Biology:Greenland shark

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Short description: Species of shark

Greenland shark
Somniosus microcephalus okeanos.jpg
Scientific classification edit
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Squaliformes
Family: Somniosidae
Genus: Somniosus
Species:
S. microcephalus
Binomial name
Somniosus microcephalus
(Bloch & J. G. Schneider, 1801)
Somniosus microcephalus distmap.png
Range of the Greenland shark
Synonyms
  • Squalus squatina (non Linnaeus, 1758)
  • Squalus carcharis (Gunnerus, 1776)
  • Squalus microcephalus Bloch & Schneider, 1801
  • Somniosus brevipinna (Lesueur, 1818)
  • Squalus borealis (Scoresby, 1820)
  • Squalus norvegianus (Blainville, 1825)
  • Scymnus gunneri (Thienemann, 1828)
  • Scymnus glacialis (Faber, 1829)
  • Scymnus micropterus (Valenciennes, 1832)
  • Leiodon echinatum (Wood, 1846)

The Greenland shark (Somniosus microcephalus), also known as the gurry shark or grey shark, is a large shark of the family Somniosidae ("sleeper sharks"), closely related to the Pacific and southern sleeper sharks.[2] The Greenland shark is a potentially important yet poorly studied cold-water species inhabiting the North Atlantic and Arctic Oceans.

The Greenland shark has the longest known lifespan of all vertebrate species estimated to be between 250 and 500 years;[3] it is among the largest extant species of shark. It reaches sexual maturity at about 150 years of age and pups are born alive after an estimated gestation period of 8–18 years. It is a generalist feeder, consuming a variety of available foods.[4] As an adaptation to living at depth,[5] it has 3 kinds of hemoglobin and a high concentration of trimethylamine N-oxide in its tissues to increase buoyancy. This causes the meat to be toxic to mammals.[6] Greenland shark flesh, treated to reduce toxin levels, is eaten in Iceland as a delicacy known as kæstur hákarl.[7] As it lives in the cold depths of the Arctic and North Atlantic, isolated from human activity, it is not known to be a threat to humans, and no attacks have been recorded.

Description

The Greenland shark is likely one of the largest living species of shark. It usually grows to between 2.4 and 7 m (7.9 and 23.0 ft) long and weighs between 400 and 1,400 kg (880 and 3,090 lb).[8][9][10][11] The all-tackle International Game Fish Association (IGFA) record for this species is 775 kg (1,709 lb).[12]

Greenland shark at Admiralty Inlet, Nunavut, with an Ommatokoita

Males are typically smaller than females. It rivals the Pacific sleeper shark (possibly up to 7 m or 23 ft long) as the largest species in the family Somniosidae. The Greenland shark is a thickset species, with a short, rounded snout, small eyes, and very small dorsal and pectoral fins. The gill openings are very small for the species' great size.

Coloration can range from pale creamy-gray to blackish-brown and the body is typically uniform in color, though whitish spots or faint dark streaks are occasionally seen on the back.[10]

The shark is often infested by the copepod Ommatokoita elongata, a crustacean which attaches itself to the shark's eyes.[13] It was speculated that the copepod may display bioluminescence and thus attract prey for the shark in a mutualistic relationship, but this hypothesis has not been verified.[14] These parasites also damage the eyeball in several ways, leading to almost complete blindness. This does not seem to reduce the life expectancy or predatory ability of Greenland sharks, due to their strong reliance on smell and hearing.[13][15]

Dentition

The dentition of a Greenland shark

When feeding on large carcasses, the shark employs a rolling motion of its jaw. The 48 to 52 teeth of the upper jaw are very thin and pointed, lacking serrations. These upper jaw teeth act as an anchor while the lower jaw proceeds to cut massive chunks out of the prey.

