Greenland shark

Greenland shark

Discussion
Ask a question about 'Greenland shark'
Start a new discussion about 'Greenland shark'
Answer questions from other users
Full Discussion Forum
 
Encyclopedia
The Greenland shark, Somniosus microcephalus, also known as the sleeper shark, gurry shark, ground shark, grey shark, or by the Inuit languages name Eqalussuaq, is a large shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

 native to the waters of the North Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 around Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

 and Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...

. These sharks live farther north than any other shark species. They are closely related to the Pacific sleeper shark
Pacific sleeper shark
The Pacific sleeper shark, Somniosus pacificus, is a sleeper shark of the family Somniosidae, found circumglobally on continental shelves and slopes in temperate waters between latitudes 70°N and 47°S, from the surface to...

. This is one of the largest species of shark, of dimensions comparable to those of the great white shark
Great white shark
The great white shark, scientific name Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached...

. Large Greenland sharks grow to 6.4 metres (21 ft) and 1000 kilograms (2,204.6 lb), and possibly up to 7.3 metres (24 ft) and more than 1400 kilograms (3,086.5 lb). However, most greenland sharks observed have been around 3–4.8 m (9.8–15.7 ft) long and weigh up to 400 kilograms (881.8 lb). It rivals the Pacific sleeper shark
Pacific sleeper shark
The Pacific sleeper shark, Somniosus pacificus, is a sleeper shark of the family Somniosidae, found circumglobally on continental shelves and slopes in temperate waters between latitudes 70°N and 47°S, from the surface to...

 (possibly up to 7 m or 23 ft long) as the largest species in the family Somniosidae
Somniosidae
Somniosidae is a family of sharks in the order Squaliformes, commonly known as sleeper sharks.-Genera:* Centroscymnus Barbosa du Bocage & Brito Capello, 1864...

. The Greenland shark is known to be long-lived, with an estimated maximum life span of over 200 years.

Lifestyle


The Greenland shark is an apex predator
Apex predator
Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...

 mostly eating fish, though it may also prey on marine mammals such as seals
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...

. Bite marks on dead seals at Sable Island
Sable Island
Sable Island is a small Canadian island situated 300 km southeast of mainland Nova Scotia in the Atlantic Ocean. The island is a year-round home to approximately five people...

, Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...

 and Hawarden
Hawarden
Hawarden is a village in Flintshire, North Wales. Hawarden forms part of the Deeside conurbation on the Welsh/English border. At the 2001 Census, the population of Hawarden Ward was 1,858...

 suggest that this shark may be a major predator for them in the winter months. Greenland sharks have also been found with remains of polar bear
Polar Bear
The polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak Bear, which is approximately the same size...

 and reindeer
Reindeer
The reindeer , also known as the caribou in North America, is a deer from the Arctic and Subarctic, including both resident and migratory populations. While overall widespread and numerous, some of its subspecies are rare and one has already gone extinct.Reindeer vary considerably in color and size...

 in their stomachs. The greenland shark is also known to be a scavenger and to what extent carrion (almost certainly the origin of the reindeer) figures into the slow-moving fish's stomach contents is unknown. The shark is colonized by the parasitic copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

 Ommatokoita elongata that eats the shark's cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...

l tissue. The Shark occupies what tends to be a very deep environment seeking its preferable cold water (-0.6 to + 10 °C) habitat. It has been observed at depths of 2200m by a submersible investigating the wreck of the SS Central America
SS Central America
SS Central America, sometimes called the Ship of Gold, was a 280-foot sidewheel steamer that operated between Central America and the eastern coast of the United States during the 1850s. She was originally named the SS George Law, after Mr. George Law of New York...

.

Reproduction


As recently as 1957 it was found that the females do not deposit eggs in the bottom ooze, but retain the developing embryos within their bodies so that they are born alive after an undetermined gestation period. 10 pups per litter is the norm, each measuring some 90 centimetres in length.

Greenland sharks as food


The flesh of a Greenland shark is poisonous. This is due to the presence of the toxin trimethylamine oxide, which, upon digestion, breaks down into trimethylamine
Trimethylamine
Trimethylamine is an organic compound with the formula N3. This colorless, hygroscopic, and flammable tertiary amine has a strong "fishy" odor in low concentrations and an ammonia-like odor at higher concentrations...

