Fig. 4.

Larvae do not phototax on a shallow linear spatial gradient. (A) Irradiance map of the linear gradient lightscape. (B) Canton-S larvae navigational index, (v)/(s), computed for x and y directions on the linear gradient lightscape. n = 15 animals, 128 experiments. (C) (Left) Schematic of the linear gradient lightscape. Light is incident to plate at 90°. (Right) Probability of orientation vs. heading in runs for the linear gradient lightscape. The shaded area around the curve represents SEM. (D) Polar histograms of heading changes achieved by turns for a fixed initial run heading before turn. The arrow indicates the initial heading. (E) Probability of first head-sweep (h.s.) direction and head-sweep acceptance to left (L) and right (R) sorted by initial heading for linear gradient lightscape.