Somniosus microcephalus
Greenland Shark [+]
Description & Behavior
The Greenland shark, Somniosus microcephalus (Bloch and Schneider, 1801), aka sleeper shark, is named for its lethargic behavior and Somniosus, which refers to "sleep", and microcephalus which means "small head." In spite of its small head, the Greenland shark is a large, robust shark that reaches up to 6.5 m in length and weighs up to 900 kg. It has a short, rounded snout, small eyes, and small but sharp teeth. The dorsal and pectoral fins are also quite small, as are the gill slits in relation to the Greenland shark's body size. They are brown, gray, or black in color, and some may have dark lines or white spots on the dorsal side or along the flanks.
World Range & Habitat
The Greenland shark, Somniosus microcephalus, is found between 80°N-55°S in the northern Atlantic and Arctic regions, although sightings have been reported near France and Portugal, as far west as the Gulf of St. Lawrence, and as far south as Cape Cod and North Carolina. Sightings have also been reported in the Southern Atlantic near Argentina and in Antarctic waters. The Greenland shark is a deep-water species that inhabits cold waters between 1-12°C, near the continental and insular shelves and upper slopes down to at least 1,200 m. In the Arctic and subarctic Atlantic, however, the Greenland shark can be found during colder months inshore in the intertidal and at the surface of shallow bays and river mouths.
Feeding Behavior (Ecology)
The Greenland shark, Somniosus microcephalus, feeds on pelagic and bottom fish, other sharks, skates, eels, seals, small cetaceans, sea birds, squids, crabs, amphipods, marine snails, brittle stars, sea urchins, and jellyfish (just about anything). The Greenland shark is also known to feed on carrion, and even reindeer and a horse have found in the stomachs of Greenland sharks.
Life History
The Greenland shark, Somniosus microcephalus, is an ovoviviparous species. Pups measure about 38 cm at birth and litter size is between 5-10 young.
Ovoviviparous: eggs are retained within the body of the female in a brood chamber where the embryo develops, receiving nourishment from a yolk sac. This is the method of reproduction for the "live-bearing" fishes where pups hatch from egg capsules inside the mother's uterus and are born soon afterward. Also known as aplacental viviparous.
Conservation Status/Additional Comments
The Greenland shark is hunted commercially and recreationally. The meat is dried and sold for human and dog consumption. In its fresh form, the flesh is said to be toxic when eaten because the flesh contains high concentrations of urea and trimethylamine oxide, which induces a intoxicating affect (see Eating Rotten Shark Meat).
References & Further Research
BioOne ~ CITES ~ Discover Life ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList ~ MarineBio Network ~ NCBI ~ SCIRIS ~ SIRIS ~ Tree of Life Web Project ~ Wikipedia
Florida Museum of Natural History, Ichthyology Division
Arctic Kingdom Marine Expeditions - ANIMALS / Greenland Shark (image galleries)
Search the Web for Greenland Shark » ARKive ~ Ask.com ~ Ask Jeeves ~ bing ~ deviantART ~ dmoz ~ Dogpile ~ Google Images ~ MySpace Images ~ OceanFootage ~ Picsearch ~ StumbleUpon ~ Yahoo! Images ~ YouTube
