The Greenland shark (Somniosus microcephalus), also known as the gurry shark, grey shark, is a large shark of the family Somniosidae (“sleeper sharks”).
The Greenland shark also has an Inuit name, since it plays an important role in the Inuit culture. They call the Greenland shark “Eqalussuaq.”
Greenland sharks are mostly found in the cold-water environments of the North Atlantic Ocean and Arctic Ocean.
Greenland sharks have the longest known lifespan of all vertebrate species – between 300 and 500 years.
The Greenland shark is one of the largest sharks. It can reach a length of 7 meters (23 feet) and a weight of 1,025 kg (2,260 pounds) when fully grown, but most are between 2.5 and 4.8 meters (8.2 and 15.8 feet).
Coloration can range from pale creamy-gray to blackish-brown and the body is typically uniform in color, though whitish spots or faint dark streaks are occasionally seen on the back.
The snout is short and rounded, and the body is heavy and cylindrical in shape with small precaudal fins.
This shark is an extremely slow growing animal. One Greenland shark was tagged off the coast of Greenland in 1936 and recaptured in 1952. Its measurements suggest that Greenland sharks grow at a rate of 0.5 to 1 cm (0.2 to 0.4 in) per year.
Greenland sharks are rarely encountered by humans. They are thought to prefer colder, deeper environments but may be found anywhere between the sea surface and depths of 2,200 meters (about 7,200 feet).
During the summer the Greenland shark usually inhabits depths of 180 to 730 meters (600 to 2400 feet). In the winter, it can be found near the surface and near the edge of ice flows.
The Greenland shark is slow-moving; It swims at a leisurely 1.22 km/h (0.76 mph), with its fastest cruising speed only reaching 2.6 km/h (1.6 mph).
The Greenland shark is an apex predator and mostly eats fish including smaller sharks, skates, eels, herring, capelin, Arctic char, cod, rosefish, sculpins, lumpfish, wolffish, and flounder.
When captured Greenland sharks have been found with remains of seals, polar bears, horses, moose, and reindeer (in one case an entire reindeer body) in their stomachs.
The Greenland shark is ovoviviparous – producing young by means of eggs which are hatched within the body of the female.
The Greenland shark can have litters of up to 10 pups. The young are born at a size of 38 cm (15 in).
There are no known predators of adult Greenland sharks because of their very large size.
The species is considered near threatened by the IUCN.
The species was valued for its liver oil; about 114 liters (30 gallons) of liver oil can be obtained from a large specimen.
Greenland sharks were fished commercially from the 19th century until 1960.
In the early 1900s as many as 30,000 Greenland sharks were caught a year. In the present day the annual take is far smaller; small-scale subsistence fisheries in the Arctic harvest fewer than 100 individuals annually, and roughly 1,200 are caught accidentally in fishing trawls.
Although the flesh of the Greenland shark may be eaten, it is toxic unless properly cleaned and dried or repeatedly boiled prior to consumption. It is considered a delicacy in Iceland.
Greenland sharks are not considered dangerous to humans, in part because they live in regions where people do not typically swim; the only known report of a possible attack by a Greenland shark on a person dates to 1859.