Scientists have confirmed that cleaner gobies (Elacatinus) have evolved a pattern of blue and yellow stripes because it makes them the most visible to prospective clients.
The study by Liliana Lettieri and coauthors is published in a recent issue of the Journal of Experimental Biology.
Previous research has shown that both yellow and blue are potentially good signal colors in the tropical marine environment, so the authors tested the hypothesis that the blue stripes in Elacatinus gobies make them most conspicuous to a larger pool of potential clients.
They did this by first measuring the blue, yellow and green colours of Elacatinus gobies using spectrophotometry.
They then used colour opponent models of reef fish visual sensitivity to assess the likely contrast of these stripe colours against sponge and coral microhabitats.
Lastly, they modelled chromatic contrast through the eyes of the visual systems of numerous client species.
The authors found that blue provided the most contrast, i.e. is the most distinguishable to a larger pool of species against typical microhabitat backgrounds.
They infer that the evolution of blue stripes in Elacatinus gobies could be a result of natural selection for signals of high colour contrast, driven by the sensory biases and visual systems of diverse reef fish clients.
For more information, see the paper: Lettieri, L, KL Cheney, CH Mazel, D Boothe, NJ Marshall and JT Streelman (2009) Cleaner gobies evolve advertising stripes of higher contrast. Journal of Experimental Biology 212, pp. 2194"2203.