Mari-Anna D’Angelo
December 19th, 2012
Mr. Donahue

Hammerhead Shark

Hammerhead sharks are aggressive and smart hunters, feeding on smaller fish, octopuses, squid, and crustaceans. Stingrays seem to be a particular favorite of the great hammerhead. For hunting they use their oddly shaped heads to improve their ability to find prey. For instance, for killing a stingray it uses its "hammer" to pin the stingray down while it takes bites from the ray's wings. There are two main theories regarding its development. Some scientists believe that the shape evolved gradually over numerous generations, while others suggest that it was a sudden mutation that rapidly proved to be an advantage. All Hammerhead sharks belong to the genus Sphyrna. The danger to humans is not a high chance. They do not actively seek out human prey, but are very defensive and will attack when provoked. Three hammerhead species can be dangerous to humans: the Great Hammerhead shark, the Scalloped Hammerhead shark and the Smooth Hammerhead sharks. The setup of a hammerhead sharks head is very different. All Hammerhead shark species have proportionately small mouths. Their wide-set eyes give them a better visual range than most other sharks. And by spreading their highly specialized sensory organs over their wide, mallet-shaped head, they can more thoroughly scan the ocean for food. One group of sensory organs is the ampullae of Lorenzini, which allows sharks to detect the electrical fields created by prey animals and other things as well. The hammerhead's increased ampullae sensitivity allows it to find its favorite meal, stingrays. They love stingrays, which usually bury themselves under the sand. The great hammerhead shark feeds on a wide variety of prey, favoring stingrays, and also hunting down groupers and sea catfishes. It also feeds on squid, crabs, tarpon, sardines, toadfishes, porgies, grunts, jacks, herring, grouper, boxfish, other sharks, skates, guitarfish, cownose and eagle rays. The shark feeds mostly at dusk. 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 (450 kg).The 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. The great hammerhead is found in tropical and sub-tropical waters worldwide. The great hammerhead migrates seasonally to cooler waters during the summer. Found over the continental shelves, island terraces