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Greenland shark

January 31, 2023

The Greenland shark (Somniosus microcephalus), also known as the gurry shark, grey shark, or by the Kalaallisut name eqalussuaq, is a large shark of the family Somniosidae ("sleeper sharks"), closely related to the Pacific and southern sleeper sharks.[2] The distribution of this species is mostly restricted to the waters of the North Atlantic Ocean and Arctic Ocean; however, more recent evidence indicates that at great depths it may range as far south as the Caribbean.

Greenland shark
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Superorder: Selachimorpha
Order: Squaliformes
Family: Somniosidae
Genus: Somniosus
Species:
S. microcephalus
Binomial name
Somniosus microcephalus
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 has the longest known lifespan of all vertebrate species (estimated to be between 250 and 500 years),[3] and is among the largest extant species of shark. It is a generalist feeder, consuming a variety of available foods.[4] As an adaptation to living at depth,[5] it has a high concentration of trimethylamine N-oxide in its tissues, which causes the meat to be toxic.[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 one of the largest living species of shark. It usually grows between 2.4–4.3 m (7.9–14.1 ft) long and weighs between 700–1,000 kg (1,500–2,200 lb),[8][9] but has been recorded at up to 7.3 m (24 ft) and more than 1,400 kg (3,100 lb).[10][11] Other sources observe most Greenland sharks at around 2.4–4.8 m (8–16 ft) long and weighing up to 400 kg (880 lb).[10][11]

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]

Dentition

 
The dentition of a Greenland shark

When feeding on large carcasses, the shark employs a rolling motion of its jaw. The 48–52 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 48–52 lower teeth are interlocking and are broad and square, containing short, smooth cusps that point outward.[10] Teeth in the two halves of the lower jaw are strongly pitched in opposite directions.[12]

Behaviour

Diet

The Greenland shark is an apex predator and mostly eats fish, and has 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.[13] 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.[14]

Greenland sharks, because of their slow speeds, often hunt prey that are asleep. Using their cryptic coloration, they can approach prey undetected before closing the remaining distance by opening their large buccal cavity in order to create a suction that draws in the prey. This is the likely explanation as to why the gut contents discovered in Greenland sharks is often whole prey specimens.[13]

Greenland sharks have also been found with remains of seals, polar bears, moose,[15] and reindeer (in one case an entire reindeer body) in their stomachs.[10][16] 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.[17]

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

As an ectotherm living in a just-above-freezing environment, the Greenland shark has 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.[18] It swims at 1.22 km/h (0.76 mph), with its fastest cruising speed only reaching 2.6 km/h (1.6 mph).[19] 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.[20]

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 300 km (160 nmi) east of Cape Hatteras, North Carolina.[21] Daily vertical migration between shallower and deeper waters has also been recorded.[22]

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).[23] Four previous records of Greenland shark were reported from Cuba and the northern Gulf of Mexico.[24] 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.[25][26]

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.[27]

Other behaviours

The shark is often infested by the copepod Ommatokoita elongata, a crustacean which attaches itself to the shark's eyes.[28] 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.[29] These parasites also damage the eyeball in a number of 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.[28][30] 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]

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)[31]

Longevity

The Greenland shark has the longest known lifespan of all vertebrate species.[32] 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.[33] 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.[a] The authors further concluded that the species reaches sexual maturity at about 150 years of age.[32][34][35] Efforts to conserve Greenland sharks are particularly important due to their extreme longevity, long maturation periods, and the heightened sensitivity of large shark populations.[36]

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.[18] About ten pups per litter is normal, each initially measuring some 38–42 cm (15–16+1⁄2 in) in length.[34][37][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.[38] It has been estimated that due to their extreme longevity, Greenland sharks can have 200 to 700 pups during their lifetime.[18]

Physiological adaptations

 
Greenland shark at Admiralty Inlet, Nunavut, with an Ommatokoita

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[39] and function as osmoprotectants. TMAO also counteracts the protein-destabilizing tendencies of urea[40][41] and of deep-water pressure.[5][41] Its presence in the tissues of both elasmobranch and teleost fish has been found to increase with depth.[5][42]

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 elasmobranch physiology. They display identical electronic absorption and resonance Raman spectra, indicating that their heme-pocket structures are identical or highly similar. The hemoglobins also have a lower affinity for O2 compared to temperate sharks. These characteristics are interpreted as adaptations to living at great water depths.[43]

