Fish 'see' in the dark using electric sensors

SCIENTISTS HAVE discovered that some fish can use electric fields to detect their prey in total darkness - a finding that raises the possibility of developing a device to locate objects in murky water.

Elephant fish, which generate weak electric fields, use electricity to judge the distances of nearby objects as accurately as if they had binocular vision. The fish, which have elongated lower jaws which looks like an elephant's trunk, live a nocturnal existence in freshwater African streams and find their way around almost exclusively with the help of the electric fields generated by an organ in their tails.

Gerhard von der Emde, a zoologist at Bonn University, said experiments on three captive fish that were trained to detect objects in a tank have shown how the electric fields can build up a three-dimensional picture of surroundings. "We've shown for the first time that the elephant fish not only detect objects by their electric receptors, but can measure distances just like we do with our two eyes," Dr von der Emde said in the journal Nature.

He said the results of the experiment confirm how the fish "see" distances in the dark. He is now working on a prototype device that mimics this biological mechanism. "The technical implication is that we can now reconstruct artificial sensors for detecting objects in dirty water. We should have underwater imagery without the need of a light if we can get sensors to do what fish can do," Dr von der Emde said.