WHAT TO LOOK FOR: Hammer-shaped head with a nearly straight anterior margin
The first dorsal fin is very tall and falcate.
COLOUR: Dark olive green to brownish grey above, white below. Ventral tips of
pectoral fins are not marked.
SIZE: This is the largest of the hammerhead sharks. The shark grows to a length of at
least 18.3 feet (5.6m), and may attain a length of more than 20 feet (16.1m), however,
most individuals encountered by divers are between 10 and 14 feet in length (3 to 4.3
m). Females mature at a length of 8.2 to 9.8 ft (2.5 to 3m); males mature at a length of
7.7 to 8.8 ft (2.3 to 2.7 m).
TEETH: Strongly serrate. The tooth formula is: 17-2/3-17
17-1-17
HABITAT: Coastal-pelagic and semi-oceanic shark occurring close inshore and well
offshore. Found over the continental shelves, island terraces and in passes and
lagoons of coral atolls, as well as over deep water near land. It is found near the
surface and from depths of 3 ft to more than 262 ft (1 to 80m). It often favours
continental and insular coral reefs.
DISTRIBUTION: Circumtropical
BIOLOGY:
Prey - The great hammerhead shark feeds on a wide variety of prey, but favours stingrays, groupers and sea catfishes. It also feeds on squid, crabs, tarpon, sardines,
toadfishes, porgies, grunts, jacks, herring, grouper, boxfish, other sharks, skates,
guitarfish, cownose and eagle rays .
Reproduction - Viviparous, with a yolk-sac placenta. Litters range from 13 to 42
(average 20-40) following a gestation of at least 7 months. Size at birth is 20 to 28
inches [50 to 70 cm].
BEHAVIOUR:
General - A solitary, nomadic and migratory species Some populations move
poleward during the winter.
Feeding - The shark feeds mostly at dusk. A shark was seen to use the underside of
its hammer-shaped head to bludgeon and pin a stingray to the seabed, then the shark
pivoted and bit a chunk out of the ray's pectoral fin
Mating - Mating great hammerheads were reportedly witnessed in 70 ft (21m) in the
Bahamas The sharks ascended, spiralling slowly around each other and copulated at
the surface. While synchronous swimming as a prelude to mating has been observed
with other species of sharks, copulation at the surface has not. Most species are
thought to mate at or near the seafloor.
DISPOSITION:
The species is thought to be dangerous, though few if any attacks can be attributed to
it because of the difficulty of distinguishing hammerhead species involved in attacks.
In unbaited situations the shark has approached divers without displaying aggression.
However, due to its size and broad food spectrum the shark should be treated with
caution.
Danger to humans - Due to its large size the great hammerhead shark is considered
potentially dangerous.
