Fig. 6. Response to differently sized colored obstacles by C. bronzie. The thickness of the histogram bars follows the width of the obstacles. Again, the wide obstacles provoked the strongest responses (A–C). Only a weak response was seen when the medusae were presented with thin obstacles and the medusae spent up to 31% of the time in contact with them (blue bar in B). The thin obstacles evoked a total of only eight avoidances (C). When mean distance for avoidance is transformed into visual angles similar values are seen across obstacle size (D). There is some more variation in the visual angles but this is probably due to the very low value for N (1 or 3) for the thin obstacles. N=10 for wide obstacles and 6 for thin obstacles, unless shown otherwise in the bars (repeats in A and B; recorded events in C and D). Values are means and error bars indicate s.e.m. ^*Significant difference at the 0.10 level from t-test, ^**significant differences at the 0.05 level.