Fig. 4. Phase shift between the maximum contraction of the ventricle (arbitrarily set at 0°) and the branch point (open circles; BP in Fig. 1), the lateral venae cavae (grey circles; LVC in Fig. 1), the branchial hearts (black circles; BH in Fig. 1) and the efferent branchial vessels (hatched circles, EBV in Fig. 1). Time proceeds clockwise. Each concentric circumference shows the averaged data for one cuttlefish. NS indicates averages calculated from raw data that were not significantly similar (significance only determined if there were more than two data points. There were never more than four data points). Because data on the efferent branchial vessel and ventricle were not collected simultaneously, contraction phase of the efferent branchial vessel was calculated from its average phase shift from the average phase shift of the branch point. We obtained no data on the branchial heart for the cuttlefish of innermost circumference.