Electroreception Essay, Research Paper

Nearly forty years ago, I observed sharks and rays respond to weak electric fields. The biological significance of this finding became evident when shortly thereafter

I discovered the common bioelectric fields in the vicinity of aquatic animals. The electric sense became an established fact when I proved that sharks and rays cue in

on the electric fields of prey, even during the dark or when the prey is hiding in the sand. Field strengths as low as 1-2 nV/cm suffice to alert them as to the presence

of prey. Furthermore, the motional electric fields of ocean streams inform sharks and rays about the flow of the water and the electric fields the animals themselves

induce by moving through the earth’s magnetic field provide them with the physical basis of their magnetic compass sense shown behaviorally.

The ampullae of Lorenzini, the elasmobranchs’ electroreceptors, feature an ingenious positive feedback mechanism amplifying the weak electrical input signal prior to

synaptic transmission. The system is founded on common biophysical principles applied in a unique fashion. Since the electrically excitable ion channels of the

receptor cells amplify the input signal without amplifying their intrinsic noise, optimal signal-to-noise ratios are achieved. These new findings not only help explain the

remarkable sensitivity of sharks and rays to naturally occurring electric fields, but also suggest brain processing mechanisms not yet recognized. Hence, the electric

sense of sharks and rays promises to provide new insights into the detection and processing of electrophysiological signals in animal and man.

Bibliography

bio ,i a 1999 ny