Fig. 3. (A–F) Representative profiles of the lower jaw kinematics (thick, upper trace), sternohyoideus fascicle strain (middle trace) and EMG signal (thin, lower trace) are depicted. Lower jaw displacement and fascicle strain were normalized by subtracting by the minimum crystal distance and dividing by the maximum gape distance or resting fascicle length (FL) for a preparation. The drop line indicates the end of fast lower jaw depression, which is defined in this study as peak gape. The timing of fascicle strain and kinematics were closely matched within each strike, but there is variability in the strain profile and in the relationship between activation and strain. (A), (C) and (D) show a `notch' during fast lower jaw depression indicating slight lengthening. Each strike is from a different fish with the exception of (C) and (D),which are from the same fish. l, FL at each sampling time; l₀, resting FL; (l–l₀)/l₀=normalised strain. See Materials and methods for details.