Broadnose Sevengill Shark
   HOME

TheInfoList



OR:

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 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 c ...
s, while most
shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
have five gill slits, with the exception of the members of the order
Hexanchiformes The Hexanchiformes Help:IPA/English, /hɛkˈsæŋkɪfɔːrmiːz/ are a primitive Order (biology), order of sharks, numbering just five extant species in two Family (biology), families, Chlamydoselachidae and Cow shark, Hexanchidae. Chlamydoselach ...
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 Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...
, 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 Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...
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 Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
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 ''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a British reference book published annually, list ...
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 The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. The Jurassic constitutes the second and m ...
(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 California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
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 Bernard-Germain-Étienne de La Ville-sur-Illon, comte de Lacépède or La Cépède (; 26 December 17566 October 1825) was a French natural history, naturalist and an active freemason. He is known for his contribution to the Comte de Buffon's g ...
, 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. Notorynchus cepedianus head3.jpg, Front part including the seven gills Notorynchus cepedianus SI3.jpg, Bottom part Notorynchus cepedianus jaws.jpg, Jaws Notorynchus cepedianus upper teeth.jpg, Upper teeth Notorynchus cepedianus lower teeth.jpg, Lower teeth Broadnose sevengill shark braincase CT scan by John G. Maisey AMNH.jpg, CT scan of the broadnose sevengill shark's braincase


Range and habitat

The broadnose sevengill has so far been found in the western Pacific Ocean off
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
,
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
,
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
,
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
, the eastern Pacific Ocean off
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
, United States and
Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
, and the southern Atlantic Ocean off
Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
and
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
. It is significantly found in the
San Francisco Bay San Francisco Bay (Chochenyo language, Chochenyo: 'ommu) is a large tidal estuary in the United States, U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the cities of San Francisco, California, San ...
particularly near the
Golden Gate Bridge The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the strait connecting San Francisco Bay and the Pacific Ocean in California, United States. The structure links San Francisco—the northern tip of the San Francisco Peni ...
and
Alcatraz Island Alcatraz Island () is a small island about 1.25 miles offshore from San Francisco in San Francisco Bay, California, near the Golden Gate, Golden Gate Strait. The island was developed in the mid-19th century with facilities for a Alcatraz Isla ...
. Large, old individuals tend to live in deep offshore environments as far down as . 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 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 the Ancient Greek word (), meaning "the depths". ...
in nature, cruising along the sea floor and making an occasional foray to the surface. Individuals that live closer to the coast in South Africa tend to prefer more open areas with a sandy sea floor and sparse clumps of kelp.


