Stimulation of latent enhanced propulsion in freely swimming jellyfish*

The external control of jellyfish swimming can potentially address basic science questions about animal-fluid interactions. To produce muscle contractions in free-swimming jellyfish, we use a wireless system of microelectronics embedded at the center of the animal, with electrodes embedded toward the bell margin. A symmetric two-electrode system is used to induce straight swimming downward in a 1.8-m vertical tank. Both experimental and model results show that we can enhance propulsion in freely swimming animals by increasing the external stimulation frequency above natural behavior, with a peak twofold increase in velocity. However, incomplete refilling of the subumbrellar volume at high frequencies can decrease swimming performance. By characterizing how the stimulation frequency affects swim velocity, this work constitutes an essential step toward user control of jellyfish locomotion for studies in basic science and engineering applications.