Size-selective predation and drillhole-site selectivity in Euspira fortunei (Gastropoda: Naticidae): implications for ecological and palaeoecological studies

Ontogenetic Shifts in the Predatory Habits of the Northern Moonsnail (Lunatia heros) on the Northwestern Atlantic Coast

“…Forensic-based studies of naticid foraging, including the current study, often rely on the presence of a robust relationship between moonsnail size and borehole diameter, such that predator size can be reliably inferred from drilled shell remains (e.g., Kitchell et al 1981, Dietl & Alexander 2000, Beal 2006, Chiba & Sato 2012. The laboratory results of the current study confirmed this relationship for Lunatia heros, demonstrating that larger moonsnails produced significantly larger boreholes than smaller moonsnails.…”

“…A strong relationship between OBD and predator shell length is typical of naticid gastropods (e.g., Kitchell et al 1981, Beal 2006, Chiba & Sato 2012. To assess this relationship for Lunatia heros, a laboratory-based study was undertaken to determine the size of boreholes drilled by predatory moonsnails of known shell lengths.…”

“…Although possibly true for large, deeply burrowed Mya arenaria, this seems unlikely for most prey items of Lunatia heros, particularly epifaunal gastropod prey. More likely, larger prey items are too big for small predators to handle and subdue (Dietl & Alexander 1995, Chiba & Sato 2012. Chiba and Sato (2012) have suggested that selective predation in Euspira fortunei (Reeve, 1855) may be driven by size limits of exploitable prey that accompany the size of the predatorÕs foot.…”

“…When size selectivity exists, larger predators tend to feed on larger prey items within a given prey species (''intraspecific size selectivity''; e.g., Rodrigues et al 1987, Kingsley-Smith et al 2003, Chiba & Sato 2012, with the correlation coefficient (R 2 ) of the relationship between predator size and prey size representing the strength of their selectivity (Dietl & Alexander 1997). Such selective predation may be driven by size limitations in the ability of smaller moonsnails to subdue and drill larger prey items (Berg 1975, Boggs et al 1984, Kelley 1991, Dietl & Alexander 1995, possibly related to the size of the predatorÕs foot relative to its prey (Russell-Hunter & Russell-Hunter 1968, Chiba & Sato 2012.…”

“…Such selective predation may be driven by size limitations in the ability of smaller moonsnails to subdue and drill larger prey items (Berg 1975, Boggs et al 1984, Kelley 1991, Dietl & Alexander 1995, possibly related to the size of the predatorÕs foot relative to its prey (Russell-Hunter & Russell-Hunter 1968, Chiba & Sato 2012. ''Interspecific prey selectivity'' has also been observed in naticid species associated with selection of prey species that, for a certain size class of prey and predator, offer a better energetic reward per unit handling time (e.g., Kitchell et al 1981, Kelley 1991, Dietl & Alexander 1995, Kelley & Hansen 1996.…”