Scientists would like to build robotic submarines that can be used in complex tight spaces such as coral reefs, wrecks, oil rigs etc. The problem is that to avoid crashing in these circumstances you need to be able to see objects coming at you from all directions.
Malcolm Maclver and collegues at North Western University in Chicago have been inspired by weakly electric fish. These are a group of fish that live mostly in Africa and S. America which have a sixth sense. They are able to act a bit like a battery by passing current through the water around them, and they can then sense the voltage produced by this current with sensors in their skin. If there is something in the water which is either more or less conductive than the water, it will alter how the currents flow through the water and therefore alter the voltages sensed by the fish's skin. From these signals the fish will become aware of the object.
Malcolm has been building his own version and has sucessfully detected objects in water with only a few sensors. He hopes to use more in the future to study more complicated shapes and because the range is very limited he would like to use this sense on small agile mini-subs in the future.