The
Hammerhead shark is a member of class
Chondrichthyes like the other
sharks (order
Lamniformes[?], family
Sphyrnidae[?], genus
Sphyrna[?]). (The only other genus of Sphyrnidae,
Eusphyra[?] contains only one species,
E. blochii, the
winghead shark[?]). Species of hammerhead range from 2-6 m long; projections on both sides of the head give these sharks a resemblance to a flattened hammer. The shark's eyes and nostrils are at the tips of the extensions. It is an aggressive
predator that eats
fish,
rays and other sharks,
cephalopods, and
crustaceans. It is found in warmer waters along coastlines and
continental shelves[?].
Of the eight species of hammerhead, three can be dangerous to humans - the scalloped, great and smooth hammerheads.
- Genus Sphyrna
- Subgenus Sphyrna
- Species: lewini (scalloped), mokarran (great), zygaena (smooth)
- Subgenus Mesozygaena[?]
- Species: corona (scalloped bonnethead)
- Subgenus Platysqualus[?]
- Species: media (scoophead), tiburo (bonnethead), tudes (smalleye)
Sharks do not have mineralized bones and rarely fossilize, but their teeth are frequently found as fossils. The hammerheads are closely related to the Charcharinid sharks[?] that evolved during the mid Tertiary. The teeth of hammerheads resemble those of some Charcharinids[?], making it difficult to be certain when the hammerheads first appeared. It is probable that the hammerheads evolved during the late Eocene, Oligocene or early Miocene.
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