Fig. 4. At times when the paired fins are actively abducted during the Kármán gait, there is no appreciable axial muscle activity on either side of the body. Pectoral and pelvic fin silhouettes were digitized and enhanced to illustrate the pattern of abductions as the fish is buffeted from side to side by cylinder vortices. Open rectangles are aligned with the center of the cylinder, located approximately 1.5 L upstream (not shown). Scale bars are given for time (black, horizontal), muscle intensity (black, vertical) and the lateral amplitude of the center of mass (gray).