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Great hammerhead

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

                iGreat hammerhead

                             Conservation status

   Data deficient (DD)
            Scientific classification

   Kingdom:  Animalia
   Phylum:   Chordata
   Class:    Chondrichthyes
   Subclass: Elasmobranchii
   Order:    Carcharhiniformes
   Family:   Sphyrnidae
   Genus:    Sphyrna
   Species:  S. mokarran

                                Binomial name

   Sphyrna mokarran
   ( Rüppell, 1837)

   The great hammerhead, Sphyrna mokarran, is the largest species of
   hammerhead shark. It is found worldwide in coastal areas and above
   continental shelves in warm and tropical waters to depths of 80 m (260
   ft).

Anatomy and appearance

   It is easy to confuse the great hammerhead with the smooth hammerhead,
   Sphyrna zygaena, since both are very large hammerhead sharks.

   The great hammerhead has a thick head in which the eyes are located at
   the margins. It has a dark brown to light grey dorsal surface: this
   colour can be olive as it fades into the underside of the sharks which
   is a lighter off-white colour.

   A typical great hammerhead grows to 4 m in length and can weigh around
   230 kg (500 lb). The largest reported length is 6.1 m, and the largest
   ever caught weighed 580 kg (1,280 lb) and was 4.4 m (14.5 ft) long,
   caught in Boca Grande, Florida. However, this was a pregnant species,
   bearing 55 near-natal pups, which have obviously added to the weight.

   Expected life span of this species is approximately 20 to 30 years of
   age.

Diet

   Great hammerheads eat small sharks, rays and sting rays, squid and bony
   fish. The great hammerhead has a defense against the venom of sting
   rays, which seem to be a particular favorite in their diet. They will
   kill stingrays by using their hammer shaped head to pin them down while
   they bite the wings off the ray. They often skim the bottoms of oceans
   and stir up the sand with their heads, mouths open, to consume their
   prey. They hunt alone.

Behaviour

   When encountered by divers, the great hammerhead is usually quite shy
   and normally not aggressive. The International Shark Attack File
   classifies the great hammerhead as one of the least dangerous sharks
   with only one provoked attack, but an unspecified hammerhead which
   might include the great hammerhead is on seventh place, so this shark
   is to be considered dangerous but not extremely aggressive.

Reproduction

   Great hammerheads are viviparous. They give birth to a litter of
   between 6 and 55 young, typically 20 to 40. The gestation period is 11
   months. Size at birth is about 60 to 70 cm. Females mature at about 2.1
   to 2.5 m and males at about 2.25 to 2.7 m.
   Retrieved from " http://en.wikipedia.org/wiki/Great_hammerhead"
   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.
