Figure 1 - Little skate, Raja erinacea, (left) and a sketch of its ampullary electroreceptor system (right). The electroreceptors are extremely sensitive and respond to potential differences of <1 µVolt. The skate's own ventilatory movements create electric fields as great as 10's of µVolts and these represent noise that can interfere with detection of important electric fields (e.g. those of prey) in the environment.