Fig. 6. Voluntary and manually induced sound pulses in Carapus boraborensis. Sonagram of 6 voluntary pulses (Ai) produced by a fish within a sea cucumber and 3 pulses (Aii) produced by 3 pulls on the sonic muscle of a fish with its sonic apparatus exposed. Oscillograms of a single pulse produced voluntarily (B) and by manual manipulation (C). Broken lines indicate termination of the pulse. The color ramp in A shows the scale of the relative dB, from white (lowest) to red (highest).