Predation rate and prey preference by <i>Cercopagis pengoi</i> offered pigmented and unpigmented <i>Eurytemora affinis</i> in feeding trials (Experiments 1 and 2).

(A) predation rate (PR) in single-prey incubations (Experiment 1; mean ±SD; n = 12), and (B) prey preference index (Manley’s α) estimated from the mixed-prey incubations (Experiment 2; Tukey’s box and whisker plot, n = 12); the index ranges from 0 to 1, with higher values indicating greater preference. Shown are the median value (horizontal line), 25% to 75% response ranges (top and bottom lines of boxes) and minima and maxima (whiskers). Asterisk indicate a significant difference (p<0.05) in preference for the pigmented copepods when compared to those without visible pigmentation.