Somniosus microcephalus is found in the north Atlantic, from the coast of New England and Canada to Scandinavian waters. They occasionally venture as far south as the mouth of the Seine River in France. (Compagno and Fowler, 2005; Compagno, 1984; Compagno and Fowler, 2005; Compagno, 1984)
Somniosus microcephalus live mainly on continental and insular shelves. They occupy intertidal regions in addition to some river mouths and shallow bay areas during the winter months and often move to depths from 180 to 550 meters during warmer months. They have been observed as low as 1200 meters, with one observation at 2200 meters off the coast of Georgia - extending its range both geographically and in terms of depth. In northern parts of their range, Greenland sharks are found from 0 to 1200 meters in waters from 1 to 12 degrees Celsius. In southern parts of their range, these sharks may occur at greater depths. (Compagno and Fowler, 2005; Compagno, 1984)
Somniosus microcephalus is a large, sluggish shark that averages between 2 and 4 meters in length. Most of the body is a medium grey or brown in color and sometimes exhibits dark transverse bands or small spots or blotches that are lighter or darker than the base color. The snout is short and rounded, and the body is heavy and cylindrical in shape with small precaudal fins. No spines are present in the two equally-sized dorsal fins, and the ventral lobe of the caudal fin is slightly elongated. No anal fin is present. The skin is quite rough, exhibiting denticles with curved pointed cusps. Teeth in the upper and lower jaws differ in shape; upper teeth are spear-shaped while the lower teeth are shaped with high roots and low bent cusps for slicing. (Compagno and Fowler, 2005; Compagno, 1984; Compagno and Fowler, 2005; Compagno, 1984)
Development in Somniosus microcephalus is ovoviviparous; litters of up to ten pups have been observed. Size of fully grown young at birth has not been confirmed but is thought to be around forty centimeters. Most adults grow to between two and four meters in length. (Compagno, 1984)
Mating by this species has never been observed, but females have been found with mating scars on their caudal fins. Therefore, it is inferred that, as is the case with most sharks, males bite females until they submit. Fertilization occurs internally. ("Greenland Shark and Elasmobranch Research and Education Group", 2005)
Mating has never been observed in this species and little information is available concerning reproduction in Greenland sharks or related species. ("Greenland Shark and Elasmobranch Research and Education Group", 2005; Compagno and Fowler, 2005; Compagno, 1984)
There is no specific information on parental investment in Greenland sharks. However, most sharks are independent immediately after birth. Females provide developing embryos with rich food sources to support their development.
No specific information about the longevity of Somniosus microcephalus exists. Some scientists speculate that these sharks may live in excess of 100 years. ("Greenland Shark and Elasmobranch Research and Education Group", 2005)
Somniosus microcephalus is generally described as a sluggish. They spend much of their time hovering near the sea floor in search of food. They may also be capable of pursuing prey. These sharks have been observed exhibiting the behavior of animals that often prey on seals, even stalking a camera operator in one rare instance. However, no attacks on humans by this species have been confirmed. Greenland sharks are solitary, outside of the mating season or when large groups occur to exploit carrion, such as that produced by the commercial fishing industry. ("Greenland Shark and Elasmobranch Research and Education Group", 2005; Compagno and Fowler, 2005; Compagno, 1984; "Greenland Shark and Elasmobranch Research and Education Group", 2005; Compagno and Fowler, 2005; Compagno, 1984)
Like all sharks, Somniosus microcephalus has a lateral line which aids in the detection of movement in the surrounding waters. Sharks also have especially keen chemical perception. No communication has been observed within the species. ("Greenland Shark and Elasmobranch Research and Education Group", 2005)
Fish, marine mammals, and carrion are three staples in the diet of Somniosus microcephalus. Fish include herring (Clupeinae), salmon (Salmonidae), smelt (Osmeridae), cod (Gadidae), pollock (Theragra), haddock (Melanogrammus), halibut (Hippoglossus), redfish (Hoplostethus), sculpins (Cottoidei), lumpfish (Cyclopterus), and skates (Rajiformes). Seals (Phocidae) and small whales (Delphinidae) are also common food items. Drowned horses and reindeer have also been found in the stomachs of captured specimens. Somniosus microcephalus has been observed feeding in great numbers on carrion produced by commercial whaling and fishing operations. (Compagno and Fowler, 2005; Compagno, 1984)
There are no known predators of adult Greenland sharks because of their very large size. (Eagle, 2006)
Many of these sharks have copepod parasites, Ommatokoita elongata, attached to the corneas of their eyes. A single, female copepod will attach itself to one of the corneas, resulting in corneal damage and blindness in one eye. This does not seem to negatively effect the shark, as they do not rely on their vision. It has been suggested that the bioluminescence of these parasites helps lure prey, thus resulting in a mutualistic relationship, but there is no evidence to support this. (Compagno and Fowler, 2005; Compagno, 1984)
Somniosus microcephalus is commonly fished by people in the Arctic regions (Norway, Iceland, and Greenland) for its liver oil and meat. People of the Inuit tribes have also been known to use its skin to make boots and its teeth as knives. (Compagno and Fowler, 2005; Compagno, 1984)
The status of Greenland shark populations are not well known. They support a fishery for liver oil in Greenland, Norway, and Iceland, but some researcher suspect that populations have diminished. They have an estimated population doubling time of 14 years. (Compagno and Fowler, 2005)
Greenland sharks are also known as sleeper sharks, ground sharks, gray sharks, and gurry sharks. They are known as ekalugssuak in Greenland, hakarl in Iceland, and hakjerring in Norway. (Eagle, 2006)
Tanya Dewey (editor), Animal Diversity Web.
Patrick Mills (author), University of Michigan-Ann Arbor, Kevin Wehrly (editor, instructor), University of Michigan-Ann Arbor.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
flesh of dead animals.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
uses electric signals to communicate
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
an animal that mainly eats fish
the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
mainly lives in oceans, seas, or other bodies of salt water.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
movements of a hard surface that are produced by animals as signals to others
2005. "Greenland Shark and Elasmobranch Research and Education Group" (On-line). Accessed October 18, 2005 at http://www.geerg.ca.
Compagno, L. 1984. FAO Species Catalogue Volume 4:Sharks of the World. Rome: United Nations Development Programme.
Compagno, L., S. Fowler. 2005. Sharks of the World. Princeton, New Jersey: Princeton University Press.
Eagle, D. 2006. "Biological Profiles: Greenland shark" (On-line). Florida Museum of Natural History, Ichthyology Department. Accessed February 10, 2006 at http://www.flmnh.ufl.edu/fish/Gallery/Descript/GreenlandShark/GreenlandShark.html.