قرش گرينلاند

قرش گرينلاند
Somniosus microcephalus okeanos.jpg
التصنيف العلمي
مملكة:
Phylum:
Class:
Order:
Family:
Genus:
Species:
S. microcephalus
Binomial name
Somniosus microcephalus
Somniosus microcephalus distmap.png
نطاق تواجد قرش گرينلاند
Synonyms
  • Squalus squatina (non لينايوس، 1758)
  • Squalus carcharis (گونروس، 1776)
  • Somniosus brevipinna (لسور، 1818)
  • Squalus borealis (سكورسبي، 1820)
  • Squalus norvegianus (بلين‌ڤيل، 1825)
  • Scymnus gunneri (تينـِمان، 1828)
  • Scymnus glacialis (فابر، 1829)
  • Scymnus micropterus (ڤالنسيان، 1832)
  • Leiodon echinatum (وود، 1846)

قرش گرينلاند (Greenland shark ؛ Somniosus microcephalus)، ويُعرف أيضاً بإسم gurry shark، أو القرش الرمادي، أو بإسمه بلغات الإنويت eqalussuaq إقالوسواق ، هو قرش كبير من فصيلة القروش النائمة Somniosidae، المرتبطة بوثوق بـقرش الهادي النائم والقرش النائم الجنوبي.[2] انتشار هذا النوع محصور غالباً في مياه شمال المحيط الأطلسي والمحيط القطبي.

وهو بين أكبر أنواع القرش المتواجدة، ويُعتبر الأطول عمراً بين كل الفقاريات على وجه الأرض، والعديد من التكيفات التشريحية والفسيولوجية هي بسبب موئله المتطرف. ومن تلك التكيفات التركزات العالية من ثلاثي مثيل‌أمين أكسيد نوني (TMAO) في لحمه، والذي يعمل كواقي من النضح وواقي من التجمد.[3] وجود هذه المادة الكيميائية يجعل لحم هذا القرش ساماً.[4]

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الوصف

قرش جرينلاند

إنه أحد أكبر النواع الحية من أسماك القرش، بحجم يضارع القرش الأبيض الكبير. قروش جرينلاند تنمو ليبلغ طولها 6.4 متر ووزنها 1000 كيلوگرام،[5] وربما حتى 7.3 متر وأكثر من 1400 كيلوگرام.[6][7] ومعظم قروش جرينلاند المرصودة كان يتراوح طولها في نطاق 2.44-4.8 متر ووزنها حوالي 400 كج.[6][7] والذكور عادةً ما يكونوا أصغر حجماً من الإناث. ويتنافس مع قرش الهادي النائم (الذي قد يبلغ طوله 7 أمتار) كأكبر نوع في فصيلة القروش النائمة Somniosidae. وقرش جرينلاند هو نوع thickset ببوز مستدير وقصير، وعيون صغيرة وزعانف ظهرية وصدرية بالغة الصِغر. فتحات الخياشيم صغيرة جداً بالنسبة للحجم الهائل لهذا النوع. التلون يتراوح من الكريم-الرمادي الشاحب إلى البني المسوَدّ والبدن عادة ما يكون منتظم اللون، بالرغم من الظهور أحياناً لبقع بيضاء أو خطوط داكنة شاحبة على الظهر.[6]


التسنين

تسنين قرش گرينلاند.

When feeding on large carcasses, the shark employs a rolling motion of its jaw. The teeth of the upper jaw are very thin and pointed, lacking serrations. These upper jaw teeth, numbering from 48 to 52 teeth, act as anchor while the lower jaw does the cutting. The lower teeth are interlocking and are broad and square, 50 to 52 in count, containing short, smooth cusps that point outward.[6] Teeth in the two halves of the lower jaw are strongly pitched in opposite directions.[8]

تاريخ الحياة

The Greenland shark is an apex predator mostly eating fish. Recorded fish prey have included smaller sharks, skates, eels, herring, capelin, Arctic char, cod, redfish, sculpins, lumpfish, wolffish and flounders.[6] It may also prey on marine mammals such as seals. Bite marks on dead seals at Sable Island, Nova Scotia, and Hawarden suggest that this shark may be a major predator for them in the winter.[9] Rarely, these sharks have been found as far south as the Gulf of Mexico.[10]

