The bluntnose sixgill shark (''Hexanchus griseus''), often simply called the cow shark, is the largest
hexanchoid shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
, growing to in length.
It is found in tropical and temperate waters worldwide and its diet is widely varied by region.
The bluntnose sixgill is a species of sixgill sharks, of genus ''Hexanchus'', a genus that also consists of two other species: the bigeye sixgill shark (
''Hexanchus nakamurai'') and the Atlantic sixgill shark (
''Hexanchus vitulus''). Through their base pairs of mitochondrial genes COI and ND2, these three species of sixgills widely differ from one another.
Taxonomy
![FMIB 46035 Six-Gilled Shark](https://upload.wikimedia.org/wikipedia/commons/5/5d/FMIB_46035_Six-Gilled_Shark.jpeg)
The first scientific description of the bluntnose sixgill shark was authored in 1788 by
Pierre Joseph Bonnaterre
Abbé Pierre Joseph Bonnaterre (1752, Aveyron – 20 September 1804, Saint-Geniez-d'Olt) was a French zoology, zoologist who contributed sections on cetaceans, mammals, birds, reptiles, amphibians, fish, and insects to the ''Tableau encyclopéd ...
. As a member of the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Hexanchidae, it has more close relatives in the fossil record than living relatives. The related living species include the
dogfish, the
Greenland shark
The Greenland shark (''Somniosus microcephalus''), also known as the gurry shark, grey shark, or by the Kalaallisut name ''eqalussuaq'', is a large shark of the family Somniosidae ("sleeper sharks"), closely related to the Pacific and souther ...
, and other six- and seven-gilled sharks. Some of the shark's relatives date back 200 million years. This shark is a notable species due to both its primitive and current physical characteristics.
Description
![Hexanchus griseus seattle](https://upload.wikimedia.org/wikipedia/commons/5/55/Hexanchus_griseus_seattle.jpg)
The bluntnose sixgill shark has a large body and long tail. The snout is blunt and wide, and its eyes are small. There are 6 rows of saw-like teeth on its lower jaw and smaller teeth on its upper jaw.
Skin color ranges from tan, through brown, to black. It has a light-colored
lateral line
The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...
down the sides and on the fins' edges, and darker colored spots on the sides. They also get stains/spots on their neural arches, and the number of stains increase as they get older. Its pupils are black and its eye color is a
fluorescent
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...
blue-green. The bluntnose sixgill shark can grow to ,
. A work from the 1880s stated that a bluntnose sixgill shark caught off Portugal in 1846 measured 8 m (26.5 ft). This specimen was originally reported in an 1846 work and said to be only 0.68 m (2.3 ft) long. Adult males generally average between , while adult females average between . The average weight of an adult bluntnose sixgill shark is 500 kilograms (1102 lbs). Large specimens may reach in length and in weight.
The bluntnose sixgill shark resembles many of the fossil sharks from the
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
period. A greater number of ''Hexanchus'' relatives occur in the fossil record than are alive today. They have one
dorsal fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...
located near the
caudal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
. The
pectoral fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...
s are broad, with rounded edges. The six gill slits give the shark its name. Most common sharks today only have five gill slits.
Hexanchus griseus jaws male.jpg, Jaws, male
Hexanchus griseus upper teeth male.jpg, Upper teeth, male
Hexanchus griseus upper teeth female.jpg, Upper teeth, female
Hexanchus griseus lower teeth male.jpg, Lower teeth, male
Hexanchus griseus lower teeth female.jpg, Lower teeth, female
Growth and development
In general, the size (in length and weight) of the sixgills increase with maturity. With the male sharks specifically, their sexual maturity is usually determined by the length of their
clasper
In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating.
Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's c ...
s. While juveniles have short and flexible ones, mature male sixgills have rigid, calcified longer ones. On the other hand, the length-weight relationship of females tend to increase very rapidly as they get to the onset of their
sexual maturity
Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definitio ...
.
Distribution and habitat
![Hexanchus griseus santa rosa](https://upload.wikimedia.org/wikipedia/commons/7/7d/Hexanchus_griseus_santa_rosa.jpg)
With a global distribution in tropical and temperate waters, the bluntnose sixgill shark is found in a latitudinal range between
65°N and
48°S in the
Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...
