Elasmobranch Scanner Tech Ready For War On Terror

The US Navy's plan to detect mines and other underwater objects by their electrical fields - in the same way as sharks and rays find prey - has moved closer to reality. Elasmobranch fish (rays, sharks and suchlike critters) have various senses, including relatively conventional vision and smell. But they also have slime-filled "canals" in their heads known as "the ampullae of Lorenzini," after the Florentine court doctor who documented them in 1678. (In seventeenth-century Florence, the ducal physician was apparently expected to dissect any sharks that happened to turn up.) The slime tubules, it later turned out, are effectively biological voltmeters with sensitivities as fine as a few microvolts. Sharks use them to detect the bioelectric fields of bottom-feeding flatfish lying concealed in sand or mud, so as to scoff them...