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.[44][45]

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 dug up and hung up in strips to dry for several more months.[46] It is considered a delicacy in Iceland.[47][self-published source?][48][49]

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.[50] 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.[51] Another legend tells of Sedna whose father cut off her fingers while drowning her, with each finger turning into a sea creature, including Skalugsuak.[52]

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.[53]

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.[13][14]

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.[54]

Threats

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

The shark has historically been targeted 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.[55][full citation needed] In the 1970s, the species was perceived as a problem for other fisheries in western Norway and the government subsidized a fishery in order to reduce the stock of the species.[56][full citation needed] Approximately 3,500 individuals are taken as bycatch each year in the Atlantic and Arctic Ocean and Barents Sea.[57][full citation needed] More than 1,000 individuals are caught annually from Arctic waters south to USA waters.[58][full citation needed] Annual catch of Greenland shark from the Barents Sea was estimated to be around 1,200 individuals per year.[57][1]

The shark is also likely affected by anthropogenic climate change, which is affecting the quantity, dynamics, and distribution of Arctic sea ice.[54] 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.[54] Further, there is greater potential for new fisheries to develop as more productive and abundant southerly species invade the warming Arctic waters.[59][full citation needed][1]

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

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Further reading

  • MacNeil, M.A.; McMeans, B. C.; Hussey, N. E.; Vecsei, P.; Svavarsson, J.; Kovacs, K. M.; Lydersen, C.; Treble, M.A.; et al. (2012). "Biology of the Greenland shark Somniosus microcephalus". Journal of Fish Biology. 80 (5): 991–1018. doi:10.1111/j.1095-8649.2012.03257.x. PMID 22497371.
  • 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.
    • Jeanna Bryner (25 June 2012). "Sea's slowest sharks snack on sleeping seals". LiveScience.
  • Herbert, N.A.; Skov, P.V.; Tirsgaard, B.; Bushnell, P.G.; Brill, R.W.; Harvey Clark, C.; Steffensen, J.F. (2017). "Blood O2 affinity of a large polar elasmobranch, the Greenland shark Somniosus microcephalus". Polar Biology. 40 (11): 2297–2305. doi:10.1007/s00300-017-2142-z. S2CID 206954171.
  • Shadwick, R.E.; Bernal, D.; Bushnell, P.G.; Steffensen, J.F. (2018). "Blood pressure in the Greenland shark as estimated from ventral aortic elasticity". Journal of Experimental Biology. 221 (Pt 19). doi:10.1242/jeb.186957. PMID 30104302. S2CID 51976050.
  • Nielsen, J.; Schou Christiansen, J.; Grønkjær, P.; Bushnell, P.G.; Steffensen, J.F.; Overgaard Kiilerich, H.; et al. (2019). "Greenland shark (Somniosus microcephalus) stomach contents and stable isotope values reveal an ontogenetic dietary shift". Marine Megafauna. Frontiers in Marine Science. 6. doi:10.3389/fmars.2019.00125.
  • Nielsen, J.; Hedeholm, R.B.; Lynghammar, A.; McClusky, L.M.; Berland, B.; Steffensen, J.F.; Christiansen, J.S. (2020). "Assessing the reproductive biology of the Greenland shark (Somniosus microcephalus)". PLOS ONE. 15 (10): e0238986. Bibcode:2020PLoSO..1538986N. doi:10.1371/journal.pone.0238986. PMC 7540863. PMID 33027263.

External links

 
Wikimedia Commons has media related to Somniosus microcephalus.
 
Wikispecies has information related to Somniosus microcephalus.
  • Greenland Shark and Elasmobranch Education and Research Group
  • Canadian Museum of Nature SV Greenland Shark
  • "Somniosus microcephalus". Integrated Taxonomic Information System. Retrieved 23 January 2006.
  • Froese, Rainer; Pauly, Daniel (eds.) (2006). "Somniosus microcephalus" in FishBase. May 2006 version.
  • (WMV file)
  • Greenland shark – Video on Check123[permanent dead link]
  • Old and Cold: Biology of the Greenland shark - project at Univ Copenhagen - http://mbl.ku.dk/JFSteffensen/OldAndCold/
  • Old and Cold: Biology of the Greenland shark - project on ResearchGate [1]

