In 2019, scientists shook earthworms and found waves oscillating at half the driving frequency

Scientists observed earthworms developing body waves at half driving frequency. Their flexible, water-filled bodies and elastic skin supported these unusual oscillations. This phenomenon resembled waves found in vibrating liquid drops and phantom models. Researchers believe this could help probe biological processes like nerve impulse propagation. The findings suggest nonlinear wave excitation has potential beyond earthworm studies.