Diets of Portunus segnis (Forskål, 1775) (Decapoda, Portunidae) from the Persian Gulf, Iran

Abstract

Abstract The food habits of the blue swimming crab, Portunus segnis (Forskål, 1775) were investigated using specimens collected from trawl catches in the north-east of the Persian Gulf, from June 2018 to May 2019. Feeding habits of 304 adult female crabs, ranging from 2.6 to 8.7 cm in carapace length, were analysed. The stomach content of examined crabs showed to consist of crustaceans, fish, molluscs, unidentifiable material, sea grass and foraminiferans. We realized that the vacuity index did not show significant differences between ovigerous and non-ovigerous females (). Nevertheless, there was a significant difference in the vacuity index between barnacle-carrying crabs — Chelonibia testudinaria — and crabs without barnacles (). There was no significant difference observed in the quantity of the eaten foods between large and medium-sized groups of crabs. But a significant difference was observed between large- and small-sized crabs, and small- and medium-sized crabs. Moreover, significant differences were observed in food items between barnacle-carrying crabs and crabs without barnacles. Also, the percentage of empty stomachs was higher in ovigerous females than in non-ovigerous females.