Behavior

An opportunistic predator, the broadnose sevengill preys on a great variety of animals, and has been found at depths of , in offshore waters. It has been found to feed on other sharks (including the gummy shark, one of its main prey choices, and cowsharks), rays,
chimaeras Chimaeras are Chondrichthyes, cartilaginous fish in the order (biology), order Chimaeriformes (), known informally as ghost sharks, rat fish (not to be confused with rattails), spookfish, or rabbit fish; the last two names are also applied to B ...
,
cetaceans Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively c ...
,
pinnipeds Pinnipeds (pronounced ), commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant families Odobenidae (whose only living member is the walr ...
,
bony fishes Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes (cartila ...
and animal falls (seafloor
carrion Carrion (), also known as a carcass, is the decaying flesh of dead animals. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
). It will also feed on anything that fits in its mouth, such as shark egg cases,
sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...
s,
crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
s and any remains of rats, seabirds, and even deceased drowned humans. Research in 2003 found that its diet consisted of 30% mammals, with a frequency of occurrence of 35%. It is a frequent top predator in shallow waters, and has comb-like teeth, with the upper teeth having slender, smooth edged cusps to swallow small enough prey whole and lower teeth that are broad enough to bite flesh into pieces. These sharks occasionally hunt in packs to take larger prey, using tactics such as stealth to succeed. After feeding, it slowly digests for several days, and can go weeks until eating again. Larger, predatory sharks (such as the
great white shark The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocea ...
) can be a threat, and cannibalism among this species has also been recorded. The species has also been observed being preyed upon by
orcas The orca (''Orcinus orca''), or killer whale, is a toothed whale and the largest member of the oceanic dolphin family. The only extant species in the genus '' Orcinus'', it is recognizable by its black-and-white-patterned body. A cosmopoli ...
in
False Bay False Bay (Afrikaans: ''Valsbaai'') is a body of water in the Atlantic Ocean between the mountainous Cape Peninsula and the Hottentots Holland Mountains in the extreme south-west of South Africa. The mouth of the bay faces south and is demarc ...
, South Africa. When not actively hunting, it patrols the water, stealthily, while making very little movement except for moving its caudal fin; when prey is detected, they conserve their energy until ready to make an accelerated dash to attack. It can be one of the most abundant predators in coastal waters in summer; for example, in southeastern
Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...
, there is a high abundance of elasmobranchs (including the gummy shark) in coastal regions in summer. In New Zealand, it is also one of the most common inshore sharks. While it is mainly a nocturnal forager, it may opportunistically feed on prey casually found during the day; however, research in 2010 noted even amounts of activity during day and night. During this research, the shark was consistently detected at many depths, from bottom to near the surface, although it was mainly near the seafloor during the day. It also found that, as Norfolk Bay does not have adequate shelter cover, this species may use group formation to avoid predation. The sevengill, like all other members of
Hexanchiformes The Hexanchiformes Help:IPA/English, /hɛkˈsæŋkɪfɔːrmiːz/ are a primitive Order (biology), order of sharks, numbering just five extant species in two Family (biology), families, Chlamydoselachidae and Cow shark, Hexanchidae. Chlamydoselach ...
, is
ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...
. The broadnose sevengill lives for about 30 years, although the
Washington State Department of Fish and Wildlife The Washington Department of Fish and Wildlife (WDFW) is a department of the government of the state of Washington, United States of America. The WDFW manages over a million acres of land, the bulk of which is generally open to the public, an ...
lists a maximum of 49 years, with the males maturing at 4 to 5 years and the female 11 to 21 years; the average reproductive age for a female is 20 to 25 years. After a 12-month gestation period, the female moves to a shallow bay or estuary to give birth between April and May to a large litter of between 82 and 95 pups, measuring . In 2004 and 2005, along with research for the
sand tiger shark The sand tiger shark (''Carcharias taurus''), grey/gray nurse shark (in Australia), spotted ragged-tooth shark (in South Africa), or blue-nurse sand tiger, is a species of shark that inhabits subtropical and temperate waters worldwide. It inhabit ...
, there was research for the broadnose sevengill shark for development techniques for semen collection and artificial insemination to potentially increase breeding and lower overreliance on natural mating. Research in 2010 found that this shark has very poorly calcified
vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...
that cannot be used for age and growth estimations. Research in 2009 in Ría Deseado (RD) and Bahía San Julián (SJ), Argentina found that females were larger in RD than SJ and the heaviest female in RD was 70 kg while it was 36.9 kg in SJ. For the males, the heaviest in RD was 40 kg while it was 32.5 in SJ. Both locations also found the most significant to occur December and January. Research in 2014 also found that for the first time, reproductive hormones levels were found in the broadnose sevengill shark. for a few years before venturing out. The probable predators of this species are larger sharks. Research from 2002 showed that although juvenile sevengill sharks utilize nursery areas in a similar way, males mature faster than females even if they are the same size and thus males are more likely to leave the nursery area before females. In 2004, John G Maisey of the
American Museum of Natural History The American Museum of Natural History (AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. Located in Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 21 interconn ...
published a detailed analysis of the broadnose sevengill shark including imagery such as
CT scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...
s and
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...
of its braincase.