Greenland sharks are some of the slowest-swimming sharks, with a maximum swimming speed about half that of a typical seal. Therefore, biologists have wondered how the sharks are able to prey on the seals. Greenland sharks apparently search out seals and ambush them while they sleep.[11] Greenland sharks have also been found with remains of polar bear, horses, moose,[12] and reindeer (in one case an entire reindeer body) in their stomachs.[6][13] The Greenland shark is also known to be a scavenger, but to what extent carrion (almost certainly the origin of the reindeer) figures into the slow-moving fish's stomach contents is unknown. It is known that the species is attracted by the smell of rotting meat in the water. They often congregate in large numbers around fishing operations.[6] The shark is often colonized by the parasitic copepod Ommatokoita elongata that eats the shark's corneal tissue, rendering them blind. This parasite is reportedly bioluminescent and gives the shark a greenish glow around the eye when seen in dark waters, but this has not been scientifically supported.[6][14] The shark occupies what tends to be a very deep environment seeking its preferable cold water (−0.6 to 10 °م or 30.9 to 50.0 °ف) habitat. It has been observed at a depth of 2,200 م (7,200 قدم) by a submersible investigating the wreck of the SS Central America. A specimen videotaped at 2,773 م (9,098 قدم) off the coast of Brazil on 11 February 2012 may have been a Greenland shark, but cannot be distinguished in the video from a southern sleeper shark or Pacific sleeper shark.[15] A more typical depth for the species is above 1,200 م (3,900 قدم). During the winter, when the sharks look for warmer waters to inhabit, they are often found at or near the surface of the water.[6]

وكخارجي الحرارة، فإن قرش گرينلاند بطيء، يتحرك بسرعة 1.22 كم/س، بسرعة قصوى 2.6 كم/س.[16]

طول العمر

يُعتقد حالياً أن قرش گرينلاند هو الأطول عمراً بين كل أنواع الفقاريات على وجه الأرض.[17][18][19] فمؤخراً حدد اختبار على 28 عينة في دراسة واحدة باستخدام التأريخ بالكربون المشع أن أقدم الحيوانات المأخوذة كعينة قد عاشت لنحو 392 ± 120 سنة (حد أدنى 272 سنة وحد أقصى 512 سنة). وقد استنتج المؤلفون كذلك أن الأنواع تبلغ جنسياً في سن 150 سنة.[17]

التكاثر

As recently as 1957, females were found to not deposit eggs in the bottom mud, but retain the developing embryos within their bodies so they are born alive after an undetermined gestation period. About 10 pups per litter are normal, each initially measuring some 90 cم (35 بوصة) in length.[20]

كغذاء

لحم قرش گرينلاند يجري إعداده في هاكرل في كوخ تجفيف.

The flesh of the Greenland shark is toxic because of the presence of high concentrations of ثلاثي مثيل‌أمين أكسيد نوني (TMAO). If the meat is eaten raw or even if cooked without pretreatment, the ingested TMAO is metabolized into ثلاثي مثيل‌أمين (TMA), which can produce effects similar to extreme drunkenness. Occasionally, sled dogs that end up eating 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, whose meat is often consumed fresh.

واللحم يمكن أكله بعد غليه عدة مرات مع تغيير الماء أو بعد تجفيفه أو fermented 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.[21] It is considered a delicacy في أيسلندا.[22][23]

الأحمر: الإجمالي. الأزرق: بمياه أيسلندا.
حجم الصيد السنوي من أسماك قرش جرينلاند 1860-1894 و 1895-1925 و 1950-2010.

أساطير الإنويت

The shark is not considered dangerous to humans, though Inuit legends of this species mention them attacking kayaks.[24] Although a very large shark likely could easily consume a human swimmer, the extremely cold waters it typically inhabits makes the likelihood of attacks on humans very low, and no cases of predation on people have been verified.[6]

The Greenland shark's poisonous flesh has a high urea content, which gave rise to the Inuit legend of Ekalugsuak, the first Greenland shark.[25] The legend says that an old woman washed her hair in urine and dried it with a cloth. The cloth blew into the ocean to become Ekalugsuak.[26]

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 Sedna's urine pot, and consequently its flesh has a urine-like smell, and acts as a helping spirit to shamans.[27]

أبحاث

The Greenland Shark and Elasmobranch Education and Research Group (GEERG) has been studying the Greenland shark in the Saguenay Fjord and St. Lawrence Estuary since 2001. The Greenland shark has repeatedly been documented (captured or washed ashore) in the Saguenay since at least 1888.[26] Accidental captures and strandings have also been recorded in the St. Lawrence Estuary for over a century.

Current[حدد] research conducted by GEERG involves the study of the behaviour of the Greenland shark by observing it underwater using scuba and video equipment and by placing acoustic and satellite tags (telemetry) on live specimens; very little is known about this mysterious species.

