Sphyrna tiburo (Linnaeus, 1758)
Bonnethead
Sphyrna tiburo
photo by Murch, A.

Family:  Sphyrnidae (Hammerhead, bonnethead, or scoophead sharks)
Max. size:  150 cm TL (male/unsexed); max.weight: 11 kg; max. reported age: 12 years
Environment:  reef-associated; brackish; marine; depth range 10 - 80 m
Distribution:  Western Atlantic: North Carolina, USA to southern Brazil, including Cuba and the Bahamas. Caribbean and Gulf of Mexico; rare in Bermuda (Ref. 26938). Eastern Pacific: southern California, USA to Ecuador.
Diagnosis:  Front of head semicircular in outline. No other hammerhead has front of head in semicircle. (Ref. 26938).
Biology:  Found on the continental and insular shelves, on inshore and coastal areas, over mud and sand bottoms, also on coral reefs. Often occur in shallow water including estuaries, shallow bays and over coral reefs (Ref. 9987). Spends night time hours on shallow grass flats, searching for nocturnally active invertebrate prey, moves into deeper water during the day (Ref. 27549). Feed mainly on crustaceans, also on bivalves, octopi, and small fish. Viviparous, with 6 to 9 young per litter. Size at birth about 35 to 40 cm. Not territorial. Always occurs in small groups. Considerable sexual segregation occurs. Shows diel rhythm of activity. Utilized for human consumption and processed for fishmeal.
IUCN Red List Status: Endangered (EN); Date assessed: 02 July 2019 (A2bcd) Ref. (130435)
Threat to humans:  harmless
Country info:  No specimens available. Those reported from Navotas, Manila Bay, Luzon (Ref. 47939) and recorded in 1936-1937 collections from Zamboanga Province, Mindanao (Ref. 280) may be based on a vaguely similar hammerhead such as the young of S. mokarran (Ref. 47737). Unsubstantiated records outside the Western Hemisphere (Ref. 48449). Also Ref. 110893, 125614.


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