Great hammerhead

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iGreat hammerhead

Data deficient (DD)^[1]

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)

Sharks Portal

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).

1 Anatomy and appearance
2 Diet
3 Behavior
4 Reproduction
5 References
6 External links

[edit] 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^[2]. 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.

[edit] 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.

[edit] Behavior

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. ^[3]

[edit] Reproduction

Great hammerheads are viviparous. They give birth to a litter of between 6 and 55 young, typically 20 to 40.[2] 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.

[edit] References

Sphyrna mokarran (TSN 160515). Integrated Taxonomic Information System. Accessed on 23 January 2006.
"Sphyrna mokarran". FishBase. Ed. Ranier Froese and Daniel Pauly. 09 2005 version. N.p.: FishBase, 2005.
Great Hammerhead shark, Sphyrna mokarran MarineBio"

^ Denham (2000). Sphyrna mokarran. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006. Database entry includes a brief justification of why this species is listed as data deficient
^ [1]
^ International Shark Attack File