Elasmobranchii (sharks and rays) > Carcharhiniformes
(Ground sharks) > Sphyrnidae
(Hammerhead, bonnethead, or scoophead sharks)
Etymology: Eusphyra: Greek, eu = good + Greek, sphyra = hammer (Ref. 45335).
Environment / Climate / Range
Marine; brackish; benthopelagic; amphidromous (Ref. 51243). Tropical; 31°N - 20°S, 47°E - 154°E
Length at first maturity / Size / Weight / Age
Maturity: Lm ?, range 120 - ? cm
Max length : 186 cm TL male/unsexed; (Ref. 6871)
soft rays: 0. Grey or grey-brown above, paler below. Expanded lateral blades of head very narrow and wing-like, with a series of small bumps along edges in front of nostrils; width across head 40 or 50% of total length. Nostrils enormously expanded, each nearly 2 times the mouth head (Ref 13562).
Indo-West Pacific: Persian Gulf to the Philippines, north to China, south to Australia.
Found in shallow water on continental and insular shelves (Ref. 244). Enters estuaries (Ref. 4832). Feeds mainly on small teleost fishes but also takes crustaceans and cephalopods (Ref. 13562). Viviparous (Ref. 50449), with 6 to 25 pups in a litter (Ref. 6871). Has a remarkable wing-shaped head which is nearly or quite half of its body length, the function of which is uncertain, maybe for maneuvering or for increasing the surface area of some of the sense organs (Ref. 244). Probably harmless to people (Ref. 13562). Caught commonly, but in low numbers, by inshore gillnet fisheries. Particularly common in catches off Kalimantan (Ref.58048). Probably a common fisheries species where it occurs (Ref. 13562). Meat utilized for human consumption; liver is a source of vitamin oil (Ref. 244). Offal probably utilized for fishmeal (Ref. 13562). Reported to reach 300 cm TL (Ref. 58784).
Viviparous, placental (Ref. 50449), with 6 to 25 in a litter after a gestation period of 8 (Ref.58048) -11 months (Ref. 6871). Size at birth between 32 and 45 cm TL (Ref. 13562).
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. (Ref. 244)
IUCN Red List Status (Ref. 96402)
CITES (Ref. 94142)
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 1.0010 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00389 (0.00188 - 0.00805), b=3.26 (3.08 - 3.44), based on LWR estimates for species & Family-body shape (Ref. 93245
Trophic Level (Ref. 69278
): 4.2 ±0.6 se; Based on diet studies.
Resilience (Ref. 69278
): Very Low, minimum population doubling time more than 14 years (Fec=6).
Vulnerability (Ref. 59153
): High vulnerability (63 of 100) .