The great hammerhead shark is the largest species of hammerhead sharks. Known scientifically as Sphyrna mokarran, it is one of nine kinds of sharks that all share the distinctly shaped head that sets them apart from other sharks and gives them the name hammerhead.
Found worldwide in tropical waters near coastlines, the great hammerhead can be sighted near beaches and is considered a potentially dangerous shark to humans. Adult sharks can reach a length of 10-15 feet in length and a weight of 300-500 pounds. The longest great hammerhead ever recorded was 20 feet long and the heaviest was 991 pounds. These sharks are usually found eating stingrays but will also take fish and shellfish in their diets.
The body design of a great hammerhead shark is typical of most sharks with the exception of its head. The head is a distinct hammer or mallet shape and the eyes are set at each end of the hammer. The nostrils are placed spread apart in the front of the head rather than close together as on a typical shark’s head. All sharks are equiped with sensory organs that enable them to locate prey. In the case of the hammerhead, these organs are much more concentrated at the front of the head where the hammer is widest. These sensory organs, known as ampullae of Lorenzini, allow sharks to pick up the electrical fields of prey in water that is too difficult to see through. Hammerhead sharks have a greater ability to locate prey due to their different head design. Stingrays, the great hammerhead’s favorite prey, hide under sand and are well camouflaged to the average obsever. Hammerheads are able to locate stingrays in hiding and then hold their struggling prey down with their heads while they eat.
Of the species of hammerheads, the other well known types include the scalloped hammerhead (Sphyrna lewini), the bonnethead hammerhead (Sphyrna tiburo), and the smooth hammerhead (Sphyrna zygaena). No other species of hammerhead comes close to the size and weight of the great hammerhead but each type has its own unique head shape. The scalloped’s head looks just as its name implies, the hammer has a scalloped look to it. The bonnethead is more unique in appearance as its eyes to not protrude as greatly as the great hammerhead and has a rounded appearance akin to a shark wearing a bonnet. The smooth hammerhead also has a rounded appearance but is only slight when compared to the more extreme roundness of the bonnethead.
Like all other sharks, great hammerheads are best left unprovoked. Although they are not known to have attacked humans as often as other shark species, it is still best to always use caution and avoid areas where there may be large concentrations of great hammerheads. All sharks, regardless of their species, possess very sharp teeth and will bite when defending themselves.
Sources:
http://marinebio.org/species.asp?id=87
http://www.flmnh.ufl.edu/fish/gallery/descript/greathammerhead/ghammerhead.html
http://animals.nationalgeographic.com/fish/hammerhead-shark/
