Prey-Size Intake in Humbug Damselfish, Dascyllus aruanus (Pisces, Pomacentridae) Living Within Social Groups

SUMMARY (1) Field observations were made on the feeding behaviour of individuals amongst social groups of D. aruanus. The sizes of prey taken were investigated by the analysis of stomach contents. There was a clear relationship between the size of prey taken and the rank of an individual within its social group. On removal of the larger individuals from a social group, the smaller individuals began to take prey previously destined for the former. (2) These results are related to what is known from previous work about the movements of D. aruanus whilst feeding as a social group. It is concluded that the size of prey taken by D. aruanus is influenced by the social habit of this species. The relative position of an individual within its social group influences its subsequent prey intake.