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Greenland sharks are widely recognized as the world’s longest-lived vertebrates, with an estimated lifespan of around 250 to 500 years. But that’s not the only incredible thing about them.
Greenland sharks are native to the North Atlantic and Arctic Oceans, where they are apex predators that feed on a variety of fish, other sharks, squid, and seals, both as scavengers and as active predators. The largest members of the species reach lengths of up to 23 feet (7 m), though many are significantly smaller.
Greenland sharks are almost entirely blind, as their eyeballs are often covered with small parasitic crustaceans called copepods, yet they are still remarkable hunters. Instead of using their eyes, they rely on their keen senses of smell and hearing. After all, Greenland sharks spend nearly all of their time hunting in near-darkness. They prefer ocean environments with cold water temperatures and can be found at depths of up to 4,900 feet (1,500 m).
Amazingly, the top speed of a Greenland shark is just 1.6 miles per hour (2.6 km/hr), leaving scientists wondering how they catch seals, which are much faster swimmers. An ambush method has been hypothesized.
An ocean enigma that's likely to outlive you:
- A landmark study of 28 female Greenland sharks in 2016 finally shed light on the species’ longevity, though their very slow growth rates (less than one centimeter per year) had always suggested a long lifespan. Radiocarbon dating was used to estimate the age of Greenland sharks based on the protein that builds up on the lenses of their eyes. Remarkably, scientists also relied on increased levels of carbon-14 due to 1950s nuclear testing to accurately determine the age of the sharks.
- It has been estimated that female Greenland sharks don’t reach sexual maturity until well into their second century, possibly around 150 years old. Their gestation period is thought to be somewhere between 8 and 18 years. Even so, due to their unparalleled lifespan, they may ultimately give birth to hundreds of “pups.”
- Dried and fermented Greenland shark meat, known as kæstur hákarl, is a delicacy in Iceland. However, the fresh flesh of the shark is toxic due to its high content of trimethylamine N-oxide (TMAO), a nitrogenous compound that helps the shark stay buoyant and endure the deep-water pressure.