I have dived with lemon sharks, wobbegongs, whitetip reef sharks and hammerheads. I have never seen a Greenland shark. Almost nobody has.
Greenland sharks live primarily in the Arctic and North Atlantic Oceans, in dark water near freezing. They swim slower than you walk. And the big ones were probably born before Isaac Newton.
I studied marine biology on exchange at Uppsala in Sweden. They live off Sweden’s west coast, in the deep Skagerrak, where SLU researchers tracked them in 2024.
On our lap around Australia, a spotted wobbegong lay still on the sand while we snorkelled Minnie Water, near Illaroo. The Greenland shark lives the other extreme. Here is what we know, updated with new research from 2026.
Greenland Shark Quick Facts
- Scientific name: Somniosus microcephalus, once called Squalus borealis and Scymnus glacialis
- Family: Somniosidae, the sleeper sharks
- Lifespan: about 250 to 500 years. The oldest is estimated at 392 years.
- Sexual maturity: about 150 years
- Growth: 0.5 to 1 cm per year
- Size: usually 2 to 5.5 m, over 1,000 kg
- Speed: 0.34 m/s on average
- Depth: to 2,200 metres and beyond
- Water: mostly −1 to 7°C
- Status: Vulnerable (IUCN). About 3,500 caught as bycatch each year.
1. They Are the Longest-Living Vertebrate Known
Greenland sharks are considered the longest-living vertebrate known to science. They can live between about 250 and 500 years.
In a 2016 study in Science, University of Copenhagen researchers aged 28 females. The oldest Greenland shark is estimated to be 392 years old, give or take 120.
That beats the bowhead whale, the longest-lived mammal at over 200 years. See how others compare in the animals that live the longest.
Their soft vertebrae have no growth bands to count, so scientists use radiocarbon dating of eye lens proteins instead.
The lens centre forms before birth and never changes, so it records the shark’s birth year. Carbon-14 from 1950s bomb tests helped calibrate the ages.
2. They Reach Sexual Maturity at About 150 Years
Greenland sharks have a slow growth rate and late maturity. They grow just 0.5 to 1 cm per year. Females reach sexual maturity at about 150 years, once they pass 4 m.
Their gestation period is thought to be long, possibly several years. One female carried 10 near-term pups.
That slow life limits recovery from overfishing. A female caught at 120 years old has never bred.
3. They Are the Slowest Fish Ever Measured
Greenland sharks have a very slow metabolism, and it shows. Their average swimming speed is 0.34 m/s, about 1.2 km/h. That is slower than a stroll.
Tags fitted in Svalbard in 2012 showed one tail beat every seven seconds. That earned them old nicknames: sleeper sharks and the gurry shark.
Cold water explains it: at 1°C, everything slows down. Compare that with the fastest sea animals.
4. They Hunt Seals and Scavenge Carrion
Greenland sharks are opportunistic scavengers and can also hunt seals and fish. They primarily eat fish and seals. Their flexible diet includes fish, squid and carrion.
A shark this slow should not catch seals, yet fresh, whole seals turn up in their stomachs. They may ambush seals sleeping in the water.
They are also thought to use suction to draw in prey. Neither trick has been filmed in the wild.
They are known to scavenge on carrion too. They have been found with remains of moose and reindeer, plus polar bear tissue and other marine mammals. Old fishing stories even mention a human leg, never confirmed.
Cod, wolffish and Greenland halibut are key prey. This feeding ecology makes them both Arctic apex predators and clean-up crew, an important part of the marine food web.
5. Their Eyes Are Adapted for Low Light
Most adult Greenland sharks are infested with copepod parasites on their corneas. The copepod, Ommatokoita elongata, hangs from the eye like a pale streamer. Parasitic copepods are among the best-known fish diseases, but few are this visible.
Barely scientifically investigated, the eyes were long called “functionally blind”. A new study in January 2026 proved otherwise.
Greenland sharks can live in dark conditions and have vision adapted for low light. Researchers at the University of Basel and UC Irvine examined sharks aged 100 to 134 years. Their retinas were healthy, packed with rods and tuned to blue light.
Active DNA repair genes may keep the retina working for centuries. The parasite may blur the view, but it does not switch it off. Claims that the copepods glow as a lure are untested. For animals that really make light, see bioluminescent animals.
6. Their Body Is Built for the Cold, Not for Speed
Forget the torpedo shape of a great white. A Greenland shark is thick and grey-brown, with a short, rounded snout and small eyes. Microcephalus means “small head”.
The fins are small, with low dorsal fins, short pectoral fins and no anal fin. The gill openings are small for such a big fish.
The upper teeth are narrow spikes with smooth cusps, for gripping. The lower teeth are broad blades whose cusps point outward. The shark bites, then rolls its head to carve a chunk, like the cookiecutter shark.
The salmon shark beats the cold by keeping its body warm. This one simply goes cold with the sea.
7. They Are One of the Biggest Sharks Alive
Most measure 2 to 4 m, and females reach 5 to 5.5 m. Older reports say they can grow to lengths of up to 21 to 23 feet, but those were never verified. A big female can weigh over 1,000 kg.
That puts them among the biggest fish in the world. Only a few other sharks, like the whale shark, grow bigger. All fall well short of the long-gone megalodon. Want to see it to scale?
Interactive · free Shark size comparison Twenty sharks at true scale, from a 27 cm pygmy shark to a 15 m megalodon, each beside a 2 m diver. Pit any two head to head, or test your eye in the guessing game. Compare the sharks →
8. They Live in Cold, Deep Water Near Freezing
Greenland sharks have a remarkable ability to survive in cold deep waters near freezing temperatures. They mostly live in water between about −1 and 7°C.
