In addition to the five senses that humans possess, sharks also receive sensory input through electroreception, the ability to sense weak electric fields. Sharks not only sense these fields, they rely on them to locate prey and, perhaps, navigate through the ocean.
Sharks have the greatest sensitivity of any known marine animal to electric fields.
Special receptors located around the head and snout of a shark detect electric vibrations. This specialized system of gel-filled pores, called the ampullae of Lorenzini, allows the shark to detect the small electrical signals that all animals, including human beings, emit. This sense works best at close range and enables the shark to pinpoint an animal it may not even see in dark water. A shark also uses this sense to position its head and mouth when moving in for final attack. Scientists estimate the number of living shark species at more than 350.