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Scalloped Hammerhead
Sphyrna lewini (Griffin & Smith, 1834)

Female (upper - 36 cm long) and male (37 cm) Scalloped Hammerhead pups from the Australian Museum Fish Collection (AMS I.41725-001 and -002). The adult female was caught on hook and line at a depth of 430 m, off Port Hacking, New South Wales, October 2002. View larger image.

The anterior region of a male Scalloped Hammerhead pup. Note the large eye and the distinctive undulating front margin of the head. View larger image.

Lower surface of the head of a female Scalloped Hammerhead pup. Note the pattern of pores. Each pore is the external opening of an ampulla of Lorenzini (see text). View larger image.

The Scalloped Hammerhead has an undulating margin to the front of the head with an indentation medially. It has a low second dorsal fin and a relatively straight posterior pelvic fin margin.

This species is brownish-grey to olive or bronze above and pale below. Adults have dusky pectoral fin tips, but no other markings. Juveniles have dark pectoral, lower caudal and second dorsal fin tips.

The Scalloped Hammerhead grows to 4.2 m in length. It is considered a potentially dangerous species that has occasionally displayed its threat posture to scuba divers who have approached too closely (Thomson et al, 1979).

Scalloped Hammerheads occur in most tropical and warm temperate waters worldwide. They are found in coastal and offshore waters. It is not an oceanic species.

In Australia it is known from north-western Western Australia, around the tropical north and south to the central coast of New South Wales.

View a map of the collecting localities of specimens in the Australian Museum Fish Collection.

Sharks can detect weak electrical fields using electrical sense organs called the ampullae of Lorenzini. These are connected to the exterior via pores in the shark's snout (see lower image). This ability allows some species to detect the electrical cues that emanate from prey animals and even the weak electrical currents flowing through the earth's magnetic fields. Some species can detect voltages as low one millionth of a volt.

Related links

• View the Sharks list
• View the family Sphyrnidae list
• View low resolution movie clips 47k (wmv) and 98k (mov).
• Go to the movies page for higher resolution versions.

Further reading

1. Allen, G.R. 1997. Marine Fishes of Tropical Australia and South-east Asia. Western Australian Museum. Pp. 292.
2. Allen, G.R. & R. Swainston. 1988. The Marine Fishes of North-Western Australia. A Field Guide for Anglers and Divers. Western Australian Museum. Pp. 201.
3. Compagno, L.J.V. 1984. FAO species catalogue. Vol. 4, Sharks of the World. An annotated and illustrated catalogue of shark species known to date. Part 2 - Carcharhiniformes. iii-x, 251-655.
4. Hutchins, B. & R. Swainston. 1986. Sea Fishes of Southern Australia. Complete Field Guide for Anglers and Divers. Swainston Publishing. Pp. 180.
5. Klimley, A.P. 1993. Highly directional swimming by scalloped hammerhead sharks, Sphyrna lewini,and subsurface irradiance, temperature, bathymetry and geomagnetic field. Marine Biology. 117: 1-22.
6. Last, P.R. & J.D. Stevens. 1994 Sharks and Rays of Australia. CSIRO. Pp. 513.
7. Randall, J.E., Allen, G.R. & R.C. Steene. 1997. Fishes of the Great Barrier Reef and Coral Sea. Crawford House Press. Pp. 557.
8. Stevens, J.D. 1987. Sharks. Golden Press. Pp.240.
9. Thompson, D.A., Findley, L.T. & A.N. Kerstitch. 1979. Reef Fishes of the Sea of Cortez. John Wiley & Sons. Pp. 302.