Movie 1.

Ex vivo, the heart of the electric catfish does not tolerate high electric currents. Representative videos of perfused hearts of a goldfish and an electric catfish with their corresponding atrial and ventricular recordings show the impact of electrical burst stimulations (900 pulses at 300 Hz). The hearts of electric catfish were equally sensitive as those of the goldfish. The yellow warning signs illustrate the timing of the electric shocks. Videos are shown at normal speed.