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.
It is also known as sevengill shark or simply sevengill and was formerly known as cow shark and mud shark; it is called sevengill due to its seven gill slits. Because of this, it was listed along with the sharpnose sevengill shark (Heptranchias perlo) by Guinness World Records as having the most gill slits. It is similar to the sharpnose sevengill shark but the latter has a pointed snout and lacks spots on its dorsal surface. The sevengill species are also related to ancient sharks as fossils from the Jurassic Period (200 to 145 million years ago) also had seven gills. As recently as the 1930s and 1940s, the shark was targeted by fisheries along the coast of California and, once the commercial fishery receded, recreational fishing of the shark started in the 1980s and 1990s.
Taxonomy
Name
The genus name Notorynchus a portmanteau is derived from the Ancient Greek νῶτον (nôton, meaning "back") prefixed to the Ancient Greek ῥῠ́γχος (rhúnkhos, meaning “snout”). It has been interpreted that this refers to the spots on the broadnose sevengill's dorsal. The specific epithet cepedianus is derived from a variation of the name Lacepede, which refers to Bernard Germain de Lacépède, a French naturalist during the late 18th and early 19th century. Altogether, the scientific name as a whole literally means "Lacepede's back snout".
The common name "broadnose sevengill shark" refers to the seven gill slits the species possesses and the shape of its snout. Sometimes, the name is shortened to "sevengill shark" or simply "sevengill". However, a variety of other common names are known in many languages. Other known common names in English include the bluntnose sevengill shark, broad-snout, cowshark, ground shark, seven-gill cowshark, seven-gilled shark, spotted cow shark, spotted seven-gill shark, and Tasmanian tiger shark. Common names from other languages include cação-bruxa (Portuguese), cañabota gata, gatita, tiburón de 7 gallas, tiburón pinto, and tollo fume (Spanish), ebisuzame and minami-ebisuzame (Japanese), gevlekte zevenkieuwshaai (Dutch), Kammzähner and Siebenkiemiger Pazifischer Kammzähner (German), koeihaai (Afrikaans), k'wet'thenéchte (Salish), platneus-sewekiefhaai (Afrikaans), platnez and requin malais (French), siedmioszpar plamisty (Polish), and tuatini (Maori).
Description
The length at birth is while the mature male length is and mature female length is around . The maximum length found is . The maximum recorded weight is for a individual. The shark is large and active and has a large head but small eyes and snout. The mouth is broad and prominent. The shark has one dorsal fin at the back of the body that spans from the insertion to the tops of the pelvic fins. The mottled grey and white body is covered in a variable number of small black spots.