January 31, 2023
greenland, shark, somniosus, microcephalus, also, known, gurry, shark, grey, shark, kalaallisut, name, eqalussuaq, large, shark, family, somniosidae, sleeper, sharks, closely, related, pacific, southern, sleeper, sharks, distribution, this, species, mostly, re. The Greenland shark Somniosus microcephalus also known as the gurry shark grey shark or by the Kalaallisut name eqalussuaq is a large shark of the family Somniosidae sleeper sharks closely related to the Pacific and southern sleeper sharks 2 The distribution of this species is mostly restricted to the waters of the North Atlantic Ocean and Arctic Ocean however more recent evidence indicates that at great depths it may range as far south as the Caribbean Greenland sharkConservation statusVulnerable IUCN 3 1 1 Scientific classificationKingdom AnimaliaPhylum ChordataClass ChondrichthyesSuperorder SelachimorphaOrder SqualiformesFamily SomniosidaeGenus SomniosusSpecies S microcephalusBinomial nameSomniosus microcephalus Bloch amp J G Schneider 1801 Range of the Greenland sharkSynonymsSqualus squatina non Linnaeus 1758 Squalus carcharis Gunnerus 1776 Squalus microcephalus Bloch amp 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 has the longest known lifespan of all vertebrate species estimated to be between 250 and 500 years 3 and is among the largest extant species of shark It is a generalist feeder consuming a variety of available foods 4 As an adaptation to living at depth 5 it has a high concentration of trimethylamine N oxide in its tissues which causes the meat to be toxic 6 Greenland shark flesh treated to reduce toxin levels is eaten in Iceland as a delicacy known as kaestur hakarl 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 Contents 1 Description 1 1 Dentition 2 Behaviour 2 1 Diet 2 2 Movement 2 3 Other behaviours 2 4 Longevity 2 5 Reproduction 3 Physiological adaptations 4 As food 5 Inuit legends 6 Ecological importance 6 1 Role in Arctic ecosystems 6 2 Conservation and management 7 Threats 8 See also 9 Notes 10 References 11 Further reading 12 External linksDescription EditThe Greenland shark is one of the largest living species of shark It usually grows between 2 4 4 3 m 7 9 14 1 ft long and weighs between 700 1 000 kg 1 500 2 200 lb 8 9 but has been recorded at up to 7 3 m 24 ft and more than 1 400 kg 3 100 lb 10 11 Other sources observe most Greenland sharks at around 2 4 4 8 m 8 16 ft long and weighing up to 400 kg 880 lb 10 11 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 Dentition Edit The dentition of a Greenland shark When feeding on large carcasses the shark employs a rolling motion of its jaw The 48 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 52 lower teeth are interlocking and are broad and square containing short smooth cusps that point outward 10 Teeth in the two halves of the lower jaw are strongly pitched in opposite directions 12 Behaviour EditDiet Edit The Greenland shark is an apex predator and mostly eats fish and has 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 13 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 14 Greenland sharks because of their slow speeds often hunt prey that are asleep Using their cryptic coloration they can approach prey undetected before closing the remaining distance by opening their large buccal cavity in order to create a suction that draws in the prey This is the likely explanation as to why the gut contents discovered in Greenland sharks is often whole prey specimens 13 Greenland sharks have also been found with remains of seals polar bears moose 15 and reindeer in one case an entire reindeer body in their stomachs 10 16 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 17 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 Edit As an ectotherm living in a just above freezing environment the Greenland shark has 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 18 It swims at 1 22 km h 0 76 mph with its fastest cruising speed only reaching 2 6 km h 1 6 mph 19 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 20 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 300 km 160 nmi east of Cape Hatteras North Carolina 21 Daily vertical migration between shallower and deeper waters has also been recorded 22 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 23 Four previous records of Greenland shark were reported from Cuba and the northern Gulf of Mexico 24 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 25 26 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 27 Other behaviours Edit The shark is often infested by the copepod Ommatokoita elongata a crustacean which attaches itself to the shark s eyes 28 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 29 These parasites also damage the eyeball in a number