A note on edge drilling predation by naticid gastropods
Edge drilling is a strategy used by some gastropod predators when feeding on bivalve or brachiopod prey in which the borehole is positioned at the valve margin. This strategy can potentially reduce drilling times by a factor of two to three as compared with wall drilling (i.e. drilling near the thicker centre of the valve), the typical default drilling behaviour (Dietl & Herbert, 2005). Dietl, Herbert & Vermeij (2004) showed that, at least for muricid predators, edge drilling is expressed more frequently when drillers are exposed to intense competition risk. They speculated that the reduction in drilling time achieved by edge-drilling snails may be advantageous, allowing a predator to achieve either a higher net energy gain per unit time or reduced exposure to their own predators. There are few reports of edge-drilling behaviour by species of the gastropod family Naticidae, however, and the extent of its use across the family has never been investigated systematically, either in field studies or in experimental settings.