, producing effects similar to extreme drunkenness. Occasionally, sled dog
Sled dog
Sled dogs, known also as sleigh man dogs, sledge dogs, or sleddogs, are highly trained types of dogs that are used to pull a dog sled, a wheel-less vehicle on runners also called a sled or sleigh, over snow or ice, by means of harnesses and lines.Sled dogs have become a popular winter recreation...

s that end up eating the flesh are unable to stand up due to the neurotoxins. Similar toxic effects occur with the related Pacific sleeper shark
Pacific sleeper shark
The Pacific sleeper shark, Somniosus pacificus, is a sleeper shark of the family Somniosidae, found circumglobally on continental shelves and slopes in temperate waters between latitudes 70°N and 47°S, from the surface to...

, but not in most other shark species, whose meat is often consumed fresh.

However, it can be eaten if it is boiled in several changes of water or dried or fermented for some months
Hákarl
Hákarl or kæstur hákarl is a food from Iceland. It is a Greenland or basking shark which has been cured with a particular fermentation process and hung to dry for four to five months...

 to produce Kæstur Hákarl
Hákarl
Hákarl or kæstur hákarl is a food from Iceland. It is a Greenland or basking shark which has been cured with a particular fermentation process and hung to dry for four to five months...

, often Hákarl for short. Traditionally this was done by burying the shark in boreal ground, exposing it to several cycles of freezing and thawing. It is considered a delicacy in Iceland and Greenland.

Inuit legends


The shark is not considered to be dangerous to humans, though there are Inuit
Inuit
The Inuit are a group of culturally similar indigenous peoples inhabiting the Arctic regions of Canada , Denmark , Russia and the United States . Inuit means “the people” in the Inuktitut language...

 legends of this species attacking kayak
Kayak
A kayak is a small, relatively narrow, human-powered boat primarily designed to be manually propelled by means of a double blade paddle.The traditional kayak has a covered deck and one or more cockpits, each seating one paddler...

s.

The Greenland shark's poisonous flesh has a high urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

 content, which gave rise to the Inuit legend of Skalugsuak, the first Greenland shark. The legend says that an old woman washed her hair in urine and dried it with a cloth. The cloth blew into the ocean to become Skalugsuak.

Another legend is that of Sedna
Sedna (mythology)
In Inuit mythology, Sedna is the goddess of the sea and marine animals such as seals. A creation myth, the story of Sedna shows how she came to rule over Adlivun, the Inuit underworld...

, a girl whose father cut off her fingers while drowning her. Each finger was said to have become a sea creature, including the Greenland shark.

Dentition



When feeding on large carcasses, the shark employs a rolling motion of its jaw. The teeth of the upper jaw act as anchor while the lower jaw does the cutting. Teeth in the two halves of the lower jaw are strongly pitched in opposite directions.

Research


The Greenland Shark and Elasmobranch Education and Research Group (GEERG) has been studying the Greenland shark in the Saguenay Fjord
Saguenay River
The Saguenay River is a major river of Quebec, Canada.It drains Lac Saint-Jean in the Laurentian Highlands, leaving at Alma and running east, and passes the city of Saguenay. It drains into the Saint Lawrence River at Tadoussac....

 and St. Lawrence Estuary
Gulf of Saint Lawrence
The Gulf of Saint Lawrence , the world's largest estuary, is the outlet of North America's Great Lakes via the Saint Lawrence River into the Atlantic Ocean...

 since 2001. The Greenland shark has repeatedly been documented (captured or washed ashore) in the Saguenay since at least 1888. Accidental captures and strandings have also been recorded in the St. Lawrence Estuary for over a century.

Current research conducted by GEERG involves the study of the behaviour of the Greenland shark by observing it underwater using scuba and video equipment and by placing acoustic and satellite tags (telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...

) on live specimens; however, overall very little is known about this mysterious species.

There is now an argument suggesting that the Greenland is responsible for 'Seal Ripping' attacks on grey seal
Grey Seal
The grey seal is found on both shores of the North Atlantic Ocean. It is a large seal of the family Phocidae or "true seals". It is the only species classified in the genus Halichoerus...

s. These attacks cause a corkscrew pattern of cuts and tears which spiral around a seal's body, following the grain of the collagen within the muscles and running at 45 degrees to the seal's body. Seal deaths have been occurring over larger territories, including the north and east coasts of the UK, which suggests that the Greenland may be moving beyond its traditional habitat range. However, recent research into the UK "corkscrew" seal deaths by the Sea Mammal Research Unit concluded that the UK seal deaths were unlikely to have been caused by predation from the Greenland shark, rather being caused by blunt mechanical trauma "consistent with the seals being drawn through a ducted propeller" that are found on
many ships.

External links