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Somniosus microcephalus

(Gray Shark)


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Family : Sleeper sharks ; Found on continental and insular shelves and upper slopes down to at least 1,200 m [1]. In the Arctic and boreal Atlantic, it occurs inshore in the intertidal and at the surface in shallow bays and river mouths during colder months, retreating to depths of 180-550 m when the temperature rises [1]. Feeds on pelagic and bottom fish , sharks and skates [2], seals and small cetaceans , sea birds, squids , crabs, amphipods , marine snails, brittle stars, sea urchins, and jellyfish [1]. Also utilized fresh and dried for human and sled-dog food (flesh is said to be toxic when fresh); eskimos also used the skin to make boots , and the sharp lower dental bands as knives for cutting hair (Ref. 247). A very sluggish shark [3].

Near Threatened

Threat status

Common Names

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Click on the language to view common names.

Common Names in Afrikaans:

Groenlandse Haai

Common Names in Bulgarian:

Гренландска акула

Common Names in Catalan, Valencian:

Tauró de Grenlàndia

Common Names in Chinese:


Common Names in Croatian:

Grenlandski morski pas

Common Names in Czech:

Žralok malohlavý

Common Names in Danish:

Almindelig Havkal, Gr, Grønlandshaj, Havhaj, Havkal, Ishaj

Common Names in Dutch:

Groenlandse Haai, Ijshaai

Common Names in English:

Gray Shark, Greenland Shark, Greenland Sleeper Shark, Ground Shark, Gurry Shark, Large Sleeper Shark, Oakettle, Sleeper, Sleeper Shark

Common Names in Faroese:


Common Names in Finnish:

Holkeri, Holkeri (kala)

Common Names in French:

Laimargue Du Groenland, Apocalle, Laimargue, Laimargue Atlantique, Requin Du Groenland

Common Names in German:

Eishai, Gr, Gröndlandhai, Grönlandhai, Grundforelle, Grundhai

Common Names in Greek (modern):

Καρχαρίας της Γροιλανδίας

Common Names in Greenlandic:


Common Names in Icelandic:


Common Names in Inuktitut:

Ekaludjuag, Ekalugss, Ekalugssuak, Ekalugssûp Piarâ, Ekalugss˚p Piarâ, Ekalukjuak, Eqaludjuaq, Eqalugssuaq, Eqalukjuag, Eqaluksuaq, Eqalukuak, Eqalusuaq, Iqalugjuaq, Iqalujjuaq, Iqalukuak

Common Names in Italian:

Lemargo, Squalo Di Groenlandia, Squalo Di Groenlandia Lemargo

Common Names in Japanese:


Common Names in Macedonian:

Гренландска ајкула спијач

Common Names in Mandarin Chinese:

小头睡鲨(大西洋睡鲨), 小頭睡鯊(大西洋睡鯊)

Common Names in Norwegian:


Common Names in Norwegian Nynorsk:


Common Names in Polish:

Rekin Polarny

Common Names in Portuguese:

Lobo, Pailona, Tubar, Tubarão da groenlândia, Tubarao Da Gronel, Tubarao Da Gronelândia, Tubarão da noite, Tubarao De Gronel, Tubarao De Gronelândia, Tubarão-Da-Noite

Common Names in Romanian:

Rechin de Groelanda

Common Names in Rumanian:

Rechin De Groelanda

Common Names in Russian:

Poljarnaja akula, Акула пол, Акула полярная атлантическая, Гренландская полярная акула

Common Names in Slovak:

Ospalec grónsky

Common Names in Spanish:

Tibur?n Boreal, Tibur, Tiburón Boreal, Tollo Boreal, Tollo De Cachos, Tollo De Groenlandia

Common Names in Spanish, Castilian:

Tiburón boreal, Tollo boreal, Tollo de Groenlandia

Common Names in Swedish:


Common Names in Turkish:

Groenlandse Haai, Grönland köpek balığı

Common Names in Ukrainian:

Акула ґренландська, Полярна акула

Common Names in Vietnamese:

Greenland shark


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Physical Description

Species Somniosus microcephalus

Distinctive Features: The Greenland shark is characterized by its large, heavy-set body which gives it a sluggish appearance and movement. It has a short, rounded snout, thin lips , and very small eyes. The dorsal and pectoral fins are very small, and it lacks spines in its dorsal fins. The gill openings are very small in comparison to its size and are located low on the sides of the shark's head .