,
Indian
Indian or Indians may refer to:
Peoples South Asia
* Indian people, people of Indian nationality, or people who have an Indian ancestor
** Non-resident Indian, a citizen of India who has temporarily emigrated to another country
* South Asia ...
, and
Pacific
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
oceans. It has been seen off the coasts of
North
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography.
Etymology
T ...
and
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
from
North Carolina
North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
to
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
and
Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...
to
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
. In the eastern Atlantic, it has been caught from
Iceland
Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...
to
Namibia
Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...
, in the Indo-Pacific it has been caught from
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
north to
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
and east to Hawaii
and in the
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...
it has been caught in
Greece
Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders with ...
and
Malta
Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...
. Fossilized remains of this species from the
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
epoch have also been discovered in
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
. It typically swims near the ocean floor or in the
water column
A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...
over the
continental shelf
A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...
in poorly lit waters.
[ It is usually found from the surface, inhabiting the ]outer continental shelf
The Outer Continental Shelf (OCS) is a feature of the geography of the United States. The OCS is the part of the internationally recognized continental shelf of the United States which does not fall under the jurisdictions of the individual U. ...
, but its depth range can extend from . Juveniles will swim near the shoreline in search of food, sometimes in water as shallow as , but adults typically stay at depths greater than . It can be seen near the ocean's surface only at night.[
An adult bluntnose sixgill shark was recently seen at a depth of in the ]Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
. On December 2, 2017, the ROV camera of Paul Allen
Paul Gardner Allen (January 21, 1953 – October 15, 2018) was an American business magnate, computer programmer, researcher, investor, and philanthropist. He co-founded Microsoft Corporation with childhood friend Bill Gates in 1975, which h ...
's research vessel RV Petrel
RV ''Petrel'', or R/V ''Petrel'' (IMO: 9268629, MMSI: 235102789), is a research vessel owned by the estate of Microsoft co-founder Paul Allen. The ship is named after the sea bird petrel. In 2016, Allen purchased the offshore service vessel form ...
captured video footage of the shark lurking around a World War II shipwreck in Ormoc Bay
Ormoc Bay is a large bay in the island of Leyte in the Philippines. The bay is an extension of the Camotes Sea. The city of Ormoc lies at the head of the bay and exports rice, copra and sugar.
The World War II Battle of Ormoc Bay took place fr ...
. This was the first time the species was photographed in Philippine waters. In 2018, a sixgill shark was filmed near the Saint Peter and Saint Paul Archipelago
The Saint Peter and Saint Paul Archipelago ( pt, Arquipélago de São Pedro e São Paulo ) is a group of 15 small islets and rocks in the central equatorial Atlantic Ocean. , midway between Brazil and Africa, at a depth of around . In 2019, the remains of a pregnant bluntnose sixgill shark were found on a Vancouver Island
Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian Provinces and territories of Canada, province of British Columbia. The island is in length, in width at its widest point, and in total area, while are o ...
beach, north of Victoria
Victoria most commonly refers to:
* Victoria (Australia), a state of the Commonwealth of Australia
* Victoria, British Columbia, provincial capital of British Columbia, Canada
* Victoria (mythology), Roman goddess of Victory
* Victoria, Seychelle ...
, British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
. On 18 October 2019, a large bluntnose sixgill shark measuring over and weighing was found dead on the beach at Urkmez beach in Seferihisar
Seferihisar is a coastal district and the center town of the same district in İzmir Province, in Turkey. Seferihisar district area borders on other İzmir districts of Urla to the west and Menderes ( Cumaovası) to the east, and touches İzmir's ...
, Izmir, Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
.
Being in such a deep area of the ocean, these sharks have developed the behavior of undergoing diel vertical migration
Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The word ''diel'' comes from the Latin ''dies'' day, and means a 24-h ...
(DVM) in order to have more access to food. Research has found that it takes more time for the sixgills to have to swim back down to their natural habitat of the bathypelagic rather than to swim up during the night to find food in the more populated zones. As such, it can be inferred that they have some sort of adaptation that aids buoyancy to ensure that these sharks are able to float more easily. An example of this DVM occurrence was found off the coast of Oahu
Oahu () (Hawaiian language, Hawaiian: ''Oʻahu'' ()), also known as "The Gathering place#Island of Oʻahu as The Gathering Place, Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over t ...
