Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The hammerhead sharks are a group of sharks in the family Sphyrnidae, so named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a hammer shape called a cephalofoil. Most hammerhead species are placed in the genus Sphyrna; some authorities place the winghead shark in its own genus, Eusphyra. Many, not necessarily mutually exclusive, functions have been proposed for the cephalofoil, including sensory reception, maneuvering, and prey manipulation. Hammerheads are found worldwide in warmer waters along coastlines and continental shelves. The nine known species range from 0.9 to 6 m 3.0 to 20 ft long. All the species have a projection of their face on all sides of the head that gives it a resemblance to a flattened hammer. The hammer-like shape of the head was thought to help sharks find food, aiding inclose-quarters maneuverability and allowing the shark to turn sharply without losing stability. However, it was found that the unusual structure of its vertebrae allowed it to make the turns correctly, more often than its head.