| Photo |
Smooth hammerhead
© Doug Perrine / SeaPics
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| Range Map |
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| Systematics |
Phylum: Vertebates (Chordata)
Class: Carlilagenous Fishes (Chondrichthyes)
Order: Ground sharks (Carcharhiniformes)
Family: Bonnethead sharks (Sphyrnidae)
Genus: Sphyrna (Sphyrna)
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| Name |
| Scientific: | Sphyrna zygaena |
| German: | Glatter Hammerhai |
| English: | Smooth hammerhead, Black hammerhead, Balance fish |
| French: | Requin-marteau commun |
| Spanish: | Cornuda cruz |
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| Appearance |
Large hammerhead. Broad and narrow-bladed head with a broadly arched anterior margin and no median indentation. First dorsal fin is moderately falcate with a free rear tip that is in front of the pelvic fins" origins. Origin of the first dorsal fin is over the pectoral fins insertions. Second dorsal fin is low and shorter than the anal fin. Pelvic fins are not falcate. Precaudal pit present.
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| Coloration |
Dark olive to grey-brown with white ventral surface. Undersides of pectoral fin tips are dusky colored.
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| Distribution |
Wide-ranging. Western Atlantic: Nova Scotia to Florida. Southern Brazil to Argentina. Eastern Atlantic: British Isles to Senegal. Mediterranean. Western Indian Ocean: South Africa, India, Sri Lanka, Western Pacific: Vietnam to Japan, Australia, New Zealand. Central Pacific: Hawaiian Islands. Eastern Pacific: northern California, Gulf of California, Panama, Galapagos, Equador, Chile.
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| Biology |
The only hammerhead shark that occurs in temperate waters. Lives close to shore over the continental and insular shelves as well as offshore, down to depths of 20 m. Very active. A common species that sometimes forms migrating schools.
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| Feeding |
Feeds on a variety of fishes, small sharks, rays, crustaceans and cephalopods.
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| Size |
Average size between 250 cm and 350 cm, maximum total length about 400 cm.
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| Reproduction |
Viviparous, with yolksac-placenta. 29 to 37 pups per litter. Size at birth about 55 cm.
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| Similar Species |
Other hammerheads have a similar appearance and taxonomic features have to be used to clearly distinguish.
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| Endangerment |
Status in the IUCN
Red List(1994):
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| Main criterion: |
 LR/nt (Low Risk/Near Threatened (1994)) |
| Sub criterion: |
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| Trend: |
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| Danger to Humans |
Potentially dangerous.
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