The 48 to 52 lower teeth are interlocking, broad and square in shape, containing short, smooth cusps that point outward.[10] Teeth in the two halves of the lower jaw are strongly pitched in opposite directions.[16]

Behavior

Diet

The Greenland shark is an apex predator and eats primarily fish, although they have been observed actively hunting seals in Canada.[4] The prey found in the stomachs of Greenland sharks is an indicator of the active hunting patterns of these predators.[17] Recorded fish prey have included smaller sharks, skates, eels, herring, capelin, Arctic char, cod, rosefish, sculpins, lumpfish, wolffish, and flounder.[10] Small Greenland sharks eat predominantly squid, while the larger sharks that are greater than 200 cm (79 in) were discovered eating prey such as epibenthic and benthic fishes as well as seals. The largest of these sharks were found having eaten redfish, as well as other higher trophic level prey.[18]

It is proposed, that because of their slow speeds and low twitch speed muscle fiber, Greenland sharks hunt marine mammals such as seals and smaller cetaceans that are asleep, injured, or sick. Regarding most other benthic species, they utilize their cryptic coloration, and approach prey undetected before closing the remaining distance, expanding their buccal cavity to create suction, drawing in prey. This is the likely explanation for why the gut contents of Greenland sharks are often whole prey specimens.[17]

Greenland sharks have also been found with remains of moose[19] and reindeer (in one case an entire reindeer body) in their stomachs.[10][20] The Greenland shark is known to be a scavenger and is attracted by the smell of rotting meat in the water. The sharks have frequently been observed gathering around fishing boats.[10] They also scavenge on seals.[21]

Although such a large shark could easily consume a human swimmer, the frigid waters it typically inhabits make the likelihood of attacks on people very low. No cases of predation on humans have been verified.[10]

Movement and migration

The shark occupies what tends to be a very deep environment seeking its preferred cold water (−0.6 to 12 °C or 31 to 54 °F) habitat.[1] As an ectotherm living in a just-above-freezing environment, the Greenland shark is sluggish and slow-moving, with the lowest swim speed and tail-beat frequency for its size across all fish species, which most likely correlates with its very slow metabolism and extreme longevity.[22] It swims at 1.22 km/h (0.76 mph), with its fastest cruising speed only reaching 2.6 km/h (1.6 mph).[23] Because this top speed is a fraction of that of a typical seal in their diet, biologists are uncertain how the sharks are able to prey on the seals. It is hypothesized that they may ambush them while they sleep.[24]

Greenland sharks migrate annually based on depth and temperature rather than distance, although some do travel. During the winter, the sharks congregate in the shallows (up to 80° north) for warmth but migrate separately in summer to the deeps or even farther south. The species has been observed at a depth of 2,200 metres (7,200 ft) by a submersible investigating the wreck of the SS Central America that lies about 160 nautical miles (180 mi; 300 km) east of Cape Hatteras, North Carolina.[25] Daily vertical migration between shallower and deeper waters has also been recorded.[26]

In August 2013, researchers from Florida State University caught a Greenland shark in the Gulf of Mexico at a depth of 1,749 m (5,738 ft), where the water temperature was 4.1 °C (39.4 °F).[27] Four previous records of Greenland shark were reported from Cuba and the northern Gulf of Mexico.[28] A more typical depth range is 0–1,500 m (0–4,900 ft), with the species often occurring in relatively shallow waters in the far north and deeper in the southern part of its range.[29][30]

In April 2022, a large Somniosus shark was caught and subsequently released on Glover's Reef off the coast of Belize. This shark was identified as being either a Greenland shark or a Greenland/Pacific sleeper shark hybrid. This observation is notable for being the first possible record of a Greenland shark from the Western Caribbean, and being caught on a nearshore coral reef (the only other record of this species from the Caribbean was made from a deep-water habitat off the Caribbean coast of Colombia). The discovery indicates that Greenland sharks may have a wider distribution in the tropics, primarily at greater depths, than previously believed.[31]

When hoisted upon deck, it beats so violently with its tail, that it is dangerous to be near it, and the seamen generally dispatch it, without much loss of time. The pieces that are cut off exhibit a contraction of their muscular fibres for some time after life is extinct. It is, therefore, extremely difficult to kill, and unsafe to trust the hand within its mouth, even when the head is cut off. And, if we are to believe Crantz, this motion is to be observed three days after, if the part is trod on or struck.
—Henry William Dewhurst, The Natural History of the Order Cetacea (1834)[32]

