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. The squat-headed hammerhead (Sphyrna mokarran) and the scalloped hammerhead (Sphyrna lewini) are listed as endangered and the smalleye hammerhead (Sphyrna tudes) and the smooth hammerhead (Sphyrna zygaena) are listed as vulnerable on the IUCN Red List of Threatened Species.
Female hammerhead sharks give birth to their pups. They can have from 20-40 of them at any one time. They immediately separate themselves from the young though. Since these sharks have such a unique shape they are often feared in the water so they don’t have too many enemies. A good percentage of the young hammerheads will survive.