Fig. 4. Light and perceptual environments for Tadros. (A) Overhead view of light environment in experimental tank, with color gradient showing position of light source. Arrow indicates radial slice shown in B. (B) Light intensity gradient along radial indicated in A. (C) Perception of light gradient by Tadros. Polar plots indicate light intensity (along radii, with origin at 0 lux) registered by Tadros at different headings every 0.1 m along radial slice shown in B. A heading of 0° means that the Tadro was facing in the direction indicated by the arrow in A. Note eyespot is located 45° to the left of the Tadro's centerline (see Fig. 2).