Greenland sharks (Somniosus microcephalus) are the longest-living animals with a spine, and survive for as much as tons of of years within the deep, chilly waters of the Arctic and North Atlantic oceans. Greenland sharks belong to a household referred to as sleeper sharks, which transfer slowly and stealthily via the water.
These sharks sneak up on stay prey and scavenge a wide range of useless animals, together with different sharks, seals, drowned horses and polar bears. Greenland sharks not often encounter people and scientists nonetheless have a lot to study their existence.
How huge are Greenland sharks?
Greenland sharks develop as much as 24 ft (7.3 meters) lengthy and weigh as much as 2,645 kilos (1,200 kilograms), in line with the St. Lawrence Shark Observatory (ORS). That is longer than nice white sharks (Carcharodon carcharias), that are estimated to develop as much as 20 ft (6 m) lengthy. (Though unconfirmed experiences counsel they’ll attain 23 ft (7 m) in size, in line with the Florida Museum of Pure Historical past.)
Measurement: As much as 24 ft (7.3 m)
Life span: 272 years (estimate)
Conservation standing: Weak
Greenland sharks have cylindrical our bodies lined in teeth-like scales, referred to as dermal denticles. These specialised scales scale back drag and assist the sharks transfer extra silently via the water, in line with the ORS. The sharks might be black, brown, grey or a combination of all three colours, and so they might have spots.
A Greenland shark’s mouth accommodates 48 to 52 enamel in its higher jaw and 50 to 52 enamel in its decrease jaw. The higher enamel are pointed, to assist the sharks maintain on to bigger meals, whereas the decrease enamel are vast and curved sideways so the sharks can carve out spherical chunks of flesh from prey by transferring their head in a round movement, in line with the ORS.
Are Greenland sharks blind?
Ocean parasites referred to as Ommatokoita elongata can render Greenland sharks partially blind. Ommatokoita elongata connect themselves to the eyes of Greenland sharks and may develop as much as 1 inch (2.5 centimetres) lengthy, in line with the Encyclopedia of Life. The attention parasite tends to stay in simply one of many shark’s eyes in order that they normally do not go fully blind. As a result of the sharks rely extra on their different senses to catch prey at the hours of darkness ocean waters, the parasites do not appear to have an effect on the sharks a lot, in line with the Florida Museum of Pure Historical past.
How lengthy do Greenland sharks stay?
Greenland sharks’ precise life span is unknown. A 2016 examine printed within the journal Science estimated that Greenland sharks have a most life span of no less than 272 years, based mostly on evaluation of the sharks’ eye tissue. Researchers estimated that the oldest Greenland shark in that examine was about 392 years previous, however the estimate had a margin of error of 120 years, which led to hypothesis that Greenland sharks may stay to 512 years previous. The estimated vary hasn’t been verified.
“It is vital to bear in mind there’s some uncertainty with this estimate,” Julius Nielsen, co-author of the 2016 paper, beforehand advised Reside Science. “However even the bottom a part of the age vary — no less than 272 years — nonetheless makes Greenland sharks the longest-living vertebrate identified to science.”
Greenland sharks stay within the sluggish lane, with a high swimming pace of lower than 1.8 mph (2.9 km/h). In addition they develop slowly at lower than 0.4 inch (1 centimeter) per 12 months and have sluggish metabolisms, in line with the Nationwide Oceanic and Atmospheric Administration (NOAA). Scientists do not but understand how Greenland sharks stay so lengthy, however it might be linked to their sluggish lifestyle.
The place do Greenland sharks stay?
Greenland sharks stay within the Arctic and North Atlantic oceans from North America to Greenland and from Portugal to the East Siberian Sea, in line with the Worldwide Union for Conservation of Nature (IUCN). The sharks have a wide variety and might be discovered swimming from the floor right down to depths of 8,684 ft (2,647 m), the IUCN says.
Scientists nonetheless have a lot to study how Greenland sharks stay and reproduce. Feminine Greenland sharks give start to stay younger, referred to as pups, that hatch from tender eggs that females carry inside their our bodies. In a 2020 examine printed within the journal PLOS One, researchers estimated that Greenland sharks may give start to between 200 and 324 pups per being pregnant, relying on the dimensions of the shark. Greenland shark pups are simply 14 to 18 inches (35 to 45 centimeters) lengthy after they’re born. Nonetheless, little is understood about how Greenland shark pups spend their early lives or what number of survive to maturity.