, Hawaii, whereby 4 sixgills' behaviors were studied. At around midnight to 3–am, the 4 sharks swam up to a minimum depth of whereas at about noon, they reached their maximum depth of between to . This shows a daily pattern whereby the sixgills are going up during the nights when it is darker and colder to forage for food up in the shallower depths but as morning comes and light and higher temperatures starts to come in more intently again, the sharks go back down to their original habitat to maintain a lower metabolic rate, ensuring that they will be able to use the nutrients from whatever they ate during the night slowly, reducing the need for them to search for more food throughout the day. Another study found that the motivating factor for the bluntnose sixgill sharks' DVM behavior was foraging. Researchers were able to rule out predator and competitor avoidance as potential reasons for the vertical movement patterns because they found pairs of sharks with synchronized movements, indicating that the sharks were responding to the same stimuli. The sharks demonstrated distinct and consistent patterns of vertical migration despite size, sex, and spatial scales, showing that foraging behavior can most likely be seen as the reason for the diel vertical patterns of sixgill sharks. Lastly, the bluntnose sixgill shark has consistent seasonal movements. They move north during the winter and spring and south during the summer and fall. In this study as well, researchers were able to determine that these movement patterns can be attributed to the seasonal movements of prey over other reasons.
Feeding behavior
Sixgill sharks possess variability in their feeding mechanisms that could have contributed to their evolutionary success and global distribution. These sharks are able to protrude their jaws and vary their methods of feeding depending on the situation. They utilize sawing and lateral tearing techniques to manipulate food. Sixgill sharks also lower their pectoral fins right before they strike in order to stop forward progressions, making it easier for them to forage.
Biology and ecology
Although sluggish in nature, the bluntnose sixgill shark is capable of attaining high speeds for chasing and catching its prey using its powerful tail. Because of its broad range, it has a wide variety of prey, including fish
Fish are aquatic, craniate, gill-bearing 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. Approximately 95% of li ...
, rays
Ray may refer to:
Fish
* Ray (fish), any cartilaginous fish of the superorder Batoidea
* Ray (fish fin anatomy), a bony or horny spine on a fin
Science and mathematics
* Ray (geometry), half of a line proceeding from an initial point
* Ray (gra ...
, chimaera
Chimaeras are cartilaginous fish in the order Chimaeriformes , known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.
At ...
s, squid
True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...
, crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
s, shrimp
Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...
s, seals
Seals may refer to:
* Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly:
** Earless seal, or "true seal"
** Fur seal
* Seal (emblem), a device to impress an emblem, used as a means of a ...
, and other (smaller) shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
s. The bluntnose sixgill shark is therefore classified as a generalist species, and is less likely to be affected by scarcity in any one of its food sources. A study done in 1986, with 28 sixgills, discovered that the most abundant meal they were able to obtain include cartilaginous and bony fishes, followed by marine mammals and several invertebrates. As time passes, however, it seems that their stomach contents have changed. In 1994, it was found that of 137 samples, the major prey groups were cephalopod
A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...
s, teleost fishes, chondrichthyans
Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. C ...
and marine mammal
Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and polar bears. They are an informal group, unified only by their reli ...
s. This difference in results could be due to several reasons. Firstly, as noticed in the different sample sizes of the two studies, it could be due to technology back then not being advanced enough to fully study the stomach contents and capture enough samples, leading to a skewed result for the 1986 study. Next, as human activities have increased over the years, it could affect the availability of food for the sixgills in the deep. There are other potential reasons for this change in diet, many factors may have affected the sixgills.
Bluntnose sixgill sharks are also positively buoyant as hypothesized earlier. During vertical movements, the sixgill sharks demonstrate more swimming efforts for the descent than the ascent. This is indicated by the greater number of tail beats and the sharks' ability to glide upwards for several minutes. The positive buoyancy can help the sharks to hunt stealthily by approaching prey from below undetected since the upward gliding permits minimal movement. It can also be advantageous for their diel vertical migrations. Since the sharks spend their days in colder water, their metabolic rates decline. Positive buoyancy can help them to glide upwards with minimal swimming involved during their evening migrations.
