One sensory system that has not received much study is electroreception, the capability of some animals, particularly sharks and some electric fish, to detect extremely tiny electrical signals in the watery environment. This sense can be important in finding food, in species-specific communication, and in navigation. The receptor cells have extraordinary sensitivity to minuscule electrical signals, by mechanisms that have not yet been clarified. This project uses electrophysiological and optical recording techniques to examine how the ionic current channels across the cell membrane are activated in electroreceptor cells, and mathematical modeling techniques to make testable predictions about these biophysical properties. Results will have impact on how cells of a related type work in the lateral line organs of fish, and in the vertebrate inner ear. Understanding the high sensitivity of these cells will be useful in understanding other sensory systems in general, and perhaps relevant to claims about effects of weak electrical fields on biological tissue in general.