of 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 28 30 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 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 31 Longevity Edit The Greenland shark has the longest known lifespan of all vertebrate species 32 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 33 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 a The authors further concluded that the species reaches sexual maturity at about 150 years of age 32 34 35 Efforts to conserve Greenland sharks are particularly important due to their extreme longevity long maturation periods and the heightened sensitivity of large shark populations 36 Reproduction Edit 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 18 About ten pups per litter is normal each initially measuring some 38 42 cm 15 16 1 2 in in length 34 37 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 38 It has been estimated that due to their extreme longevity Greenland sharks can have 200 to 700 pups during their lifetime 18 Physiological adaptations Edit Greenland shark at Admiralty Inlet Nunavut with an Ommatokoita 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 39 and function as osmoprotectants TMAO also counteracts the protein destabilizing tendencies of urea 40 41 and of deep water pressure 5 41 Its presence in the tissues of both elasmobranch and teleost fish has been found to increase with depth 5 42 The blood of Greenland sharks contains three major types of hemoglobin made up of two copies of a globin combined with two copies of three very similar b subunits These three types show very similar oxygenation and carbonylation properties which are unaffected by urea an important compound in marine elasmobranch physiology They display identical electronic absorption and resonance Raman spectra indicating that their heme pocket structures are identical or highly similar The hemoglobins also have a lower affinity for O2 compared to temperate sharks These characteristics are interpreted as adaptations to living at great water depths 43 As food Edit Greenland shark meat or kaestur hakarl 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 44 45 The meat can be treated for safe consumption by boiling in several changes of water drying or fermenting for several months to produce kaestur hakarl 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 dug up and hung up in strips to dry for several more months 46 It is considered a delicacy in Iceland 47 self published source 48 49 Inuit legends EditThe Greenland shark s poisonous flesh has a high urea content which gave rise to the Inuit legend of Skalugsuak the first Greenland shark 50 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 51 Another legend tells of Sedna whose father cut off her fingers while drowning her with each finger turning into a sea creature including Skalugsuak 52 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 53 Ecological importance EditRole in Arctic ecosystems Edit 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 13 14 Conservation and management Edit 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 54 Threats Edit Overfishing and climate change are the main driving factors of Greenland shark diminishing numbers The shark has historically been targeted 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 55 full citation needed In the 1970s the species was perceived as a problem for other fisheries in western Norway and the government subsidized a fishery in order to reduce the stock of the species 56 full citation needed Approximately 3 500 individuals are taken as bycatch each year in the Atlantic and Arctic Ocean and Barents Sea 57 full citation needed More than 1 000 individuals are caught annually from Arctic waters south to USA waters 58 full citation needed Annual catch of Greenland shark from the Barents Sea was estimated to be around 1 200 individuals per year 57 1 The shark is also likely affected by anthropogenic climate change which is affecting the quantity dynamics and distribution of Arctic sea ice 54 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 54 Further there is greater potential for new fisheries to develop as more productive and abundant southerly species invade the warming Arctic waters 59 full citation needed 1 See also Edit Sharks portalPacific sleeper shark Southern sleeper shark List of sharksNotes Edit Lower age estimage 392 120 272 years and 2016 272 1744 higher age estimate 392 120 512 years and 2016 512 1504 References Edit a b c d 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 Retrieved 19 November 2021 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 S2CID 38054192 How long do Greenland sharks live National Ocean Service Retrieved 2 June 2021 a b Nielsen Julius Hedeholm