## Measured and theoretical vibration frequency values pooled across subjects for each species group.

Overall range, mean, and SE of the measured peak frequency and calculated theoretical frequency for all vibrissae sampled. Measured values were obtained from laser vibrometer recordings and theoretical values are based on the Reynolds number calculation for a cylinder with a circular cross-section and matching stream-wise diameter. The percent difference between the absolute value of the measured and theoretical frequency was calculated for each vibrissa. The “% difference” column is the mean of the percent differences pooled across subjects for the specified species and angle of orientation. Samples that had dropped values at the 90° orientation due to poor laser vibrometer signal were removed from the data set. The resulting sample size was n = 9 at 0°, n = 9 at 45°, and n = 8 at 90° for California sea lions; n = 8 at 0°, n = 8 at 45°, and n = 8 at 90° for elephant seals; and n = 9 at 0°, n = 9 at 45°, and n = 6 at 90° for harbor seals.