Hammerhead shark:

Hammerhead shark, any of 10 shark species belonging to the genera Sphyrna (9 species) and Eusphyrna (1 species), characterized by a flattened hammer- or shovel-shaped head, or cephalofoil. The hammerhead sharks are a group of sharks that form the family Sphyrnidae, named for the unusual and distinctive form of their heads, which are flattened and laterally extended into a cephalofoil (a T-shape or "hammer"). Hammerhead Shark Profile The hammerhead shark is a group of species in the family Sphyrnidae. Most are in the genus Sphyrna, but one hammerhead shark has its own genus called Eusphyra. These deep-sea predators are one of the most recognizable species of shark due to their strange shaped head known as a cephalofoil. Hammerhead Shark Facts Overview The great hammerhead is the largest of the nine identified species of this shark. It can grow up to 20 feet in length and weigh up to 1,000 pounds, although smaller sizes are more common.