(a) Time resolved speed plot showing the flow speed during the recovery and power stroke of actively feeding B. crenatus in quiescent water. The barnacle is viewed from the side (xz plane). Vectors indicate the direction of the flow. The water is accelerated forward (towards the right in the plot) during the power stroke with maximum local flow speeds at 15 mm s-1. (b) Vector plot overlaid on the images of the barnacle to show the position and movement of the cirri as they relate to the flow fields. The subplots a and b are synchronized and played back at 0.25 x actual speed for easier interpretation.