Longevity

The Greenland shark has the longest known lifespan of all vertebrate species.[33] One Greenland shark was tagged off the coast of Greenland in 1936 and recaptured in 1952. Its measurements suggest that Greenland sharks grow at a rate of 0.5–1 cm (1⁄4–1⁄2 in) per year.[34] In 2016, a study based on 28 specimens that ranged from 81 to 502 cm (2 ft 8 in–16 ft 6 in) in length used radiocarbon dating of crystals within the lenses of their eyes to determine their approximate ages. The oldest of the animals sampled, which was also the largest, had lived for 392 ± 120 years, and was consequently born between 1504 and 1744.[lower-alpha 1] The authors further concluded that the species reaches sexual maturity at about 150 years of age.[33][35][36] Efforts to conserve Greenland sharks are particularly important due to their extreme longevity, long maturation periods, and the heightened sensitivity of large shark populations.[37]

Reproduction

As recently as 1957, females were found not to deposit eggs in the bottom mud, but retain the developing embryos within their bodies so they are born alive (a process known as ovoviviparity) after an estimated gestation period of 8–18 years.[22] About ten pups per litter is normal, each initially measuring some 38–42 cm (15–16 1⁄2 in) in length.[35][38][self-published source?] Within a Greenland shark's uterus, villi serve a key function in supplying oxygen to embryos. It is speculated that due to embryonic metabolism dealing with reproduction, this only allows for a limited litter size of around 10 pups.[39] It has been estimated that due to their extreme longevity, Greenland sharks can have 200 to 700 pups during their lifetime.[22]

Physiological adaptations

Like other elasmobranchii, Greenland sharks have high concentrations of the two nitrogenous compounds urea and trimethylamine N-oxide (TMAO) in their tissues, which increase their buoyancy[40] and function as osmoprotectants. TMAO also counteracts the protein-destabilizing tendencies of urea[41][42] and deep-water pressure.[5][42] Its presence in the tissues of both elasmobranch and teleost fish has been found to increase with depth.[5][43]

The blood of Greenland sharks contains three major types of hemoglobin, made up of two copies of α globin combined with two copies of three very similar β subunits. These three types show very similar oxygenation and carbonylation properties, which are unaffected by urea, an important compound in marine elasmobranchii physiology. They display identical electronic absorption and resonance in Raman spectroscopy, indicating that their heme-pocket structures are identical or highly similar. The hemoglobins also have a lower affinity for oxygen compared to temperate sharks. These characteristics are interpreted as adaptations to living at great water depths.[44]

As food

Greenland shark meat or kæstur hákarl in Iceland

The flesh of the Greenland shark is toxic because of the presence of high concentrations of trimethylamine oxide (TMAO). If the meat is eaten without pretreatment, the ingested TMAO is metabolized into trimethylamine, which may be a uremic toxin. Occasionally, sled dogs that eat the flesh are unable to stand up because of this effect. Similar toxic effects occur with the related Pacific sleeper shark, but not in most other shark species.[45][46]

The meat can be treated for safe consumption by boiling in several changes of water, drying, or fermenting for several months to produce kæstur hákarl. Traditionally, this is done by burying the meat in boreal ground for 6–8 weeks, which presses the TMAO out of the meat and also results in partial fermentation. The meat is then excavated and hung in strips to dry for several more months.[47] It is considered a delicacy in Iceland.[48][self-published source?][49][50]

Inuit legends

The Greenland shark's poisonous flesh has a high urea content, which gave rise to the Inuit legend of Skalugsuak, the first Greenland shark.[51] The legend says that an old woman washed her hair in urine (a common practice to kill head lice) and dried it with a cloth. The cloth blew into the ocean to become Skalugsuak.[52] Another legend tells of Sedna whose father cut off her fingers while drowning her, with each finger turning into a sea creature, including Skalugsuak.[53]

