Greenland shark

Greenland Shark

The Greenland shark (Somniosus microcephalus), also known as the gurry shark, or grey shark, is a large shark species found in the North Atlantic and Arctic Oceans. This species is notable for its extreme longevity, with some individuals believed to live for more than 400 years, making it the longest-living vertebrate known on Earth.

Description

The Greenland shark is one of the largest living species of shark, with adult females typically reaching lengths of 2.44–4.8 meters (8.0–15.7 ft) and males measuring slightly smaller. The body of the Greenland shark is robust and cylindrical, with a short, rounded snout and small eyes. Its coloration ranges from dark brown to blackish-gray, providing camouflage in the deep, cold waters it inhabits.

Habitat and Distribution

Greenland sharks are found in the cold, deep waters of the North Atlantic and Arctic Oceans, from the eastern coast of Canada to Norway and Iceland. They are known to dwell at depths of up to 2,200 meters (7,200 ft), though they are occasionally found near the surface in colder regions. Their preference for cold environments means they are rarely seen in waters where the temperature exceeds 10°C (50°F).

Diet

The diet of the Greenland shark is varied and includes fish, squid, and larger mammals such as seals. They are also known to scavenge, feeding on the carcasses of dead animals that sink to the ocean floor. Despite their size and predatory nature, there is little evidence to suggest that Greenland sharks pose a significant threat to humans.

Reproduction

Little is known about the reproduction of Greenland sharks. They are thought to be ovoviviparous, with embryos developing inside the female's body until they are born. The gestation period is believed to be very long, possibly as much as 18 years, contributing to the shark's slow rate of reproduction.

Conservation

The Greenland shark is currently listed as "Near Threatened" by the International Union for Conservation of Nature (IUCN). While not heavily fished, they are sometimes caught as bycatch in commercial fishing operations. Their slow growth rate, late maturity, and long gestation period make them particularly vulnerable to overfishing.

Cultural Significance

In Inuit culture, the Greenland shark has been an important source of food, though its flesh is toxic when fresh due to high levels of urea and trimethylamine oxide. It must be properly processed, traditionally by fermenting it for several months, to be safe for consumption. This fermented shark meat, known as hákarl, is considered a delicacy in Iceland.

Research and Longevity

Recent research into the Greenland shark's longevity has garnered significant scientific interest. Studies estimating the age of these sharks through radiocarbon dating of eye lens proteins suggest they can live for centuries, with the oldest recorded individual estimated to be nearly 400 years old. This remarkable lifespan has prompted further studies into the shark's biology and genetics, with the hope of uncovering the secrets behind its longevity.

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