Natural diet of the crab Notomithrax ursus (Brachyura: Majidae) at Oaro, South Island, New Zealand

Abstract

Foregut contents were examined of 724 Notomithrax ursus from the intertidal zone at Oaro, South Island, New Zealand. Of these, 659 contained food in their foreguts. Algae were the most common dietary component, occurring in the foreguts of 96.8% of the crabs examined. Small gastropods, isopods, amphipods, and decapods were also common in the foreguts examined. Other types of food eaten included bryozoans, polychaetes, sponges, ostracods, nemerteans, copepods, and bivalves. Although feeding on similar food materials, significant differences in dietary composition were evident for crab size and sex. Observations made on N.ursus in the laboratory revealed that N.ursus employed different techniques to feed on a range of other intertidal animals.