PREDATION OF COCKLES (CERASTODERMA EDULE) BY THE WHELK (BUCCINUM UNDATUM) UNDER LABORATORY CONDITIONS

摘要

The feeding rate and behaviour of whelks (Buccinum undatum] offered cockles (Cerastoderma edule) in laboratory experiments were examined. When presented with cockles in a range of sizes (10—40mm), 14 B. undatum (34.6—88.3 mm), held individually in aquaria, consumed a wide size range of cockles. Small whelks (<40 mm) consumed cockles (<23 mm), whereas large whelks, (>60 mm) ate a greater number of larger cockles (>30mm) and a wider size range of cockles (12-40 mm) than smaller whelks. The majority (90%) of the shells of the predated cockles were undamaged and the few (<10%) that were damaged showed only slight abrasions to the anterior and posterior shell margin. Filmed observations of B. undatum feeding on C. edule showed a method of attack that has not previously been reported and involved the use of the whelk's foot to asphyxiate the cockle or to pull the shell valves apart. No filmed evidence was found for the previously reported shell 'wedging' technique for prising open the closed shell valves of C. edule, although 10% of the shells of consumed cockles in feeding experiments had damaged shell margins.