electro-sensitivity in sharks

The hammer head shark has to be the best looking of the sharks – I have only seen them on the “Blue planet” series – I was intrigued at the massive shoals where they seem to perform this odd twitch where the body flexes almost like a spasm – i was wandering if this has anything to do with generating a pulse of electricity that other sharks can detect? as thses sharks are not electrically active – but can only detect the electrical signals of muscle activity – such as small creatures under the sand….

“The ampullae of Lorenzini give the shark electrosense. The ampullae consist of small clusters of electrically sensitive receptor cells positioned under the skin in the shark’s head. These cells are connected to pores on the skin’s surface via small jelly-filled tubes. Scientists still don’t yet understand everything about these ampullary organs, but they do know the sensors let sharks “see” the weak electrical fields generated by living organisms. The range of electrosense seems to be fairly limited — a few feet in front of the shark’s nose — but this is enough to seek out fish and other prey hiding on the ocean floor.”

http://science.howstuffworks.com/shark2.htm