The Great Hammerhead Shark

  The great hammerhead shark is one of the world's largest sharks; and one of the most dangerous. Thirty three shark attacks have been attributed to it. These ferocious hunters can grow up to six metres long and they feed off stingrays, large fish and smaller sharks. They are opportunistic hunters and often feed on grey reef sharks after they have been exhausted through mating. In addition, they have cannibalistic tendencies.
  Great Hammerheads are found throughout the world in Temperate and Tropical waters. They are, however, badly endangered as their fins are very valuable ingredients for shark fin soup.
  The difference between a great hammerhead and the more common scalloped hammerhead, is the shape of the hammer (or cephalofoil, to use the scientific term). That of the great hammerhead is wider and lacks the dips which earn the scalloped hammerhead its name. The cephalofoil is used to detect electronic signals in the water, which are produced by its favourite prey: stingrays.

A close up of a scalloped hammerhead shark's cephalofoil.

A great hammerhead near Australia. Note the difference
of its cephalofoil to that of the scalloped hammerhead's.