Swimming patterns and pharmacological effects in the larva of the ascidian Ciona intestinalis. (A) Montage of images from high speed video of swimming at 6 ms intervals showing alternating swimming movements and larval progression (in the last frame the final position overlays the first position (grey). Sequence runs from left to right and top to bottom. Scale bar in frame 13, 100 μm. (B) Traces showing strict left/right (L/R) alternation of tail movements during swimming strokes in a tethered decapitated larva in 1 mM L-glutamate. (C) Phase relation of the autocorrelation on the left side (blue) with the cross correlation (red) between left and right sides. (D) The same larvae showing loss of strict L/R alternation in the presence of strychnine. (E) Phase relation from the same larvae as in (C) showing a strong autocorrelation on the left side and no positive correlation with the right side (red) in the presence of strychnine.