Greenland Shark Adult
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 native to the waters of the North Atlantic Ocean around Greenland and Iceland. These sharks live farther north than any other shark species. They are closely related to the Pacific sleeper shark.
This is one of the largest species of shark, of dimensions comparable to those of the great white shark. Large Greenland sharks grow to 6.4 metres (21 ft) and 1,000 kilograms (2,200 lb), and possibly up to 7.3 metres (24 ft) and more than 1,400 kilograms (3,100 lb). However, most Greenland sharks observed have been around 3–4.8 metres (9.8–15.7 ft) long and weigh up to 400 kilograms (880 lb). It rivals the Pacific sleeper shark (possibly up to 7 m or 23 ft long) as the largest species in the family Somniosidae. There are no reliable data on their life span, but fully grown Greenland sharks have been recaptured 16 years after being tagged.
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.
Greenland Shark Baby
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, producing effects similar to extreme drunkenness. Occasionally, sled dogs 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, but not in most other shark species, whose meat is often consumed fresh.