Großer Hammerhai

2008-06-13T07:17:44Z

203.27.235.5:

{{Expand|date=May 2008}}
{{Taxobox

| color = pink
| name = Great hammerhead
| image = Spmok u0.gif
| image_width = 240px
| status = EN
| trend = unknown
| status_system = iucn2.3
| status_ref = <ref name="iucn">{{IUCN2007|assessors=Denham|year=2000|id=39386|title=Sphyrna mokarran|downloaded=15 December 2007}}</ref>
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Chondrichthyes]]
| subclassis = [[Elasmobranchii]]
| ordo = [[Carcharhiniformes]]
| familia = [[Sphyrnidae]]
| genus = ''[[Sphyrna]]''
| species = '''''S. mokarran'''''
| binomial = ''Sphyrna mokarran''
| binomial_authority = ([[Eduard Rüppell|Rüppell]], 1837)
}}
{{Sharksportal}}

The '''great hammerhead''', ''Sphyrna mokarran'', is the largest species of [[hammerhead shark]]. It is found worldwide in [[coast]]al areas and above [[continental shelves]] in warm and [[tropical]] waters to depths of 80 [[metre|m]] (260 [[foot (measurement)|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 color.If the hulking great white is the B52 of the shark world, the great hammerhead must be the stealth bomber, with its sinister angles and sci-fi look. And, of course, there's the massive head. It is widely accepted that the 'hammer' design succeeds in spreading its electromagnetic receptors, eyes and nostrils over a larger area. Recent studies suggest it could have a dual purpose: the broad, flat head gives it added lift while swimming, and might increase manoeuvrability.

The average great hammerhead shark is up to 11.5 feet (3.5 m) long. The largest reported was 20 feet (6 m) long and of unknown weight. These large sharks average about 500 pounds (230 kg) but can weigh as much as 1,000 pounds (450 kg). The heaviest ever caught weighed 580 kg (1,280 lb) but was only 4.4 m (14.5 ft) long, caught in [[Boca Grande, Florida]]<ref name="WR">[http://www.firstcoastnews.com/news/florida/news-article.aspx?storyid=58228 Firstcoastnews.com | Jacksonville, St. Augustine and Brunswick | Port Charlotte Man Catches 1,280 Pound Hammerhead Shark]</ref>. However, this was a pregnant specimen, bearing 55 near-[[Birth|natal]] pups, which have obviously added to the weight.

Expected life span of this species is approximately 20 to 30 years of age.
<ref name="flmnh">[http://www.flmnh.ufl.edu/fish/Gallery/Descript/GreatHammerhead/GHammerhead.html Florida Museum of natural history]</ref>

==Diet==
Great hammerheads eat small sharks, [[Rajiformes|rays]] and [[sting ray]]s, [[squid]] and [[bony fish]]. The great hammerhead has a defense against the [[Venom (poison)|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 also hunt alone.

==Behavior==
Partly because no one really knows what to expect from a great hammerhead and partly because of its size, it is frequently classed as an exceptionally dangerous species, alongside those other 'villains', the bull, great white and tiger sharks.
When encountered by [[underwater diving|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 reputed attack, but an unspecified hammerhead which might include the great hammerhead is on tenth place, so this shark is to be considered dangerous but not extremely aggressive.
<ref name="ISAF">[http://www.flmnh.ufl.edu/fish/sharks/statistics/species2.htm International Shark Attack File]</ref>

==Reproduction==
Great hammerheads are [[viviparous]]. They give birth to a litter of between 6 and 55 young, typically 20 to 40.[http://www.sptimes.com/2006/06/30/State/Catch_is_a_big_inside.shtml] 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.

==References==
* {{ITIS|ID=160515|taxon=Sphyrna mokarran|year=2006|date=23 January}}
* {{FishBase_species|genus=Sphyrna|species=mokarran|year=2005|month=09}}
* {{marinebio|id=87|name=Great Hammerhead shark, ''Sphyrna mokarran''}}
<references/>

==External links==
* [http://www.shark-pictures.com/pictures/great-hammerhead-shark.html Great Hammerhead Shark Pictures] - Great Hammerhead Shark Pictures at Shark-Pictures.com
* ARKive - [http://www.arkive.org/species/GES/fish/Sphyrna_mokarran/ images and movies of the great hammerhead ''(Sphyrna mokarran)'']

[[Category:Sphyrnidae]]
[[Category:Viviparous fish]]

[[ca:Gran tauró martell]]
[[de:Großer Hammerhai]]
[[es:Sphyrna mokarran]]
[[fr:Grand requin-marteau]]
[[it:Sphyrna mokarran]]
[[nl:Grote hamerhaai]]
[[ja:ヒラシュモクザメ]]
[[no:Hammerhai]]
[[fi:Isovasarahai]]
[[sv:Stor hammarhaj]]

Wikipedia - Benutzerbeiträge [de]

Großer Hammerhai