Fig. 9. Quantifying the colour changes of U. vomeris females in situ as a consequence of alternating exposure to dummy bird predation. (A,B) Two female U. vomeris were selected for each experiment (see Materials and methods and text for details). Circles are 30 min averages of numbers of pixels on the carapace of crabs with values higher than 200 (red, test animals subjected to dummy predation; blue, controls). Lines are regression lines through the data points. Stars mark the times of burrow closure. Note that crabs exposed to dummy predation tend become dull at a faster rate than control animals and can lose their bright colouration all together over a matter of days. See text for a full description of experiments.