Rasmus B Simon Malene Steffensen John F 1 January 2014 Distribution and feeding ecology of the Greenland shark Somniosus microcephalus in Greenland waters Polar Biology 37 1 37 46 doi 10 1007 s00300 013 1408 3 ISSN 1432 2056 S2CID 17829168 a b c 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 Bibcode 2014PNAS 111 4461Y doi 10 1073 pnas 1322003111 PMC 3970477 PMID 24591588 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 Durst Sidra 2012 Hakarl In Deutsch Jonathan Murakhver Natalya eds They Eat That A cultural encyclopedia of weird and exotic food from around the world pp 91 92 ISBN 978 0 313 38059 4 Mills Patrick 2006 Dewey Tanya ed Somniosus microcephalus Animal Diversity Web University of Michigan 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 PMC 4304853 PMID 25649000 a b c d e f g h Eagle Dane Greenland shark Florida Museum of Natural History Archived from the original on 21 March 2013 Retrieved 26 June 2012 a b Wood Gerald 1983 The Guinness Book of Animal Facts and Feats ISBN 978 0 85112 235 9 page needed Greenland Shark Marinebiodiversity ca Centre for Marine Biodiversity Archived from the original on 3 April 2014 Retrieved 23 May 2011 a b c Lydersen Christian Fisk Aaron T Kovacs Kit M November 2016 A review of Greenland shark Somniosus microcephalus studies in the Kongsfjorden area Svalbard Norway Polar Biology 39 11 2169 2178 doi 10 1007 s00300 016 1949 3 ISSN 0722 4060 S2CID 15050012 a b Nielsen Julius Christiansen Jorgen Schou Gronkjaer 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 Frontiers in Marine Science 6 doi 10 3389 fmars 2019 00125 ISSN 2296 7745 Moose eating shark rescued in Newfoundland harbour CBC News 21 November 2013 Retrieved 21 November 2013 Howden Daniel 12 August 2008 Clash of the fiercest predators as shark eats polar bear The Independent Retrieved 26 June 2012 Yong Ed 11 August 2016 The sharks that live to 400 The Atlantic Retrieved 15 August 2016 a b c Augustine Starrlight Lika Konstadia Kooijman Sebastiaan A L M 1 December 2017 Comment on the ecophysiology of the Greenland shark Somniosus microcephalus PDF Polar Biology 40 12 2429 2433 doi 10 1007 s00300 017 2154 8 hdl 1871 1 a6f1d885 5cd1 431f 8e85 540060915b6c ISSN 1432 2056 S2CID 20852421 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 Scales Helen June 2012 Slow sharks sneak up on sleeping seals and eat them National Geographic News Retrieved 28 December 2012 America s lost treasure sscentralamerica com Archived from the original on 24 November 2016 Retrieved 14 February 2017 Owen D 2009 Shark In peril in the sea Allen amp Unwin Grubs Dean 15 August 2013 Deep C Scientists Capture First Greenland Shark in the Gulf of Mexico deep c org 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 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 Moller P R Nielsen J Knudsen S W Poulsen J Y Sunksen K Jorgensen O A 2010 A checklist of the fish fauna of Greenland waters Zootaxa 2378 1 1 84 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 S2CID 250590599 Retrieved 30 July 2022 a b 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 amp Schneider Journal of Fish Diseases 21 6 415 422 doi 10 1046 j 1365 2761 1998 00122 x Berland Bjorn 1961 Copepod Ommatokoita elongata Grant in the eyes of the Greenland shark a possible cause of mutual dependence Nature 191 4790 829 830 Bibcode 1961Natur 191 829B doi 10 1038 191829a0 S2CID 4262630 Ferrando S Gallus L Ghigliotti L Vacchi M Nielsen J Christiansen J S Pisano E 1 August 2016 Gross morphology and histology of the olfactory organ of the Greenland shark Somniosus microcephalus Polar Biology 39 8 1399 1409 doi 10 1007 s00300 015 1862 1 ISSN 1432 2056 S2CID 17368573 Dewhurst H W 1834 The Natural History of the Order Cetacea and the Oceanic Inhabitants of the Arctic Regions Verf Illustrated with numerous lithographic and wood engravings a b Nielsen Julius Hedeholm Rasmus B Heinemeier Jan Bushnell Peter G Christiansen Jorgen S Olsen Jesper et al 2016 Eye lens radiocarbon reveals centuries of longevity in the Greenland shark Somniosus microcephalus Science 353 6300 702 704 Bibcode 2016Sci 353 702N doi 10 1126 science aaf1703 hdl 2022 26597 PMID 27516602 S2CID 206647043 de Lazaro Enrico 12 August 2016 Greenland sharks are longest lived vertebrates on Earth marine biologists say Science News Caloyianis Nick September 1998 Greenland Sharks National Geographic 194 3 60 71 a b Pennisi Elizabeth 11 August 2016 Greenland shark may live 400 years smashing longevity record Science doi 10 1126 science aag0748 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 Retrieved 27 November 2017 Davis Brendal van der Zwaag David L Cosandey Godin Aurelie Hussey Nigel E Kessel Steven T Worm Boris 1 October 2013 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 amp Policy 16 4 