A hammerhead shark has a wide, hammer-shaped head called the cephalofoil. A hammerhead has electrical sense organs called the ampullae of Lorenzini. They are small pores along the underside of its head. The pores are gel-filled and work as highly sensitive electrical receptors.
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. Scalloped hammerheads feed mainly on bony fishes, along with cephalopods such as squid and other invertebrates.
The front edge of an adult great hammerhead's head is nearly straight. A scalloped hammerhead has a notch in the middle of the front of its head.
A 2020 study describes the hammerhead family as eight living species in two genera. The great hammerhead is the biggest kind.
As of November 2026, the IUCN Red List lists the great hammerhead as Critically Endangered. It lists the scalloped hammerhead as Critically Endangered too.
Great hammerhead gestation is about 11 months, according to FishBase. 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.
Male scalloped hammerheads reach maturity at about 6 years old and about 1.5 meters long. One university animal database says a great hammerhead lives about 20 to 40 years. As of November 2026, the oldest known scalloped hammerhead was 31.5 years old, caught in the Atlantic off the coast of Brazil.
Scalloped hammerhead pups live in shallow coastal nursery areas. Young scalloped hammerheads spend their first two years inshore, and they swim together in large schools. Adult scalloped hammerheads form schools in which the sexes are mostly kept apart.
In some places huge schools of small migrating scalloped hammerheads move poleward in summer. Scalloped hammerheads migrate with the seasons. The great hammerhead is described as a solitary, nomadic and migratory species.
Words to know
- ampullae: electric-sensing pores
- genera: groups of species
- gestation: carrying pups
- poleward: toward the poles
- nomadic: always moving