In August 2013, researchers from Florida State University caught the first documented Greenland shark in the Gulf of Mexico. The specimen was caught at a depth of 1,749 م (5,738 قدم), where the water temperature was only 4.12 °م (39.42 °ف).[28]

انظر أيضاً


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الهامش

  1. ^ قالب:IUCN2011.2
  2. ^ Yano, K; Stevens, JD; Compagno, LJV (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): 360–73. doi:10.1007/s10228-004-0244-4.
  3. ^ Yancey, PH (2005). "Organic osmolytes as compatible, metabolic, and counteracting cytoprotectants in high osmolarity and other stresses". The Journal of Experimental Biology. 208 (15): 2819–30. doi:10.1242/jeb.01730. PMID 16043587.
  4. ^ Anthoni, U; Christophersen, C; Gram, L; Nielsen, NH; Nielsen, P (1991). "Poisonings from flesh of the Greenland shark Somniosus microcephalus may be due to trimethylamine". Toxicon. 29 (10): 1205–12. PMID 1801314.
  5. ^ Mills, Patrick (2006). Dewey, Tanya (ed.). "Somniosus microcephalus". Animal Diversity Web. University of Michigan.
  6. ^ أ ب ت ث ج ح خ د ذ ر Eagle, Dane. "Greenland shark". Florida Museum of Natural History. Retrieved 26 June 2012.
  7. ^ أ ب Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. ISBN 978-0-85112-235-9.[صفحة مطلوبة]
  8. ^ "Greenland Shark". Marinebiodiversity.ca. Centre for Marine Biodiversity. Retrieved 23 May 2011.
  9. ^ Lucas, Zoe (March 2003). "Shark Predation on Sable Island Seals". Sable Island Green Horse Society. Retrieved 26 June 2012.[نشر ذاتي سطري?]
  10. ^ "What Is a Greenland Shark Doing in the Gulf of Mexico?". Wired. 27 August 2013.
  11. ^ Scales, Helen (June 2012). "Slow Sharks Sneak Up on Sleeping Seals (and Eat Them)?". National Geographic News. Retrieved 28 December 2012.
  12. ^ "Moose-eating shark rescued in Newfoundland harbour". CBC News. 21 November 2013. Retrieved 21 November 2013.
  13. ^ Howden, Daniel (12 August 2008). "Clash of the fiercest predators as shark eats polar bear". The Independent. Retrieved 26 June 2012.
  14. ^ "Greenland Shark". Discovery. Retrieved 23 May 2011.
  15. ^ "Video: Greenland shark at over 9,100 قدم (2,800 م) deep off Brazil". The Dorsal Fin. Retrieved 21 February 2012.
  16. ^ 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. doi:10.1016/j.jembe.2012.04.021.
  17. ^ أ ب Nielsen, J; Hedeholm, RB; Heinemeier, J; Bushnell, PG; Christiansen, JS; Olsen, J; Ramsey, CB; Brill, RW; Simon, M; Steffensen, KF; Steffensen, JF (2016). "Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus)". Science. 353 (6300): 702–4. doi:10.1126/science.aaf1703.
  18. ^ Morelle, R (2016-08-12). "400-year-old Greenland shark 'longest-living vertebrate'". Science & Environment. London: BBC News.
  19. ^ Bates, M (2016-08-11). "272-Year-Old Shark Is Longest-Lived Vertebrate on Earth". Nationalgeographic.com. Washington, D.C.: National Geographic Society.
  20. ^ "Polar Seas: Greenland Shark". Elasmo-research.org. Retrieved 23 May 2011.
  21. ^ Wheatley, Gale (20 September 2010). "Iceland's Wild Culinary Traditions: Hákarl and Brennivín".
  22. ^ "My Encounter With Hákarl, The Worst Tasting Food On Earth". theexpeditioner.com.
  23. ^ "Hákarl - Icelandic Fermented Shark". Islands.
  24. ^ Stinson, Scott (24 October 2003). "Skipper Uses Knife To Kill 600-Kilo Shark". National Post. Archived from the original on 2 November 2003. Unknown parameter |deadurl= ignored (help)
  25. ^ O’Reilly, Lindsay. "The Greenland Shark", Canadian Geographic, March/April 2004. Retrieved 1 July 2007.
  26. ^ أ ب "Greenland Shark and Elasmobranch Education and Research Group". Geerg.ca. Retrieved 23 May 2011.
  27. ^ Idrobo, Carlos Julián (2008) The Pangnirtung Inuit and the Greenland Shark. p. 66. MSc Thesis. Faculty of Environment, Earth and Resources, University of Manitoba
  28. ^ Grubs, Dean (15 August 2013). "Deep-C Scientists Capture First Greenland Shark in the Gulf of Mexico"

للاستزادة

  • 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. Unknown parameter |laysummary= ignored (help)

وصلات خارجية

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