Figure 6.

Boxplots showing achromatic contrast (Michelson contrast) between mean iris and mean substrate radiance per substrate type. Data points (in red) represent processed, individual measurements. The achromatic contrasts are unitless (see Methods). Values above or below the gray horizontal strip (C = 0 +/‐ 0.018) indicate that a contrast is likely to be perceived by Tripterygion delaisi with positive values indicating irides being brighter than the substrate. The algal species covering the substrate are coded as follows: Cl, Chaetomorpha linum; Dl, Dictyota linearis; Hf, Halopteris filicina; Jr, Jania rubens; and Pf, Padina pavonia (see Table 1 for statistical significances and Appendix S1)