Scalloped hammerhead

Scalloped hammerhead
Conservation status
Endangered  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	Carcharhiniformes
Family:	Sphyrnidae
Genus:	Sphyrna
Species:	S. lewini
Binomial name
Sphyrna lewini (Griffith & Hamilton Smith, 1834)

File:6151 aquaimages.jpg

School of scalloped hammerheads, Wolf Island, Galapagos Islands.

The scalloped hammerhead, Sphyrna lewini, is a hammerhead shark of the family Sphyrnidae. Originally Zygaena lewini, it was later moved to its current name. The Greek word sphyrna translates into "hammer" in English, referring to the shape of this shark's head.

This shark is also known as the bronze, kidney-headed or southern hammerhead. It primarily lives in warm temperate and tropical coastal waters all around the globe between latitudes 46° N and 36° S, down to a depth of 300 m. It is the most common of all hammerheads.

Anatomy and appearance

The most distinguishing characteristic of this shark, as in all hammerheads, is the 'hammer' on its head. The shark's eyes and nostrils are at the tips of the extensions. The maximum length of the scalloped hammerhead is 4.3 m and the maximum weight 150 kg.

Behavior

This shark is often seen during the day in big schools, sometimes numbering hundreds. They are considered dangerous but are normally not aggressive towards humans, in fact most incidents with humans are probably defensive after the shark was surprised or frightened.

Diet

This shark feeds primarily on fish such as sardines, mackerel and herring, and occasionally on cephalopods such as squid and octopus. Larger specimens may also feed on smaller species of shark such as the blacktip reef shark, Carcharhinus melanopterus.

Reproduction

Viviparous, producing 15 to 31 pups in a litter, measuring 43 to 55 cm.

See also

• List of sharks

References

• Template:IUCN2006 Database entry includes justification for why this species is near threatened
• "Sphyrna lewini". Integrated Taxonomic Information System. 23 January. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
• Froese, Rainer; Pauly, Daniel (eds.) (2005). "Sphyrna lewini" in FishBase. 09 2005 version.

External links

• ARKive - images and movies of the scalloped hammerhead (Sphyrna lewini)
• Shark Info page about the scalloped hammerhead