The Greenland shark plays a role in cosmologies of the Inuit from the Canadian Eastern Arctic and Greenland. Igloolik Inuit believe that the shark lives within the urine pot of Sedna, goddess of the sea, and consequently, its flesh has a urine-like smell and acts as a helping spirit to shamans.[54]

Ecological importance

Role in Arctic ecosystems

As both scavengers and active predators, Greenland sharks have established themselves as apex predators in Arctic ecosystems. They eat a wide variety of fish, seals, and other prey within these ecosystems and have an important role in the intricate food web.[17][18]

Conservation and management

Greenland sharks are recognized as the longest-lived vertebrates on earth. They have a slow growth rate, late maturity period, and low fecundity, making the management and conservation of this species very important. As a result of their low productivity and extreme longevity, this species is particularly susceptible to overfishing. Therefore, Greenland sharks' longevity and conservative life history traits, in tandem with their vulnerability to accidental catching and commercial fishing, promotes a growing concern for the sustainability of this species.[55]

Threats

Overfishing and climate change are the main driving factors of Greenland shark diminishing numbers

The shark has historically been hunted for its liver oil up until the development of synthetic oils and cessation of export of liver oil and skin from Greenland in the 1960s.[56] In the 1970s, the species was perceived as a problem for other fisheries in western Norway and the government subsidized a fishery to reduce the stock of the species.[57]

Approximately 3,500 individuals are taken each year in the Northwest Atlantic. Of this number, 89% comes from the Barents Sea, Iceland, Greenland, and the Canadian Arctic.[1]

The shark is likely affected by quantity, dynamics, and distribution of Arctic sea ice.[55] The rate of projected loss of sea ice will continue to negatively influence the abundance, distribution and availability of prey, while, at the same time, providing greater access for fishing fleets.[55] There is greater potential for new fisheries to develop as more productive and abundant southerly species invade the warming Arctic waters.[58]

See also

Notes

  1. ↑ Lower-age estimage 392 − 120 = 272 years, and 2016 − 272 = 1744; higher age estimate 392 + 120 = 512 years, and 2016 − 512 = 1504.

