Péron, 1807)
Notorynchus cepedianus distmap.png
Range of the broadnose sevengill shark
Synonyms

Heptranchias haswelli* Ogilby, 1897
Heptranchias pectorosus Garman, 1884
Heptranchias spilotus Lahille, 1913
Notidanus ferox Perez Canto, 1886
Notidanus indicus Agassiz, 1838
Notidanus medinae Philippi, 1902
Notidanus wolniczkyi Philippi, 1902
Notorynchus macdonaldi Whitley, 1931
Notorynchus maculatus Ayres, 1855
Notorhynchus borealis Gill, 1864
Notorhynchus ocellatus Devincenzi, 1920
Squalus cepedianus Péron, 1807
Squalus platycephalus Tenore, 1809


* ambiguous synonym

The broadnose sevengill shark (Notorynchus cepedianus) is the only extant member of the genus Notorynchus, in the family Hexanchidae. It is recognizable because of its seven gill slits, while most shark species have five gill slits, with the exception of the members of the order Hexanchiformes and the sixgill sawshark. This shark has a large, thick body, with a broad head and blunt snout. The top jaw has jagged, cusped teeth and the bottom jaw has comb-shaped teeth. Its single dorsal fin is set far back along the spine towards the caudal fin, and is behind the pelvic fins. In this shark the upper caudal fin is much longer than the lower, and is slightly notched near the tip. Like many sharks, this sevengill is counter-shaded. Its dorsal surface is silver-gray to brown in order to blend with the dark water and substrate when viewed from above. In counter to this, its ventral surface is very pale, blending with the sunlit water when viewed from below. The body and fins are covered in a scattering of small black & white spots. In juveniles, their fins often have white margins.

Measurements[edit]

Length at birth: 40–45 cm. Mature Male Length: 1.3-1.7 m. Mature Female Length: Around 2 m. Max. Length Found: 2.9 m.

Range and habitat[edit]

The broadnose sevengill has so far been found in the western Pacific Ocean off China, Japan, Australia, New Zealand, the eastern Pacific Ocean, and the southern Atlantic Ocean off Argentina and South Africa. Large, old individuals tend to live in deep offshore environments as far down as 136 m. However, most individuals live in either the deep channels of bays, or in the shallower waters of continental shelves and estuaries. These sharks are mainly benthic in nature, cruising along the sea floor and making an occasional foray to the surface.[1]

Behavior[edit]

An opportunistic predator, the broadnose sevengill preys on a great variety of animals. It has been found to feed on sharks, rays, chimaeras, cetaceans, pinnipeds, bony fishes, and carrion. These sharks occasionally hunt in packs to take down larger prey, using tactics such as stealth to succeed. This sevengill, like all other members of Hexanchiformes, is ovoviviparous. After a 12-month gestation period, the female moves to a shallow bay or estuary to give birth to a large litter of up to 82 pups. The juveniles remain in this nursery for a few years before venturing out. The probable predators of this species are larger sharks.

Conservation[edit]

The broadnose sevengill is listed by the IUCN Red List as Data Deficient throughout most of its range, and as possibly Vulnerable in the northeast Pacific. This species likely suffers great pressure from various types of fisheries, and from frequently being caught as bycatch. The International Shark Attack File considers this shark to be potentially dangerous because of its proximity to humans, and because of its aggressive behavior when provoked. Six attacks on humans by the broadnose sevengill, the latest being in 2013 in New Zealand, have been recorded since the 16th century, with no known fatalities. [2][3]

References[edit]

  1. ^ Compagno, Leonardo, Dando, Marc and Fowler, Sarah. Sharks of the World. Princeton University Press. 2005. p. 67-68
  2. ^ Shark Attacks Diver in Fiordland - national | Stuff.co.nz
  3. ^ [1] accessed 13 July 2010

External links[edit]