Hammer Head shark

  There are eight different species of Hammerhead shark. All the species have the remarkable projections on both sides of the head, which probably is they reason why these sharks can detect electronic signals of no more than half a billionth of a volt. The head is probably used during electrolocation. By separating the receptors, the Hammerhead shark can receive signals in stereo. The oddly shaped head also seem to act as a wing that the Hammerhead shark uses for close-quarters maneuverability. The head looks somewhat like a flattened hammer, which is the reason behind the name of the Hammerhead shark. The nostrils and eyes are located at the tip of the extensions. All Hammerhead shark species have proportionately small mouths. The size of the eight different Hammerhead sharks varies between 2 and 6 meters. The largest Hammerhead species, the Great Hammerhead shark, will typically weigh around 230 kg (500 pounds) but can reach a weight of 450 kg (1,000 pounds). Three Hammerhead species can be dangerous to humans: the Great Hammerhead shark, the Scalloped Hammerhead shark and the Smooth Hammerhead sharks.

The strangely shaped head of the Hammerhead shark has given raise to a lot of speculation. 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. The entire head is equipped with sensors, and might be hammer-shaped in order to provide a larger area for the sensors. A larger sensor area would give the Hammerhead shark an advantage when it scans the bottom of the sea for food.

The Hammerhead sharks are probably related to the Carcharhinid sharks which evolved during the mid-tertiary period. It is somewhat difficult to investigate the evolutionary process of sharks, since the bones of sharks aren’t mineralized and seldom fossilize. There teeth are however often found as fossils. The teeth of the Hammerhead sharks are very similar to fossilized teeth from the Carcharhinid sharks. The Hammerhead sharks most likely developed during the late Eocene, Oligocene or early Miocene. It is hard to establish the exact era since it is difficult to know which teeth belong to Hammerhead sharks and which belong to Carcharhinid sharks.

All the Hammerhead shark species belong to the order of Carcharhiniformes, which means that they are ground sharks with one anal fin and two dorsal ones. They fins are spineless and the mouth is located behind the eyes. All Hammerhead sharks have five gill slits and a spiral intestinal valve. The spiral shape means that the food will pass through the intestines at a remarkably slow pace.