Natural history

The Greenland shark is one of the largest cartilaginous fishes. It can reach a length of 7 metres (23 feet) and a weight of 1,025 kg (2,260 pounds) when fully grown, but most are between 2 and 4 metres (6.5 and 13 feet). Little is known, however, about how the species reproduces. Females are thought to reach sexual maturity when they surpass the 4-metre (13-foot) mark in length, which takes approximately 150 years to achieve. They are ovoviviparous (that is, eggs are retained within the body until they hatch) and produce an average of 10 offspring at a time. The type, amount, and duration of parental care the young receive are unknown, but scientists speculate that, like other shark species, Greenland sharks are independent from birth. No other vertebrate known has a life span as long as this species; radiocarbon dating of isotopes in the shark’s eye-lens nuclei suggests that the oldest Greenland sharks may be more than 500 years old.

Study the long-lived Greenland sharks inhabiting the Arctic Ocean and North Atlantic Overview of the Greenland shark (Somniosus microcephalus), which is the longest-lived vertebrate known, with a life span of 400 years or more. Encyclopædia Britannica, Inc. See all videos for this article

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). Greenland sharks are slow-moving, typically swimming at rates of less than 3 km (about 1.9 miles) per hour. They are carnivorous, and their diet is often made up of several different types of fishes, including smaller sharks, eels, flounders, and sculpins. Crustaceans, seabirds, and carrion—as well as terrestrial mammals (such as horses and reindeer) that likely fell through the ice—have been found in stomach analyses of the species. 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.