References

  1. ↑ 1.0 1.1 1.2 Kulka, D.W.; Cotton, C.F.; Anderson, B.; Derrick, D.; Herman, K.; Dulvy, N.K. (2020). "Somniosus microcephalus". IUCN Red List of Threatened Species 2020: e.T60213A124452872. doi:10.2305/IUCN.UK.2020-3.RLTS.T60213A124452872.en. https://www.iucnredlist.org/species/60213/124452872. Retrieved 19 November 2021. 
  2. ↑ Yano, Kazunari; Stevens, John D.; Compagno, Leonard J.V. (2004). "A review of the systematics of the sleeper shark genus Somniosus with redescriptions of Somniosus (Somniosus) antarcticus and Somniosus (Rhinoscymnus) longus (Squaliformes: Somniosidae)". Ichthyological Research 51 (4): 360–373. doi:10.1007/s10228-004-0244-4. 
  3. ↑ "How long do Greenland sharks live?". https://oceanservice.noaa.gov/facts/greenland-shark.html. 
  4. ↑ 4.0 4.1 Nielsen, Julius; Hedeholm, Rasmus B.; Simon, Malene; Steffensen, John F. (2014-01-01). "Distribution and feeding ecology of the Greenland shark (Somniosus microcephalus) in Greenland waters" (in en). Polar Biology 37 (1): 37–46. doi:10.1007/s00300-013-1408-3. ISSN 1432-2056. 
  5. ↑ 5.0 5.1 5.2 Yancey, Paul H.; Gerringer, Mackenzie E.; Drazen, Jeffrey C.; Rowden, Ashley A.; Jamieson, Alan (2014). "Marine fish may be biochemically constrained from inhabiting the deepest ocean depths". Proceedings of the National Academy of Sciences of the United States of America 111 (12): 4461–4465. doi:10.1073/pnas.1322003111. PMID 24591588. Bibcode: 2014PNAS..111.4461Y. 
  6. ↑ Anthoni, Uffe; Christophersen, Carsten; Gram, Lone; Nielsen, Niels H.; Nielsen, Per (1991). "Poisonings from flesh of the Greenland shark Somniosus microcephalus may be due to trimethylamine". Toxicon 29 (10): 1205–1212. doi:10.1016/0041-0101(91)90193-U. PMID 1801314. 
  7. ↑ Durst, Sidra (2012). "Hákarl". in Deutsch, Jonathan; Murakhver, Natalya. They Eat That? A cultural encyclopedia of weird and exotic food from around the world. Bloomsbury Publishing USA. pp. 91–92. ISBN 978-0-313-38059-4. https://books.google.com/books?id=H6pIinfPtnQC&pg=PA91. 
  8. ↑ Mills, Patrick (2006). "Somniosus microcephalus". in Dewey, Tanya. University of Michigan. http://animaldiversity.ummz.umich.edu/site/accounts/information/Somniosus_microcephalus.html. 
  9. ↑ McClain, Craig R.; Balk, Meghan A.; Benfield, Mark C.; Branch, Trevor A.; Chen, Catherine; Cosgrove, James et al. (13 January 2015). "Sizing ocean giants: patterns of intraspecific size variation in marine megafauna". PeerJ 3: e715. doi:10.7717/peerj.715. PMID 25649000. 
  10. ↑ 10.0 10.1 10.2 10.3 10.4 10.5 10.6 Eagle, Dane. "Greenland shark". Florida Museum of Natural History. http://www.flmnh.ufl.edu/fish/Gallery/Descript/GreenlandShark/GreenlandShark.html. 
  11. ↑ Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. Guinness Superlatives. ISBN 978-0-85112-235-9. https://archive.org/details/guinnessbookofan00wood. [page needed]
  12. ↑ "IGFA Member Services". https://igfa.org/member-services/world-record/common-name/Shark,%20Greenland. 
  13. ↑ 13.0 13.1 Borucinska, J.D.; Benz, G.W.; Whiteley, H.E. (1998). "Ocular lesions associated with attachment of the parasitic copepod Ommatokoita elongata (Grant) to corneas of Greenland sharks, Somniosus microcephalus (Bloch & Schneider)". Journal of Fish Diseases 21 (6): 415–422. doi:10.1046/j.1365-2761.1998.00122.x. 
  14. ↑ Berland, Bjørn (1961). "Copepod Ommatokoita elongata (Grant) in the eyes of the Greenland shark – a possible cause of mutual dependence". Nature 191 (4790): 829–830. doi:10.1038/191829a0. Bibcode: 1961Natur.191..829B. 