Interactions with humans

The
ISAF The International Security Assistance Force (ISAF) was a multinational military mission in Afghanistan from 2001 to 2014. It was established by United Nations Security Council Resolution 1386 according to the Bonn Agreement, which outlined t ...
considers this shark to be potentially dangerous because of its proximity to humans, and because of its aggressive behavior when provoked. It has also been noted as being aggressive towards divers and spearfishermen in both public aquariums and the wild. In 2013, in
Fiordland Fiordland (, "The Pit of Tattooing", and also translated as "the Shadowlands"), is a non-administrative geographical region of New Zealand in the south-western corner of the South Island, comprising the western third of Southland. Most of F ...
,
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
, a sevengill bit a diver's regulator and then her head. Human remains were also supposedly found in one specimen's stomach. Seven attacks on humans by the broadnose sevengill have been recorded since the 16th century, with no known fatalities . In 2020 a 13 year old girl was bitten while surfing at Oreti Beach in New Zealand. The girl continued to surf for an hour before realizing her leg was bleeding.


Conservation status

The broadnose sevengill is listed by the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...
as Vulnerable throughout its range. This species likely suffers great ongoing pressure from various types of fisheries, and from frequently being caught as
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 ...
. In
Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
, it's fished by rod and reel and broadnose sevengill shark fishing competitions have been occurring since the 1960s. It is also threatened by water pollution and is hunted for its liveroil and hide which is considered good quality in places such as China. In the early 1980s, intense fishing in the San Francisco Bay caused a local decline. In June 2018 the New Zealand Department of Conservation classified the broadnose sevengill shark 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 s ...
. Its meat and fins are in demand in countries such as the US,
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
,
Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...
,
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
,
Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
and
Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...
, and is packaged for frozen food. The broadnose sevengill is also a source of vitamin A and utilized by South African sport anglers for winter tournaments, however, this shark is not easy to land despite being readily hooked. It is frequently seen by tourists and in temperate water aquariums and can adapt to captivity. One of the aquariums that houses the broadnose sevengill shark,
Oregon Coast Aquarium The Oregon Coast Aquarium is an aquarium in Newport, Oregon, Newport in the U.S. state of Oregon. Opened in 1992, the facility sits on along Yaquina Bay near the Pacific Ocean. The aquarium was home to Keiko (orca), Keiko, the orca who starred ...
in
Newport, Oregon Newport is a city in Lincoln County, Oregon, Lincoln County, Oregon, United States. It was incorporated in 1882, though the name dates back to the establishment of a post office in 1868. Newport was named for Newport, Rhode Island. As of the 2010 ...
, has featured it as a "keynote species". There is also an app Sevengill Shark Tracking "Shark Observers" that allows divers to log sightings that are added to the Shark Observation Network, where the information supports "environmental awareness, assessment and policy making, and public participation at a global level". Not many conservation measures are known but it has been recorded from one marine reserve in South Africa and it occurs in
La Jolla Cove La Jolla Cove is a small cove with a beach that is surrounded by cliffs in La Jolla, a community of San Diego, California. Point La Jolla forms the south side of the cove. The area is protected as part of a marine reserve and is popular with sn ...
,
La Jolla La Jolla ( , ) is a hilly, seaside neighborhood in San Diego, California, occupying of curving coastline along the Pacific Ocean. The population reported in the 2010 census was 46,781. The climate is mild, with an average daily temperature o ...
,
San Diego San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in t ...
, California with the latter having an apparent population increase in 2013. 2009 research also suggested that Bahía Anegada be made a conservation area given the high number of sharks there. In Washington state, recreational fishing of broadnose sevengill shark is closed on all state waters. In
Victoria, Australia Victoria, commonly abbreviated as Vic, is a state in southeastern Australia. It is the second-smallest state (after Tasmania), with a land area of ; the second-most-populated state (after New South Wales), with a population of over 7 million; ...
, the
Department of Environment and Primary Industries The Department of Environment and Primary Industries (DEPI) was a state government department responsible for protecting the environment, boosting productivity in Victoria's food and fibre sector, management of natural resources and managing wate ...
sets a one bag limit and must be whole or in carcass form.


References


External links


Species Description of Notorynchus cepedianus at www.shark-references.com
*

{{Taxonbar, from=Q377591 broadnose sevengill shark Fish of the Pacific Ocean Marine fauna of East Asia Marine fish of Southern Africa Marine fish of Southern Australia Marine fish of New Zealand broadnose sevengill shark