Observations on Buccinum Undatum L. attacking bivalves and on prey responses, with a short review on attack methods of other prosobranchs

Abstract

The whelk, Buccinum undatum tries to attack all bivalves in the same way: It orients itself so that the front edge of the foot lies in contact with the edge of the valves of the prey; when the bivalve opens, the whelk suddenly inserts its lip between the valves thus preventing their closing. Buccinum may introduce its proboscis through the narrow slit or the valves may in some cases be wedged further open. Cardium edule is quickly devoured by this technique but a number of other cardiids as well as Nuculana pernula, Venus ovata, Spisula subtruncata and S. elliptica leap away when attacked. Pectinids swim away when touched by the foot of Buccinum. Species such as Mytilus edulis, Modiolus modiolus, Astarte montagui, Arctica islandica, and Venus striatula keep closed so long that Buccinum usually gives up and crawls away. Mya arenaria is buried so deep that it cannot be reached by the whelk. Stomach contents of specimens from the Øresund show a high occurrence of Modiolus, but it is concluded that the whelk mainly takes weak or dead bivalves. The flight responses elicited by Buccinum are identical to those elicited by Natica, Asterias and Astropecten and by adverse abiotic factors, such as an unsuitable substratum.