  15. ↑ Ferrando, S.; Gallus, L.; Ghigliotti, L.; Vacchi, M.; Nielsen, J.; Christiansen, J.S.; Pisano, E. (2016-08-01). "Gross morphology and histology of the olfactory organ of the Greenland shark Somniosus microcephalus" (in en). Polar Biology 39 (8): 1399–1409. doi:10.1007/s00300-015-1862-1. ISSN 1432-2056. 
  16. ↑ "Greenland Shark". Centre for Marine Biodiversity. http://www.marinebiodiversity.ca/shark/english/greenland.htm. 
  17. ↑ 17.0 17.1 17.2 Lydersen, Christian; Fisk, Aaron T.; Kovacs, Kit M. (November 2016). "A review of Greenland shark (Somniosus microcephalus) studies in the Kongsfjorden area, Svalbard Norway" (in en). Polar Biology 39 (11): 2169–2178. doi:10.1007/s00300-016-1949-3. ISSN 0722-4060. http://link.springer.com/10.1007/s00300-016-1949-3. 
  18. ↑ 18.0 18.1 Nielsen, Julius; Christiansen, Jørgen Schou; Grønkjær, Peter; Bushnell, Peter; Steffensen, John Fleng; Kiilerich, Helene Overgaard et al. (2019). "Greenland shark (Somniosus microcephalus) stomach contents and stable isotope values reveal an ontogenetic dietary shift" (in en). Frontiers in Marine Science 6. doi:10.3389/fmars.2019.00125. ISSN 2296-7745. 
  19. ↑ "Moose-eating shark rescued in Newfoundland harbour". CBC News. 21 November 2013. http://www.cbc.ca/news/canada/newfoundland-labrador/moose-eating-shark-rescued-in-newfoundland-harbour-1.2434102. 
  20. ↑ Howden, Daniel (12 August 2008). "Clash of the fiercest predators as shark eats polar bear". The Independent. https://www.independent.co.uk/environment/nature/clash-of-the-fiercest-predators-as-shark-eats-polar-bear-891512.html. 
  21. ↑ Yong, Ed (11 August 2016). "The sharks that live to 400". The Atlantic. https://www.theatlantic.com/science/archive/2016/08/these-sharks-live-to-400/495425/. 
  22. ↑ 22.0 22.1 22.2 Augustine, Starrlight; Lika, Konstadia; Kooijman, Sebastiaan A.L.M. (2017-12-01). "Comment on the ecophysiology of the Greenland shark, Somniosus microcephalus" (in en). Polar Biology 40 (12): 2429–2433. doi:10.1007/s00300-017-2154-8. ISSN 1432-2056. https://research.vu.nl/ws/files/45742779/AuguLika2017.pdf. 
  23. ↑ Watanabe, Yuuki Y.; Lydersen, Christian; Fisk, Aaron T.; Kovacs, Kit 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. doi:10.1016/j.jembe.2012.04.021. http://id.nii.ac.jp/1291/00012870/. 
  24. ↑ Scales, Helen (June 2012). "Slow sharks sneak up on sleeping seals (and eat them)?". http://news.nationalgeographic.com/news/2012/06/120626-greenland-sharks-seals-sleeping-animals-science/. 
  25. ↑ "America's lost treasure". http://www.sscentralamerica.com/history.html. 
  26. ↑ Owen, D. (2009). Shark: In peril in the sea. Allen & Unwin. 
  27. ↑ Grubs, Dean (15 August 2013). " Deep-C Scientists Capture First Greenland Shark in the Gulf of Mexico". deep-c.org
  28. ↑ Benfield, Mark (2008). "The second report of a sleeper shark (Somniosus (Somniosus) sp.) from the bathypelagic waters of the northern Gulf of Mexico". Bulletin of Marine Science 82 (2): 195–198. https://www.ingentaconnect.com/contentone/umrsmas/bullmar/2008/00000082/00000002/art00003. 
  29. ↑ Yano, K.; Stevens, J.D.; Compagno, L.J.V. (2007). "Distribution, reproduction and feeding of the Greenland shark Somniosus (Somniosus) microcephalus, with notes on two other sleeper sharks, Somniosus (Somniosus) pacificus and Somniosus (Somniosus) antarcticus". Journal of Fish Biology 70 (2): 374–390. doi:10.1111/j.1095-8649.2007.01308.x. 