Reproduction is ovoviviparous
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...
with embryos receiving nourishment from a yolk sac while remaining inside the mother. Litters are large and typically have 22-108 pups measuring at birth,[ and the largest recorded pup is . New pups are also born with a lighter belly color than adults. This form of ]cryptic coloration
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
or camouflage
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...
is used to disguise the pup's appearance. A high mortality rate of the young pups is presumed, owing to the large litter size. The gestation period is unknown, but is probably more than two years, based on the gestation time of other hexanchiform sharks like the frilled sharks. Females reach sexual maturity at in length[ and 18–35 years in age, while males reach sexual maturity much earlier at in size] and 11–14 years in age. Many biologists believe that the male bluntnose sixgill shark's teeth are specially adapted for courtship. The male nips at the female's gill slits using its longer-cusped teeth. This action is thought to entice the female into mating. Evidence of this hypothesis
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...
is that female bluntnose sixgill sharks show up with seasonal scars around their gill slits, which apparently is from breeding with males. Males and females are thought to meet seasonally between May and November.
Human interaction
The bluntnose sixgill shark is listed as Near Threatened
A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...
by the International Union for Conservation of Nature
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
(IUCN) because, despite its extensive range, its longevity and popularity as a sport fish makes it vulnerable to exploitation and unable to sustain targeted fishing for very long. Although population data is lacking in many areas for this species, certain regional populations have been classified as severely depleted. Although it is usually caught as bycatch, it is also caught for food and sport. In June 2018, the New Zealand Department of Conservation
An environmental ministry is a national or subnational government agency politically responsible for the environment and/or natural resources. Various other names are commonly used to identify such agencies, such as Ministry of the Environment ...
classified the bluntnose sixgill 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 some ...
.
Despite its massive size, this species is rather harmless to humans unless provoked.[
]
Recent research
''Blue Planet II''
''Blue Planet II
''Blue Planet II'' is a 2017 British nature documentary series on marine life produced by the BBC Natural History Unit. Like its predecessor, ''The Blue Planet'' (2001), it is narrated and presented by naturalist Sir David Attenborough.
After ...
'', a documentary on marine organisms produced by the BBC, featured an episode focussing on deep sea organisms and environments. In this episode, bluntnose sixgill sharks were filmed feeding on a whale fall. In behind-the-scenes footage, the sharks attacked the deep sea submersible as crew members tried to collect the video footage. Thinking that they were competition, the sharks used their bodies to try to fend off the submarine, only leaving it behind once they realized that the sub was not there to feed
The film crew was able to obtain useful video footage of the sixgills that they later featured in the episode. As a worldwide, well-known, scientific platform, it hence helped with the awareness of the existence of these species of sharks.
Tagging sixgills in their natural habitat
Since 2005, scientists have successfully been able to tag sixgill sharks as a means of studying their behavior. With this being said, however, as of 2019, there has yet to be a sixgill tagged in its natural deep-sea habitat. Researchers from Florida State University, the Florida Museum of Natural History
The Florida Museum of Natural History (FLMNH) is Florida's official state-sponsored and chartered natural-history museum. Its main facilities are located at 3215 Hull Road on the campus of the University of Florida in Gainesville.
The main pub ...
, the Cape Eleuthera Institute, and OceanX
OceanX is an ocean exploration initiative founded by Mark Dalio and Ray Dalio, founder of investment firm Bridgewater Associates, An initiative by Dalio Philanthropies, OceanX is a “mission to explore the ocean and bring it back to the world. O ...
hence decided to join forces to tag a deep-sea shark through use of a submersible, and they succeeded in doing so. After 3 months of leaving the tag on the sixgill, the tag was thought to float up to the surface where scientists will be able to collect the data from that tag. Overall, this study showed how advancements in technology has helped scientists be better able to study marine life. Instead of having to go on an expedition for years at a time, the scientists here simply had to attach a tag onto the sixgill once and collect the data another time. The tag simply showed behavioral results of the sixgills.
References
External links
*
*
*
Information on ''H. griseus''
from ReefQuest Center for Shark Research
YouTube video (1:17)
- 18' specimen filmed at 1000 m in Molokai, HI.
YouTube Video 1:37 - Cape Eleuthera Institute
BBC Video 1:54
multiple specimens feeding at 750 m
{{DEFAULTSORT:Bluntnose Sixgill Shark
Hexanchus
Fish described in 1788
Taxa named by Pierre Joseph Bonnaterre