Elasmobranchii (sharks and rays) > Carcharhiniformes
(Ground sharks) > Sphyrnidae
(Hammerhead, bonnethead, or scoophead sharks)
Etymology: Sphyrna: Greek, sphyra = hammer (Ref. 45335).
Environment / Climate / Range
Marine; brackish; pelagic-oceanic; oceanodromous (Ref. 13562); depth range 0 - 200 m (Ref. 5578), usually 0 - 20 m (Ref. 55303). Subtropical; 59°N - 55°S, 180°W - 180°E
Length at first maturity / Size / Weight / Age
Maturity: Lm ?, range 265 - ? cm
Max length : 500 cm TL male/unsexed; (Ref. 35388); common length : 335 cm TL male/unsexed; (Ref. 13562); max. published weight: 400.0 kg (Ref. 9987)
soft rays: 0. A large hammerhead with a notch at the center of head; 1st dorsal fin moderately high, 2nd dorsal and pelvic fins low (Ref. 5578). Olive-grey or dark grey above, white below (Ref. 5578). Fins nearly plain, dusky or blackish tipped (Ref. 13562).
Widespread in temperate and tropical seas (Ref. 13562). Western Atlantic: Canada to the Virgin Islands; Brazil to Argentina. Eastern Atlantic: British Isles to Côte d'Ivoire, including the Mediterranean. Indo-Pacific: South Africa to Sri Lanka; southern Siberia to Viet Nam (Ref. 13562); southern Australia, New Zealand, and Hawaii (Ref. 13562). Eastern Pacific: northern California, USA to Chile.
Occurs inshore and well offshore (Ref. 5578), over continental and insular shelves (Ref. 244). Coastal, pelagic, and semi-oceanic, but often bottom associated at 1-139 m (Ref. 58302). Migrates northward in summer; young often in large aggregations of hundreds of individuals (Ref. 13562). Prefers to feed on small sharks, skates and stingrays, but also preys on bony fishes, shrimps, crabs, barnacles and cephalopods (Ref. 244). Viviparous (Ref. 50449). Regarded as being dangerous to people, though only few can be tentatively attributed to this species due to its occurrence in temperate waters (Ref. 244). Reported to cause poisoning (Ref. 4690). Caught occasionally by shark and tuna longline fisheries (Ref.58048). Meat utilized fresh, dried-salted, and possibly smoked for human consumption; liver oil for vitamins, fins for soup, hide for leather, and carcasses for fishmeal (Ref. 244). Used in Chinese medicine (Ref. 12166). Become sexually mature when 250 to 300 cm long. The female gives birth to 30 - 40 young (Ref. 35388).
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. FAO Fish. Synop. 125(4/2):251-655. Rome: FAO.
IUCN Red List Status (Ref. 90363)
Fisheries: commercial; gamefish: yes
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates of some properties based on empirical models
Phylogenetic diversity index (Ref. 82805
= 0.5059 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00267 (-0.17373 - 0.17908), b=3.16 (3.06 - 3.26), based on LWR estimates for species & family-BS (Ref. 93245
Trophic Level (Ref. 69278
): 4.5 ±0.8 se; Based on diet studies.
Resilience (Ref. 69278
): Low, minimum population doubling time 4.5 - 14 years (Fec=20-50).
Vulnerability (Ref. 59153
): Very high vulnerability (82 of 100) .