  30. ↑ Møller, P.R.; Nielsen, J.; Knudsen, S.W.; Poulsen, J.Y.; Sünksen, K.; Jørgensen, O.A. (2010). "A checklist of the fish fauna of Greenland waters". Zootaxa 2378 (1): 1–84. 
  31. ↑ Kasana, Devanshi; Martinez, Hector Daniel; Faux, Omar; Monzon, Neri; Guerra, Elio; Chapman, Demian D. (2022). "First report of a sleeper shark (Somniosus sp.) in the western Caribbean, off the insular slope of a coral atoll". Marine Biology 169 (8). doi:10.1007/s00227-022-04090-3. https://link.springer.com/epdf/10.1007/s00227-022-04090-3?sharing_token=VXiT5KW_ByL0LyWDhvA0Wfe4RwlQNchNByi7wbcMAY5gwh7ggHuDX17Xdv6hH6yKST6hxuBgXWPojH91Rx1N0XbgX8wYyl-5noIK73zByDvhU-j9etZLBY_N-NiAWg6xgCTD3hrY-ihVa7ptqfvpzs0aICODQ9VYpW2-ZDY0TXk=. Retrieved 2022-07-30. 
  32. ↑ Dewhurst, H.W. (1834). The Natural History of the Order Cetacea and the Oceanic Inhabitants of the Arctic Regions. Verf.. https://books.google.com/books?id=JpM-AAAAcAAJ. "Illustrated with numerous lithographic and wood engravings" 
  33. ↑ 33.0 33.1 Nielsen, Julius; Hedeholm, Rasmus B.; Heinemeier, Jan; Bushnell, Peter G.; Christiansen, Jørgen S.; Olsen, Jesper et al. (2016). "Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus)". Science 353 (6300): 702–704. doi:10.1126/science.aaf1703. PMID 27516602. Bibcode: 2016Sci...353..702N. https://ora.ox.ac.uk/objects/pubs:633506. 
    de Lazaro, Enrico (12 August 2016). "Greenland sharks are longest-lived vertebrates on Earth, marine biologists say". Science News. http://www.sci-news.com/biology/greenland-sharks-longest-lived-vertebrates-04099.html. 
  34. ↑ Caloyianis, Nick (September 1998). "Greenland Sharks". National Geographic 194 (3): 60–71. 
  35. ↑ 35.0 35.1 Pennisi, Elizabeth (11 August 2016). "Greenland shark may live 400 years, smashing longevity record". Science. doi:10.1126/science.aag0748. 
  36. ↑ O'Connor, M.R. (25 November 2017). "The strange and gruesome story of the Greenland shark, the longest-living vertebrate on Earth". The New Yorker. https://www.newyorker.com/tech/elements/the-strange-and-gruesome-story-of-the-greenland-shark-the-longest-living-vertebrate-on-earth. Retrieved 27 November 2017. 
  37. ↑ Davis, Brendal; van der Zwaag, David L.; Cosandey-Godin, Aurelie; Hussey, Nigel E.; Kessel, Steven T.; Worm, Boris (2013-10-01). "The conservation of the Greenland shark (Somniosus microcephalus): Setting scientific, law, and policy coordinates for avoiding a species at risk". Journal of International Wildlife Law & Policy 16 (4): 300–330. doi:10.1080/13880292.2013.805073. ISSN 1388-0292. 
  38. ↑ Martin, R. Aidan. "Greenland shark". http://www.elasmo-research.org/education/ecology/polar-greenland.htm. 
  39. ↑ Carter, Anthony M.; Soma, Hiroaki (1 August 2020). "Viviparity in the longest-living vertebrate, the Greenland shark (Somniosus microcephalus)". Placenta 97: 26–28. doi:10.1016/j.placenta.2020.05.014. PMID 32792058. 
  40. ↑ Withers, Philip C.; Morrison, Garrick; Guppy, Michael (1994). "Buoyancy Role of Urea and TMAO in an Elasmobranch Fish, the Port Jackson Shark, Heterodontus portusjacksoni". Physiological Zoology 67 (3): 693–705. doi:10.1086/physzool.67.3.30163765. 
  41. ↑ Bennion, Brian J.; Daggett, Valerie (2004). "Counteraction of urea-induced protein denaturation by trimethylamine N-oxide: a chemical chaperone at atomic resolution". Proceedings of the National Academy of Sciences of the United States of America 101 (17): 6433–6438. doi:10.1073/pnas.0308633101. PMID 15096583. Bibcode: 2004PNAS..101.6433B. 
