Drilling by buccinid gastropods of the genus Cominella in Australia

In laboratory experiments, two buccinid gastropods, Cominella eburnea (Reeve, 1846) and Cominella tasmanica (Tenison Woods, 1876), abundant in lagoonal sediments in southwest Australia, exhibited identical ability to prey upon soft-sediment bivalves. Both buccinids killed and consumed live, apparently healthy, small 0-year-class Katelysia scalarina (Lamarck, 1818) (<1.8 cm in shell length), occasionally leaving behind drilled valves of this venerid. This represents the first record of shell drilling by a buccinid gastropod. Larger K. scalarina (3.1-3.8 cm) and large Katelysia rhytiphora Lamy, 1937 (3.9-4.6 cm) were not killed, even when their shells had chips along the margin. A third carnivorous gastropod, the muricid Bedeva paivae (Crosse, 1864), drilled and consumed Katelysia spp. in all three size-classes offered, but showed a preference for smaller individuals. Drill holes created by B. paivae on small K. scalarina could not be distinguished in shape or location from those left by the two buccinids. Consequently, these two members of the Buccinidae, along with B. paivae, probably contribute to the relatively intense rate of drilling mortality experienced by newly recruited Katelysia spp. in the lagoons of southwest Australia, but the results of these experiments do not confirm earlier suggestions that these two Cominella species kill larger bivalves.