Figure 7. Air movements detected by a hotwire anemometer, with the sensor 2 mm above the water surface, during lunges of the model frog. The vertical portion of the dashed line indicates the moment when the model began its acceleration. Gray lines show individual trials (N = 16). The solid red line shows the average of the air velocities during the first 0.1 s of a model attack. A 3rd order polynomial fit to this line constituted the air-borne signature of an attack (Eq. 1). The red arrow indicates the first time at which both the air velocity and its acceleration exceeded the values found to trigger escape behavior in similarly attacked cockroaches (Camhi et al., 1978).