What do Greenland sharks eat?
Greenland sharks have a diversified food regimen that features fish, different sharks, eels and marine mammals, akin to seals. They’ve additionally been discovered with drowned land animals, together with horses and reindeer, of their stomachs, and have been seen in massive numbers on the sea floor, feeding collectively on the stays of whales and fish killed by business whaling and fishing, in line with the College of Michigan’s Animal Variety Net (ADW).
Greenland shark taxonomy
Genus and species: Somniosus microcephalus
Scientists have even discovered a Greenland shark with the jaw of a younger polar bear (Ursus maritimus) in its abdomen, Reuters reported in 2008. The researchers had been not sure the way it bought there; however most shark consultants believed that the polar bear was probably already useless when the shark ate it, as stay polar bears are too harmful for the sharks to tackle. Researchers additionally discovered some polar bear muscle tissue and pores and skin within the abdomen of one other Greenland shark throughout a 2014 examine printed within the journal Polar Biology, and so they concluded that the bear was probably scavenged reasonably than hunted.
Does something eat Greenland sharks?
Greenland sharks are close to the highest of the meals chain, however sperm whales (Physeter macrocephalus) might hunt them. Chris Harvey-Clark, co-founder of the Greenland Shark and Elasmobranch Schooling and Analysis Group (GEERG, now the ORS), wrote in Capeia, a web based science communication journal, about recording a Greenland shark seemingly fleeing from the echolocation clicks of a foraging sperm whale.
Upon its dying, that very same echolocating sperm whale was discovered with its enamel worn right down to stumps, much like these of orcas (Orcinus orca) that feed on Pacific sleeper sharks (Somniosus pacificus). Greenland sharks are carefully associated to Pacific sleeper sharks and have equally robust pores and skin. To elucidate the sperm whale tooth put on and a fleeing Greenland shark, Harvey-Clark theorized that the sperm whale hunted Greenland sharks. Scientists have but to watch sperm whales searching these sharks elsewhere.
Are Greenland sharks harmful?
There are not any verified experiences of Greenland shark assaults on people. Nonetheless, some anecdotal proof means that such assaults may happen. GEERG divers noticed a Greenland shark “stalk” a group of divers. They’ve additionally seen Greenland sharks examine diver actions as in the event that they had been scouting seal prey, in line with the ORS. A Greenland shark was reportedly discovered with a human leg in its abdomen off Canada’s Baffin Island round 1859, however this report was not verified.
Is Greenland shark meat poisonous?
Untreated Greenland shark meat is poisonous to people. Their meat accommodates excessive ranges of trimethylamine oxide (TMAO), which breaks down into the toxic trimethylamine (TMA) compound throughout digestion, in line with a 1991 examine printed within the journal Toxicon. TMA may cause extreme intestinal issues and produces comparable results to extreme alcohol consumption.
Greenland shark meat is edible solely when dried. The dried meat is fed to sled canines in northern areas akin to Greenland, in line with the Florida Museum of Pure Historical past. The meat can be fermented and consumed by folks inIceland, the place the meals, referred to as Hákarl, is taken into account a delicacy.
Are Greenland sharks endangered?
The IUCN considers Greenland sharks to be susceptible to extinction. People killed Greenland sharks for his or her liver oil to make use of in lamps and different merchandise between the thirteenth and twentieth centuries. The business fishing of Greenland sharks for his or her oil ended by the Nineteen Sixties, which helped their inhabitants rebound. Nonetheless, Greenland sharks proceed to be caught and killed as bycatch, or animals that get pulled up by fishers alongside their meant catch, for instance, in massive nets dragged alongside the underside of the ocean meant to catch numerous fish. Many of the Greenland sharks eaten by people and fed to canines come from bycatch, though some sharks are focused on a small scale.