  42. ↑ 42.0 42.1 Yancey, Paul H. (2005). "Organic osmolytes as compatible, metabolic and counteracting cytoprotectants in high osmolarity and other stresses". The Journal of Experimental Biology 208 (pt 15): 2819–2830. doi:10.1242/jeb.01730. PMID 16043587. 
  43. ↑ Treberg, Jason R.; Driedzic, William R. (2002). "Elevated levels of trimethylamine oxide in deep-sea fish: Evidence for synthesis and intertissue physiological importance". Journal of Experimental Zoology 293 (1): 39–45. doi:10.1002/jez.10109. PMID 12115917. 
  44. ↑ Russo, Roberta; Giordano, Daniela; Paredi, Gianluca; Marchesani, Francesco; Milazzo, Lisa; Altomonte, Giovanna et al. (12 October 2017). "The Greenland shark Somniosus microcephalus — hemoglobins and ligand-binding properties". PLOS ONE 12 (10): e0186181. doi:10.1371/journal.pone.0186181. PMID 29023598. Bibcode: 2017PLoSO..1286181R. 
  45. ↑ "The Greenland shark is a very odd species of shark" (in en-US). December 2014. http://www.sharksider.com/greenland-shark/. 
  46. ↑ "The Greenland shark: An icy mystery". http://sharkopedia.discovery.com/types-of-sharks/greenland-shark/. 
  47. ↑ Wheatley, Gale (20 September 2010). "Iceland's wild culinary traditions: Hákarl and brennivín". http://gourmetwonderland.com/hakarl-brennivin. 
  48. ↑ Blumenfeld, Jenna (16 June 2011). "My encounter with hákarl, the worst tasting food on Earth". http://www.theexpeditioner.com/2011/06/16/my-encounter-with-hakarl-the-worst-tasting-food-on-earth/. 
  49. ↑ "Hákarl – Icelandic fermented shark". http://www.islands.com/hakarl-icelandic-fermented-shark. [yes|permanent dead link|dead link}}]
  50. ↑ Shardlow, Ju; Romeo, Claudia. "Greenland shark is the most toxic shark in the world, but one family has been curing it for hundreds of years". https://www.insider.com/how-fermented-shark-is-made-bjarnarhoefn-iceland-2020-10. 
  51. ↑ O'Reilly, Lindsay (2004). "Skalugsuak's origins". http://www.canadiangeographic.ca/magazine/ma04/indepth/anthropology.asp. 
  52. ↑ "Greenland shark". Greenland Shark and Elasmobranch Education and Research Group. http://www.geerg.ca/gshark1.htm. 
  53. ↑ Helfman, Gene; Burgess, George H. (2014). Sharks: The animal answer guide. Johns Hopkins University Press. 
  54. ↑ Idrobo, Carlos Julián (February 2009). The Pangnirtung Inuit and the Greenland Shark (PDF) (M.Sc. thesis). University of Manitoba. p. 66. OCLC 855389661.
  55. ↑ 55.0 55.1 55.2 Edwards, Jena E.; Hiltz, Elizabeth; Broell, Franziska; Bushnell, Peter G.; Campana, Steven E.; Christiansen, Jørgen S. et al. (2019-04-02). "Advancing research for the management of long-lived species: A case study on the Greenland shark". Frontiers in Marine Science 6: 87. doi:10.3389/fmars.2019.00087. ISSN 2296-7745. 
  56. ↑ Hedeholm, R., Nygaard, R. and Nogueira, A. 2018. Greenland shark in Greenland waters in NAFO Subarea 1 and ICES XIV. North Atlantic Fisheries Organization Scientific Committee Report 18/037: 1-10.
  57. ↑ Castro, José I.; Woodley, Christa M.; Brudek, Rebecca L. (1999). "4. The status of elasmobranch species". A preliminary evaluation of the status of shark species. FAO fisheries technical paper. Rome: FAO. ISBN 978-92-5-104299-1. 
  58. ↑ Tai, Travis C.; Steiner, Nadja S.; Hoover, Carie; Cheung, William W.L.; Sumaila, U. Rashid (2019). "Evaluating present and future potential of arctic fisheries in Canada" (in en). Marine Policy 108: 103637. doi:10.1016/j.marpol.2019.103637. https://linkinghub.elsevier.com/retrieve/pii/S0308597X19300995. 

Further reading

External links

Wikidata ☰ Q370444 entry



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