Fig. 2. Measurements of N. bachei body kinematics during fast swimming. Two sets of measurements from distinct swimming cycles from two different animals (black and grey circles) are presented to indicate the repeatability of the swimming motions. Maximum measurement uncertainty is ±6%. A curve fit to the data (solid black line) is used in subsequent analyses. (A) Velar diameter versus time during the swimming cycle. (B) Oral cavity volume versus time during the swimming cycle.