Behaviour of Carcinus maenas feeding on large Mytilus edulis. How do they assess the optimal diet?

Abstract

Shore crabs Carclnus rnaenas (L.) of 60 to 70 mm carapace width attacked mussels Myhlus edulis L. of 30 to 50 mm shell length by boring through the hinge or ventral umbonal region, but larger mussels could not be opened by this method. Withn the 30 to 50 mm size range, crabs preferred smaller mussels and appeared to exerclse their choice after handling prey of different sizes. When feeding on natural clumps of mussels, crabs consumed all encountered mussels small enough to be crushed (< 30mm) but also consumed some of the larger, less profitable mussels. This behaviour would result if the predator continually adjusts its estimate of prey availab~lities according to the last few items handled.