300 330 doi 10 1080 13880292 2013 805073 ISSN 1388 0292 S2CID 84039070 Martin R Aidan Greenland shark elasmo research org Retrieved 23 May 2011 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 S2CID 221121663 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 JSTOR 30163765 S2CID 100989392 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 Bibcode 2004PNAS 101 6433B doi 10 1073 pnas 0308633101 PMC 404062 PMID 15096583 a b 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 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 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 Bibcode 2017PLoSO 1286181R doi 10 1371 journal pone 0186181 PMC 5638460 PMID 29023598 The Greenland shark is a very odd species of shark Shark Sider December 2014 Retrieved 17 August 2016 The Greenland shark An icy mystery Sharkopedia Discovery com Archived from the original on 7 January 2018 Retrieved 17 August 2016 Wheatley Gale 20 September 2010 Iceland s wild culinary traditions Hakarl and brennivin gourmetwonderland com Archived from the original on 6 March 2014 Retrieved 12 August 2016 Blumenfeld Jenna 16 June 2011 My encounter with hakarl the worst tasting food on Earth theexpeditioner com Hakarl Icelandic fermented shark Islands Retrieved 13 August 2016 permanent dead link 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 Insider Retrieved 23 January 2022 O Reilly Lindsay 2004 Skalugsuak s origins Canadian Geographic Archived from the original on 21 March 2016 Retrieved 13 August 2016 Greenland shark Greenland Shark and Elasmobranch Education and Research Group Archived from the original on 14 October 2013 Retrieved 13 August 2016 Helfman Gene Burgess George H 2014 Sharks The animal answer guide Johns Hopkins University Press Idrobo Carlos Julian February 2009 The Pangnirtung Inuit and the Greenland Shark PDF M Sc thesis University of Manitoba p 66 OCLC 855389661 a b c Edwards Jena E Hiltz Elizabeth Broell Franziska Bushnell Peter G Campana Steven E Christiansen Jorgen S et al 2 April 2019 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 Hedeholm et al 2018 Castro et al 1999 a b Rusyaev and Orlov 2013 Bryk et al 2018 full citation needed Hedeholm et al 2018 full citation needed Hendrickson 2018 full citation needed Hendrickson et al 2018 full citation needed Simpson et al 2018 full citation needed Wheeland and Devine 2018 full citation needed Tai et al 2019Further reading EditMacNeil M A McMeans B C Hussey N E Vecsei P Svavarsson J Kovacs K M Lydersen C Treble M A et al 2012 Biology of the Greenland shark Somniosus microcephalus Journal of Fish Biology 80 5 991 1018 doi 10 1111 j 1095 8649 2012 03257 x PMID 22497371 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 Jeanna Bryner 25 June 2012 Sea s slowest sharks snack on sleeping seals LiveScience Herbert N A Skov P V Tirsgaard B Bushnell P G Brill R W Harvey Clark C Steffensen J F 2017 Blood O2 affinity of a large polar elasmobranch the Greenland shark Somniosus microcephalus Polar Biology 40 11 2297 2305 doi 10 1007 s00300 017 2142 z S2CID 206954171 Shadwick R E Bernal D Bushnell P G Steffensen J F 2018 Blood pressure in the Greenland shark as estimated from ventral aortic elasticity Journal of Experimental Biology 221 Pt 19 doi 10 1242 jeb 186957 PMID 30104302 S2CID 51976050 Nielsen J Schou Christiansen J Gronkjaer P Bushnell P G Steffensen J F Overgaard Kiilerich H et al 2019 Greenland shark Somniosus microcephalus stomach contents and stable isotope values reveal an ontogenetic dietary shift Marine Megafauna Frontiers in Marine Science 6 doi 10 3389 fmars 2019 00125 Nielsen J Hedeholm R B Lynghammar A McClusky L M Berland B Steffensen J F Christiansen J S 2020 Assessing the reproductive biology of the Greenland shark Somniosus microcephalus PLOS ONE 15 10 e0238986 Bibcode 2020PLoSO 1538986N doi 10 1371 journal pone 0238986 PMC 7540863 PMID 33027263 External links Edit Wikimedia Commons has media related to Somniosus microcephalus Wikispecies has information related to Somniosus microcephalus Greenland Shark and Elasmobranch Education and Research Group Canadian Museum of Nature SV Greenland Shark Somniosus microcephalus Integrated Taxonomic Information System Retrieved 23 January 2006 Froese Rainer Pauly Daniel eds 2006 Somniosus microcephalus in FishBase May 2006 version Greenland Shark on As It Happens 6 May 2008 CBC Radio 1 WMV file Greenland shark Video on Check123 permanent dead link Old and Cold Biology of the Greenland shark project at Univ Copenhagen http mbl ku dk JFSteffensen OldAndCold Old and Cold Biology of the Greenland shark project on ResearchGate 1 Retrieved from https en wikipedia org w index php title Greenland shark amp oldid 1136591643, wikipedia, wiki, book, books, library,

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