Natural Diet, Feeding and Predatory Activity of the Crabs Callinectes arcuatus and C. toxotes (Decapoda, Brachyura, Portunidae)

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Abstract
The natural diet of C. arcuatus Ordway in the Huizache-Caimanero lagoon system (western Mexico) was determined and several aspects of its feeding and predatory activity were investigated. Limited observations were also made on the diet of C. toxotes Ordway. The diets of the 2 crabs were similar but that of C. arcuatus appeared more varied; it consisted mainly of bivalve mollusks, crabs and fish. Differences in the diet of C. arcuatus in different areas of the lagoon system and at different times of the year reflected differences in prey availability rather than in prey selection. Small crabs (< 60 mm breadth) were basically detritivores and scavengers, while larger crabs were scavengers and predatory feeders. They were not major predators of penaeid shrimp and C. arcuatus was not an efficient predator of highly mobile animals such as shrimp. Feeding occurred mainly at night, especially around dusk.