Food segregation in three species of portunid crabs

Abstract

Gastric mills of 2,619 specimens of portunid crabs(Portunus pelagicus, P. sanguinolentus andCharybdis feriatus) in Tolo Harbour, Hong Kongwere examined. Of these, 1,498 containedrecognizable food items. A total of 34 food items wereidentified, 10 of which (29.4%) were common to thethree crab species. The principal food items werebivalves, decapods, fish and algae. However, thepercent frequency of occurrence of these food itemsdiffered significantly (ANOVA, p < 0.001) among thecrabs. In addition to these principalfood items, differences were noted in other dietarycategories: P. pelagicusand P. sanguinolentus fed on the brittle starOphiura kinbergi, whereas P.sanguinolentus and C. feriatus fed on detritusand gastropods. The diet of P. sanguinolentuswas found to be more similar to C. feriatus thanto P. pelagicus. Exploitation of different fooditems and selective feeding on common prey may reduceinter-specific competition for natural food resourcesand allow the three portunid crabs to co-exist in thesame habitat.