Sex differences in cleaning behaviour and diet of a Caribbean cleaning goby

Abstract

Male and female sharknose cleaning gobies Elacatinus evelynae (Gobiidae) occupying cleaning stations in monogamous pairs differed significantly in cleaning behaviour and diet. Females spent five times longer cleaning, took more bites from clients, engaged in more cleaning events on more client species, and cleaned at a higher rate than males. These behavioural differences tended to be reflected in the diet, with more females ingesting more client-gleaned items than males. These results are consistent with greater energetic requirements for reproduction for females. Male cleaning gobies were frequently absent from cleaning stations, presumably guarding eggs, and their presence at cleaning stations gave rise to foraging conflicts and interactions with females. The cleaning rate of females was significantly lowered by the presence of males, whether cleaning or not, whereas males cleaned for longer and took more bites when females were present. When cleaning the same client, males and females showed priority of first inspection, with females cleaning longer and taking more bites in cleaning events they initiated while males gained similar advantages in client- and male-initiated interactions. Furthermore, females initiated cleaning on larger clients, which may give them a foraging priority on a higher-quality resource since larger clients tend to have more ectoparasites. Finally, from a client's perspective, the cleaning service provided appears better in terms of length of inspection and bites taken when both males and females are at a cleaning station than when a single cleaner is present. However, the foraging differences and interactions between male and female cleaning gobies are of little consequence to clients since the cleaning service provided is simply reapportioned between males and females rather than changed by the interactions between gobies.