Learning and the role of cue reinforcement in the shell cracking behaviour of the shore crab: carcinus maenas (L).

The shell-cracking behaviour of Carcinus maenas as it fed on Littorina littorea has been described. Of the various behavioural tactics employed, sawing, drilling/prizing, cutting/crushing and poking were found to be most frequently used. The establishment of a puncture or crack on the winkle shell while harvesting the prey served as an additional cue landing to (1) higher shell-cracking activity per unit time and (2) more frequent and directional inter change or behavioural tactics. Analyses of activity bouts; both on long duration basis (> 10s) and acts transition analyses showed that C. maenas shell-cracking behaviour is basically repetitive, with the effects of learning showing in the efficient utilisation of encounter time rather than in the development of new techniques.