The Northwest Atlantic Fisheries Group (NAFO), an intergovernmental fishing science and administration physique, prohibits the direct fishing of Greenland sharks and seeks to scale back bycatch. The NAFO applies to most fisheries within the northwest Atlantic Ocean and consists of nations such because the U.S. and Canada. However thee IUCN recommends the event and enforcement of additional protections, akin to bycatch coverage, for Greenland sharks.
The IUCN estimates that the Greenland shark inhabitants has declined by 30% to 49% over the previous 450 years, or three shark generations. Nonetheless, this decline was estimated based mostly on a conservative Greenland shark life span of 150 years; the decline could possibly be a lot greater if the sharks have longer life spans and thus take longer to succeed in reproductive age and produce extra sharks. The worldwide Greenland shark inhabitants dimension is unknown. Local weather change can be hurting the species — for instance, by decreasing Arctic sea ice, which provides fishing fleets simpler entry to Greenland shark habitat.
Go to the Encyclopedia of Life web site for extra details about the place these sharks stay. The web site supplies an interactive map of Greenland shark observations world wide. You may see extra photographs and movies of Greenland sharks and different deep sea creatures on the NOAA Ocean Exploration web site. Getting ready Greenland shark meat for human consumption is an extended course of that we do not delve into on this web page. To search out out extra in regards to the course of, you’ll be able to watch this brief video on YouTube from Meals Insider.
There aren’t dependable books on Greenland sharks particularly, however for a common information to the world’s sharks, take a look at “Sharks of the World: A Full Information” (Princeton College Press, 2021).
- Alister Doyle, Reuters, “Polar bear eaten by shark: who’s high predator?” Aug. 11, 2008. https://www.reuters.com/article/us-arctic/polar-bear-eaten-by-shark-whos-top-predator-idUSLB66891920080811
- Anthoni et al. “Poisonings from flesh of the Greenland shark Somniosus microcephalus could also be resulting from trimethylamine,” Toxicon, Quantity 29, 1991. https://pubmed.ncbi.nlm.nih.gov/1801314/
- Chris Harvey-Clark, Capeia, “Unknown Monster, Dreamless Sleeper: the Greenland Shark II,” Aug. 12, 2017. https://beta.capeia.com/zoology/2017/06/14/unknown-monster-dreamless-sleeper-the-greenland-shark-ii
- Encyclopedia of Life, “Ommatokoita elongata.” https://eol.org/pages/1037051
- Florida Museum of Pure Historical past, “Carcharodon carcharias,” Oct. 18, 2018. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharodon-carcharias/
- Florida Museum of Pure Historical past, “Somniosus microcephalus,” Dec. 5, 2019. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/somniosus-microcephalus/
- Kulka et al. “Somniosus microcephalus, The IUCN Crimson Checklist of Threatened Species,” 2020. https://www.iucnredlist.org/species/60213/124452872
- Mills, P, Animal Variety Net, “Somniosus microcephalus,” 2006. https://animaldiversity.org/accounts/Somniosus_microcephalus/
- Mindy Weisberger, Reside Science, “Greenland Sharks Might Reside 400 Years,” Dec. 15, 2017. https://www.livescience.com/55736-greenland-sharks-longest-lived-vertebrates.html
- Nationwide Oceanic and Atmospheric Administration (NOAA), “How lengthy do Greenland sharks stay?” March 1, 2021. https://oceanservice.noaa.gov/information/greenland-shark.html
- Nielsen et al. “Assessing the reproductive biology of the Greenland shark (Somniosus microcephalus),” PLOS One, Quantity 15, Oct. 7, 2020. https://doi.org/10.1371/journal.pone.0238986
- Nielsen et al. “Distribution and feeding ecology of the Greenland shark (Somniosus microcephalus) in Greenland waters,” Polar Biology, Quantity 37, Oct. 10, 2013. https://hyperlink.springer.com/article/10.1007/s00300-013-1408-3
- Nielsen et al. “Eye lens radiocarbon reveals centuries of longevity within the Greenland shark (Somniosus microcephalus),” Science, Quantity 353, Aug. 12, 2016. https://www.science.org/doi/abs/10.1126/science.aaf1703
- St. Lawrence Shark Observatory (ORS), “Meet the world’s oldest-living vertebrate, the Greenland Shark,” 2019. https://geerg.ca/en/greenland-shark/