Hammerhead Shark
Sphyrna

Photo: Hammerhead shark
Hammerheads are aggressive hunters, feeding on smaller fish, octopuses, squid, and crustaceans. They do not actively seek out human prey, but are very defensive and will attack when provoked.
Photograph by Brian J. Skerry
Map: Locator map for the hammerhead shark
 Hammerhead Shark range

Fast Facts

Type: Fish
Diet: Carnivore
Average lifespan in the wild: 20 to 30 years
Size: 13 to 20 ft (4 to 6 m)
Weight: 500 to 1,000 lbs (230 to 450 kg)
Did you know? Hammerheads use their wide heads to attack stingrays, pinning the winged fish against the sea floor.

Hammerhead sharks are consummate predators that use their oddly shaped heads to improve their ability to find prey. Their wide-set eyes give them a better visual range than most other sharks. And by spreading their highly specialized sensory organs over their wide, mallet-shaped head, they can more thoroughly scan the ocean for food.

One group of sensory organs is the ampullae of Lorenzini, which allows sharks to detect, among other things, the electrical fields created by prey animals. The hammerhead's increased ampullae sensitivity allows it to find its favorite meal, stingrays, which usually bury themselves under the sand.

The great hammerhead is the largest of the nine identified species of this shark. It can grow up to 20 feet (6 meters) in length and weigh up to 1,000 pounds (450 kg), although smaller sizes are more common.

Found in temperate and tropical waters worldwide, far offshore and near shorelines, hammerheads are often seen in mass summer migrations seeking cooler water. They are gray-brown to olive-green on top with off-white undersides, and they have heavily serrated, triangular teeth. Their extra-tall, pointed dorsal fins are easily identifiable.

Most hammerhead species are fairly small and are considered harmless to humans. However, the great hammerhead's enormous size and fierceness make it potentially dangerous, though few attacks have been recorded.

Hammerhead populations are not accurately known, but appear stable worldwide, and they are not considered threatened.