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 Scalloped hammerhead (Sphyrna lewini)

  Index
> Photo
> Range Map
> Systematics
> Name
> Appearance
> Coloration
> Distribution
> Biology
> Feeding
> Size
> Reproduction
> Similar Species
> Endangerment
> Danger to Humans

 Photo

Scalloped hammerhead
© Doug Perrine / SeaPics
 Range Map

Earth Map


 Systematics

Phylum: Vertebates (Chordata)

Class: Carlilagenous Fishes (Chondrichthyes)
  Order: Ground sharks (Carcharhiniformes)
    Family: Bonnethead sharks (Sphyrnidae)
      Genus: Sphyrna (Sphyrna)


 Name

Scientific: Sphyrna lewini
German: Bogenstirn-Hammerhai
English: Scalloped hammerhead
French: Requin-marteau halicorne
Spanish: Cornuda comun


 Appearance

Large, with a broad, narrow-bladed head. Anterior margin of "hammer" is very broadly arched in adults, with a prominent median indentation. Somewhat falcate first dorsal fin with an origin over or behind the insertion of the pectoral fins. Free rear end of second dorsal fin nearly reaches caudal fin. With precaudal pit.

 Coloration

Grey-brown (olive), with white ventral surface. Dusky to black pectoral fin tips. Juveniles can have dusky coloration on the tips of the pelvic fins, the lower lobe of caudal fin and the free rear end of the second dorsal fin.

 Distribution

Nearly circumglobal in tropical, subtropical and warm-temperate waters. Western Atlantic: New Jersey to Brazil, Gulf of Mexico, Caribbean and Bahamas. Eastern Atlantic: Senegal to Zaire. Mediterranean. Indo-Western Pacific: South Africa to Red Sea, Pakistan, India, Maldives, Thailand. Western Pacific: Indonesia, China, Japan, Australia, New Caledonia. Central Pacific: Hawaii, Tahiti. Eastern Pacific: Southern California to Equador.

 Biology

Probably the most abundant hammerhead species in coastal waters. Can even occur in river mouths and estuaries. Found from the very surface down to about 275 m with juveniles living in shallow waters that serve as nursery grounds. Scalloped hammerheads can form seasonal aggregations or live solitary. Both migrating and stationary populations are known.

 Feeding

Fishes (e.g. sardines, herrings, anchovies), invertebrates, mainly cephalopods), small sharks (e.g. Atlantic sharpnose sharkBlacktip reef shark ).

 Size

Average size between 250 cm and 300 cm, maximum total length about 370 cm to 420 cm.

 Reproduction

Viviparous, with yolksac-placenta (gives birth to live young). Size at birth between 40 cm and 55 cm. Gestation period lasts between 9 and 10 months. Males reach sexual maturity at about 140 cm to 160 cm, females at approximately 200 cm. Pups are born in very shallow water (nursery grounds).

 Similar Species

Three other species occur in the same area as the scalloped hammerhead but they can be identified by the shape of their "hammer," their first dorsal fin, and their color. The Great hammerhead and the Smooth hammerhead have a similar, general distribution whereas the only overlaps in the area of the Ivory Coast.

 Endangerment

Status in the IUCN Red List(1994):

Main criterion: > LR/nt (Low Risk/Near Threatened (1994))
Sub criterion:
Trend: Unknown


 Danger to Humans

Potentially dangerous.



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