• Blue Shark

    Category: Sea Life

    Blue sharks mainly inhabit the open-ocean waters of the Mediterranean Sea and every ocean except the Arctic. Some frequent shallower waters close to continental shelves. They feed on cephalopods, including the pelagic octopus; and schooling fishes, such as snake mackerel. Their average lifespan is 15 years in the wild and 8 years in captivity.

    Blue Shark

    Blue Shark

    Scientific & Common Names

    Kingdom - Animalia

    Phylum - Chordata

    Class - Chondricthyes

    Subclass - Elasmobranchii

    Order - Carcharhiniformes

    Family - Carcharhinidae

    Genus - Prionace

    Species - P. glauca

    Common Names - Blue Shark, Blue Whaler, Blue Dog

    Characteristics

    Blue sharks have bright blue flanks, a deep indigo upper side and a gray underside that helps hide them from prey and predators. They have a long, thin body shape with a tail fin that is longer than many other shark species, as well as big eyes and multiple rows of serrated teeth. Adult blue sharks reach an average length of 11 feet and can weigh up to 528 pounds.

    Breeding

    Blue sharks breed during summer, and females then go through a gestation period that lasts 9 to 12 months. They give birth to anywhere from 25 to 130 offspring between December and April in the northern Pacific Ocean. Females nourish their young during their gestation period, but do not provide parental care once their offspring are born. Young sharks grow rapidly and reach maturity when they are around 5 years old.

    Behavior

    Blue sharks have a special sensory organ called the lateral line that helps them detect movement, as well as electroreceptors that detect electrical impulses made by muscle movements. They use these senses to find prey. Blue sharks use body language to show aggression and sometimes travel in schools with other members of their gender. They do not form their own territories and migrate for reproductive and hunting purposes.

    History

    Blue sharks are still found throughout their historic range, although their population is believed to have declined over the years. Blue sharks are mentioned in the Ancient Greek poem on fishing, Halieutica, by Oppian. In the poem they are described as excellent parents. While this is not true, the myth is still occasionally brought up as a fact.

    Present status

    The blue shark is currently listed as Near Threatened. It is the most heavily fished shark in the world. The main threats include shark finning, being caught unintentionally by dragnet and longline fishing methods, and being caught intentionally by sport fishermen. Conservation efforts include prohibitions on finning in certain areas, limits on how many blue sharks can be unintentionally or intentionally caught and the establishment of carefully managed shark fisheries in the Gulf of Mexico and Atlantic Ocean.

    References

    1. http://animaldiversity.ummz.umich.edu/accounts/Prionace_glauca/

    2. http://www.iucnredlist.org/details/full/39381/0

    3. http://www.flmnh.ufl.edu/natsci/ichthyology/gallery/Descript/BlueShark/BlueShark.html

    4. Sharks of the World, 2005, Leonard Compagno and Sarah Fowler

    5. The Sharks of North America, 2011, Jose I. Castro

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