Coloration : The Greenland shark varies between a black, brown, and grey color. Although the shark is usually uniform in color, it may often be marked with dark lines or white spots along its back and sides.

Dentition: The teeth of the Greenland shark are very different in comparison of the top and bottom sets . The upper teeth are very thin and pointy and lack serrations . They range in number from 48 to 52. The lower teeth are interlocking and are broad and square , containing short, smooth cusps that point outward. The lower teeth range in number from 50 to 52.

Denticles : The denticles of the Greenland shark are uniform in characteristics over the entire body of the shark. They are cone shaped and curved towards the rear of the shark. They are in longitudal columns and are closely spaced. They have high axial crests and low lateral crests, and the bases of the denticles have four sides.

Size, Age, and Growth: Greenland sharks average in size from 8-14 feet (244 to 427 cm) with females being the larger sex. This shark reaches a maximum length of about 21 feet (640 cm); although, it may grow to 24 feet (730 cm). Growth of the shark is very slow due to the cold temperatures of its climate.


The Greenland shark ranges in depths of 0-3,937 feet (0 to 1,200 m ) and temperatures of 34-68°F (1 to 12°C). In the north, the shark migrates near shore in search of warmer waters. It is usually spotted near the surface during the winter and retreats to depths of 591-1,804 feet (180 to 550 m) during the summer. In southern waters the shark is found near continental shelves and slopes and is found at a depth of about 3,937 feet (1,200 m). In 1988, an unmanned submarine spotted a 20 feet (6 m) long male Greenland shark at a depth of 7,218 feet (2,200 m) at the wreck of the SS Central America, which sank off the coast of Savannah, Georgia in 1857. This is 3,281 feet (1,000 m) deeper than the maximum reported depth of the shark and 273 miles (440 km ) south of its southernmost sighting in North Carolina.

Biome: Marine .

Ecology: Littoral and epibenthic , ranging from river mouths and bays to continental shelf and slope waters . Usually found in depths of 0 to 1,200 m , but one shark was observed at 2,200 m off North Carolina (Herdendorf and Berra 1995, Compagno in prep. a). During winter months in the Arctic and boreal Atlantic, the species occurs in the intertidal zone and at the surface in shallow bays and river mouths, moving into depths of 180 to 550 m during warmer months. At lower latitudes (Gulf of Maine and North Sea ) the species occurs on the continental shelves with possible movements into shallower water during spring and summer (Compagno in prep. a). Short term tracking studies of the Greenland sharks under ice off Baffin Island during late Spring suggest that individuals remained at deeper depths during the morning, gradually moving into shallower depths in the afternoon and at night (Skomal and Benz 2004). The species has been recorded in water temperatures of 0.6 to 12°C (Compagno in prep. a).

Maximum size is uncertain, but is at least 640 cm TL , possibly to 730 cm TL, however most adults are between 244 and 427 cm TL (Compagno in prep. a). Aplacental viviparous with one observed female carrying 10 young (Compagno in prep. a). Tagging studies have shown the species to be very slow growing with medium size sharks appearing to grow at a rate of 1 cm per year (Hansen 1957, Castro 1983, Castro et al. 1999).

Although reportedly sluggish, feeds on a variety of prey including invertebrates , fish, seabirds, seals as well as offal (see Compagno in prep. a for more details).

