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Blue shark

2007 Schools Wikipedia Selection. Related subjects: Insects, Reptiles and
Fish

                   iBlue shark

                             Conservation status

   Near Threatened (LR/nt)
            Scientific classification

   Kingdom:  Animalia
   Phylum:   Chordata
   Class:    Chondrichthyes
   Subclass: Elasmobranchii
   Order:    Carcharhiniformes
   Family:   Carcharhinidae
   Genus:    Prionace
             Cantor, 1849
   Species:  P. glauca

                                Binomial name

   Prionace glauca
   (Linnaeus, 1758)
   Range of blue shark
   Range of blue shark

   The blue shark, Prionace glauca is a carcharhinid shark which is found
   in the deep waters of the world's temperate and tropical oceans. They
   prefer cooler waters and are not found, for example, in the Gulf of
   Mexico, the Adriatic or Red Sea. Blue sharks are known to migrate long
   distances, from New England to South America for example. Although
   generally lethargic, they are capable of moving very quickly if the
   need arises. Blue sharks are viviparous and are noted for their large
   litters of 25 to over 100 pups. They feed primarily on small fish and
   squid, although they are perfectly capable of taking larger prey should
   the opportunity present itself. They are often found in schools
   segregated by sex and size.

Distribution and habitat

   The blue shark is an oceanic and epipelagic shark found worldwide in
   deep temperate and tropical waters from the surface to about
   350 meters. In temperate seas it may come closer to shore where it can
   be observed by divers, while in tropical waters it occurs at greater
   depths. It is found from as far north as Norway to as far south as
   Chile. In the Pacific its greatest concentrations occur between 20° and
   50° North but with strong seasonal fluctuations. In the tropics it is
   uniformly distributed between 20° N and 20° S. It prefers waters with a
   temperature range of 7–16° C but will tolerate temperatures of 21° C or
   above. It is highly migratory with records from the Atlantic showing a
   regular clockwise migration within the prevailing currents.

Anatomy and appearance

   Livery of Prionace glauca.
   Enlarge
   Livery of Prionace glauca.

   Blue sharks are light-bodied with long pectoral fins. The top of the
   body is deep blue and lighter on the sides. The underside of the shark
   is white. The animal grows to 3.8  meters or more, but the usual size
   is 1.8 to 2.4 m. The shark's typical weight is 60 to 80  kg. The
   largest recorded specimen weighed 205 kg. Blue sharks in the Pacific
   are generally smaller and do not exceed 2 m (6 ft). They are not
   typically confused with any other species.

Diet

   Squid are an important prey item for blue sharks, but their diet also
   comprises other invertebrates such as cuttlefish and pelagic octopuses,
   as well as lobster, shrimp, crab, a large number of bony fishes, small
   sharks, mammalian carrion and occasional sea birds Whale and porpoise
   blubber and meat have been retrieved from the stomachs of captured
   specimens and they are known take cod from trawl nets.

Reproduction

   They are vivaporous, with a yolk-sac placenta, delivering 4 to 135 pups
   per litter. The gestation period is between 9 and 12 months. Females
   mature at 5 to 6 years of age and males at 4 to 5. Courtship is
   believed to involve biting by the male, as mature specimens can be
   accurately sexed according to the presence or absence of bite scarring.
   Female blue sharks have adapted to the rigours of the mating ritual by
   developing skin 3 times as thick as that of the male.

Importance to humans

   Blue sharks are the most heavily fished sharks in the world mainly as
   result of bycatch. It is estimated that 10 to 20 million individuals
   are killed each year as a result of fishing.. The flesh is edible, but
   not widely sought after; it is utilized fresh, dried, smoked and salted
   and for fishmeal. The skin is used for leather, the fins for shark-fin
   soup and the liver for oil. Blue sharks are occasionally sought as game
   fish and they are frequent accidental catches by commercial fisherman
   seeking swordfish or tuna. Most interaction between blue sharks and
   humans takes place in deep water as they rarely venture close to shore.
   There are several documented attacks by blue sharks on people and
   boats.

   Retrieved from " http://en.wikipedia.org/wiki/Blue_shark"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