They can dive to depths of 2,200 metres. Canada’s 2025 status report lists records close to 2,900 m. In the high Arctic, they also come up into shallow water, even under the ice.
That is deep, but not the bottom of the ocean. The hadal zone starts far deeper. Meet the animals sharing their deep sea environments in animals in the deep sea.
DEPTH1,110
m Interactive · Deep Sea Dive Dive 1,110 m down to meet the Greenland shark Scroll from the surface to the Mariana Trench and log 61 ocean animals on the way. →
9. They Are the Only Sharks That Live in the Arctic Year-Round
Of more than 500 shark species, Greenland sharks are the only sharks known to tolerate Arctic conditions year-round. They live in Greenland waters, around Iceland and Svalbard, off Norway and down Canada’s east coast.
In Arctic Canada, communities around Pond Inlet and Cumberland Sound fish Greenland halibut through the ice. The sharks often end up on the lines.
10. Greenland Shark Meat Is Toxic Until It Is Fermented
Their flesh and tissues contain high concentrations of urea and trimethylamine oxide (TMAO). These keep the shark’s body fluids balanced and protect its proteins under pressure.
Greenland shark meat is toxic due to TMAO levels. Digestion turns TMAO into trimethylamine, and eating the meat can cause severe intoxication symptoms. Dogs can become incapacitated after eating Greenland shark meat, staggering as if drunk.
Fermentation removes the toxins, making the meat safe to eat. Greenland shark meat is traditionally prepared as hákarl in Iceland. The fermentation process takes six to twelve weeks, then the meat hangs to dry for months.
11. A Slow Metabolism Helps Them Live So Long
Greenland sharks have a slow metabolism contributing to their longevity. Every chemical reaction runs slower at 1°C, including the ones that damage cells.
But other cold-water fish don’t live 400 years, so the secret goes deeper. They appear to carry DNA repair genes that help maintain tissue integrity.
In May 2026, a University of Tokyo team published its genome in PNAS. At 5.9 billion base pairs, it is nearly twice the size of ours. Gene families linked to DNA repair and immunity appear expanded.
Add the healthy retinas, and a picture forms: these sharks repair damage well, for centuries. It remains one of the big questions in polar biology and fish biology.
12. They Are Vulnerable, and Still Being Caught
Greenland sharks are listed as Vulnerable by the IUCN. In 2025, Canada’s COSEWIC also assessed them as Special Concern.
They are primarily caught as bycatch in industrial fisheries. About 3,500 Greenland sharks are caught annually as bycatch, in trawls, longlines and gill nets. However, the real number is probably higher.
In the past, fishers hunted them for liver oil and landed tens of thousands in some years. Then in 2022, NAFO banned keeping them in international Northwest Atlantic waters. In October 2026, a north Greenland council approved culling 1,000 sharks over damaged fishing gear. However, Greenland’s fisheries ministry questioned its legal basis, so the council dropped the plan.
Warmer temperatures add pressure too. See other endangered sea animals and how marine protected areas help.
Frequently Asked Questions About Greenland Sharks
They can live between about 250 and 500 years. The oldest is estimated at 392 years.
No. Most carry copepod parasites on their corneas, but a 2026 study found their retinas healthy and adapted for low light.
There are no confirmed attacks on people. They live deep and cold, so encounters are rare.
Not fresh. The meat is toxic due to TMAO. Fermented and dried as hákarl in Iceland, it is safe to eat.
Very few people do. Some divers see them under the ice in Arctic Canada. For warm-water dives, see the best places to swim with sharks.
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References:
Costantini, D., Smith, S., Killen, S. S., Nielsen, J., & Steffensen, J. F. (2017). The Greenland shark: A new challenge for the oxidative stress theory of ageing? Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 203, 227–232. https://doi.org/10.1016/j.cbpa.2016.09.026
Edwards, J. E., et al., (2019). Advancing research for the management of long-lived species: A case study on the Greenland shark. Frontiers in Marine Science, 6, 87. https://doi.org/10.3389/fmars.2019.00087
Fogg, L. G., Tom, E., Policarpo, M., Cho, W., Gao, F., Hii, D., Fawcett, A. E., Boileau, N., Bech-Poulsen, A., Steffensen, K. F., Ng, C. J., Bushnell, P. G., Steffensen, J. F., Brill, R., Salzburger, W., & Skowronska-Krawczyk, D. (2026). The visual system of the longest-living vertebrate, the Greenland shark. Nature Communications, 17, 39. https://doi.org/10.1038/s41467-025-67429-6
Nielsen, J., Hedeholm, R. B., Heinemeier, J., Bushnell, P. G., Christiansen, J. S., Olsen, J., Ramsey, C. B., Brill, R. W., Simon, M., Steffensen, K. F., & Steffensen, J. F. (2016). Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus). Science, 353(6300), 702–704. https://doi.org/10.1126/science.aaf1703
Watanabe, Y. Y., Lydersen, C., Fisk, A. T., & Kovacs, K. M. (2012). The slowest fish: Swim speed and tail-beat frequency of Greenland sharks. Journal of Experimental Marine Biology and Ecology, 426–427, 5–11. https://doi.org/10.1016/j.jembe.2012.04.021
Yang, K., Nishiwaki, K., Mizobata, H., Liang, J., Asakawa, S., Yoshitake, K., Watanabe, Y. Y., Hussey, N. E., Kovacs, K. M., Lydersen, C., Kadota, M., Kuraku, S., & Kinoshita, S. (2026). The Greenland shark genome: Insights into lifespan extremes and population dynamics. Proceedings of the National Academy of Sciences, 123(21), e2601272123. https://doi.org/10.1073/pnas.2601272123