Life history parameters
Age at maturity (years): Unknown.
Size at maturity (total length cm): Unknown.
Longevity (years): Unknown.
Maximum size (total length): 640?730 cm TL.
Size at birth: ~37 to 38 cm TL (Bjerkan and Koefoed 1957, Compagno in prep. a).
Average reproductive age (years): Unknown.
Gestation time (months): Unknown.
Reproductive periodicity: Unknown.
Average annual fecundity or litter size : 10.
Annual rate of population increase: Unknown.
Natural mortality: Unknown.[4].

List of Habitats :


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The Greenland shark's most common food consists of a large variety of ocean dwellers such as other small sharks , skates , eels, herring , capelin, char, various gadoids, redfish, sculpins , lumpfish, wolfish, and flounders . Marine mammals, such as seals and porpoises , are often taken by Greenland sharks despite it being characterized as a very sluggish creature. A few Greenland shark specimens have even been found to contain an entire reindeer and parts of a horse. The shark is also known to feed off carrion and is attracted to ill-smelling meat. They often congregate in large numbers around fishing operations .


The Greenland shark is an ovoviviparous species. The female carries a large number of soft-shelled eggs eventually giving birth to full-term embryos. Some eggs have been reported to be as large as goose eggs. One 16 feet (5 m ) specimen was reported to have contained ten 15 inches (38 cm) long full-term embryos in one of its uteri.


Predators : There are no known natural predators of the mature Greenland shark , which is most likely due to its massive size.

Parasites: A common parasite of the Greenland shark is Ommatokoita elongata. This copepod attaches itself to the eyes of the shark causing corneal lesions which lead to impaired vision and even partial blindness. However, this does not significantly affect the shark since it does not rely on keen vision. On most Greenland shark specimens, usually only one eye is affected by a single female copepod. Some believe that the copepod is bioluminescent, attracting prey for the shark. However, there is no scientific evidence that supports this theory.


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Leiodon echinatum Wood • Scymnus glacialis Faber • Scymnus gunneri Thienemann • Scymnus micropterus Valenciennes • Somniosus antarcticus Whitley • Somniosus brevipinna Lesueur • Squalus borealis Scoresby • Squalus carcharis Gunnerus • Squalus microcephalus Bloch & Schneider • Squalus norvegianus Blainville • Squalus squatina (Non Linnaeus


Name Status: Accepted Name .

First described: Bloch, M .E. and J.G. Schneider M.E. Blochii, systema ichthyologiae iconibus cx illustratum. Post obitum auctoris opus inchoatum absolvit, correxit, interpolavit Jo. Gottlob Schneider, Saxo. Berolini, Sumtibus Austoris Impressum et Bibliopolio Sanderiano Commissum: Berlin. 584 p., 1801.

Last scrutiny: Data last modified by FishBase 27-Oct-2000

Yano et al. (2004) confirm that sleeper sharks found in the South Atlantic and Southern Ocean are a separate species, Somniosus antarcticus Whitley, 1939.[4].

Similar Species

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Members of the genus Somniosus

ZipcodeZoo has pages for 5 species and subspecies in this genus:

S. antarcticus (Whitely's Sleeper Shark) · S. longus (Frog Shark) · S. microcephalus (Greenland Shark) · S. pacificus (Southern Sleeper Shark) · S. rostratus (Little Sleeper Shark)

More Info

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Further Reading

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Data Sources

Accessed through GBIF Data Portal March 02, 2008:



  1. Compagno, L.J.V. (1984). FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 1. Hexanchiformes to Lamniformes. FAO Fish. Synop. (125, Vol. 4, Part 1), 249 p. [back]
  2. Compagno, L.J.V., D.A. Ebert and M.J. Smale (1989). Guide to the sharks and rays of southern Africa. New Holland (Publ.) Ltd., London. 158 p. [back]
  3. Jordan, D.S. and E.C. Starks (1895). The fishes of Puget Sound. Proc. Calif. Acad. Sci. 5:785-855. [back]
  4. Kyne, P.M., Sherrill-Mix, S.A. & Burgess, G.H. 2006. Somniosus microcephalus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <>. Downloaded on 04 February 2012. [back]
Last Revised: 2015-01-30