The cost of cleanerfish mimics to their models

Abstract

In aggressive mimicry, a ‘predatory’ species resembles a model that is harmless or beneficial to a third species, the ‘dupe’. Perhaps the most extraordinary case of aggressive mimicry occurs in Indo‐Pacific cleaning symbioses, where cleaner wrasses (the models) remove ectoparasites from larger fish clients. Several species of fangblennies mimic cleaners in behaviour and coloration. Instead of removing ectoparasites, however, fangblennies tear off fins, skin and scales from unsuspecting clients (the dupes). There is some debate over the extent to which cleanerfish mimics are really mimics because in some populations, the contribution of fish tissue to fangblenny diet is limited. In this study, I examine the impact of the resemblance between bluestriped fangblennies (Plagiotremus rhinorhynchus) and its putative model, the juvenile bluestreak cleaner wrasse (Labroides dimidiatus), on the model's cleaning activity to test the theoretical prediction that mimics should decrease the fitness of their models. I show that the presence of a bluestripe fangblenny in the vicinity of cleaner wrasses results in significantly lower client visit rates and inspection times compared to cleaners without a fangblenny nearby, and discuss why cleaner wrasses tolerate mimics near cleaning stations.