A hammerhead shark has a wide head shaped like a hammer. The head has a name: the cephalofoil, also spelled cephalophoil. On an adult great hammerhead, the front edge of the head is nearly straight. A scalloped hammerhead has a notch in the middle of the front of its head. A great hammerhead's head width is less than 40% of its total length.
A hammerhead's eyes are at the two ends of its wide head. The wide-set eyes give it good sight.
A hammerhead eats fish, squid and crustaceans such as crabs. A great hammerhead favors stingrays, groupers and sea catfishes as food.
Hammerhead sharks live in warm seas around the world. A great hammerhead lives close to the shore and also far out at sea. It is often found near reefs and the bottom, in water 1 to 80 meters deep. Great hammerheads are found in water from 1 to 300 meters deep, and they are usually found in water 1 to 100 meters deep.
The great hammerhead is the biggest kind of hammerhead shark. As of November 2026, the longest great hammerhead reported was 610 cm (20 feet), and the largest published weight is 449.5 kg (991 pounds). For scalloped hammerheads, the longest reported reach 430 cm (14 feet), and the largest published weight is 152.4 kg, as of November 2026.
As of November 2026, the IUCN Red List lists the great hammerhead as Critically Endangered. The IUCN Red List also lists the scalloped hammerhead as Critically Endangered, as of November 2026.
A mother hammerhead gives birth to live pups. Great hammerhead litters of 6 to 42 pups are reported, each measuring 50 to 70 cm at birth. A mother scalloped hammerhead carries her pups for 9 to 10 months before they are born.
A female great hammerhead breeds once every two years. One university animal database says a great hammerhead lives about 20 to 40 years.
Scalloped hammerhead pups live in shallow coastal nursery areas. Young scalloped hammerheads swim together in large schools. Adult scalloped hammerheads form schools in which the sexes are mostly kept apart. Scalloped hammerheads migrate with the seasons, and some travel in large schools heading north for the summer.
Words to know
- cephalofoil: hammer-shaped head
- crustaceans: crabs and kin
- litters: groups of pups
- nursery: young sharks' home
- migrate: travel with seasons
