Archerd Shell Collection> Shell Classes > Buccinum undatum Opening a Clam
The drawings at the left show a whelk devouring a cockle. The whelk has come up on the back side of the cockle and places its foot firmly against the cockle shell. Then after using its tentacle tip to find the opening, it forces the anterior lip of its shell into the clam sufficiently to insert its proboscis and begin eating.
Similarly aggressive feeding tactics are also exhibited by some Thaiid molluscs of the Muricidae family.
A whelk can insert its proboscis in an opening as small as 1.3 millimeters and still devour its prey. Nielsen further reports that Buccinum whelks 2 inches long completely emptied out cockles about 1 inch long in 10-20 minutes.
The force of wedging is sufficient to sometimes break the shell, either of the whelk or its prey.
(Reproduced by permission of the Marine Biological Laboratory, University of Copenhagen; drawing of C. Nielsen,
"Observations on Buccinum undatum attacking bivalves and on prey responses, with a short review on attack methods of other prosobranchs,"
Ophelia 13:87-108, 1975.)
Archerd Shell Collection> Shell Classes > Buccinum Opening a Clam