Great Hammerhead Shark

The great hammerhead is the largest of all hammerhead sharks. Its broad head has a nearly straight front edge with a small notch in the middle, while a tall, curved fin rises from its back. These features help distinguish it from the scalloped hammerhead and other close relatives.

That unusual head is called a cephalofoil. Its underside is dotted with tiny sensing pores that pick up the faint electrical signals made by other animals. Spread across the wide head, these sensors help the shark search the seabed for hidden prey such as stingrays.

Great hammerheads live in warm coastal and open waters around the world. They travel over continental shelves, reefs and lagoons, and also swim far offshore. Most are solitary travellers. They eat rays, bony fish, squid, crustaceans and sometimes other sharks.

One of this shark's cleverest swimming tricks looks rather surprising: it often rolls onto one side. In that position, its exceptionally tall dorsal fin works a little like an aeroplane wing. Studies of tagged sharks suggest that this posture reduces drag and helps them travel using less energy.

Great hammerheads grow slowly and females usually have pups only once every two years. This makes it hard for their populations to recover when too many sharks are caught. Fishing, accidental capture in nets and lines, and demand for shark fins have caused steep declines, and the IUCN lists the species as Critically Endangered.

Protecting great hammerheads means improving fishing rules, reducing accidental catch, safeguarding important habitats and controlling international trade. These sharks are powerful ocean predators, but they are also vulnerable animals that need time and space to recover.