iNaturalist observations drastically expand knowledge of naticid predation in the northwest Atlantic

Comprehensive knowledge of predator diets is essential for studying predator-prey dynamics and understanding predation risk for species of economic importance and conservation concern. Globally, naticid gastropods (moonsnails) are major predators of marine molluscs; however, the diversity of their prey is often understudied. I revisited the diet of naticids in the northwest Atlantic by systematically analyzing >33,000 iNaturalist records of marine bivalves and gastropods, from northern Labrador, Canada, to southern Maine, USA, for naticid drillholes. I compared prey species detected using iNaturalist to an earlier study of Euspira heros (Say, 1822) diet to determine the utility of iNaturalist for documenting naticid prey diversity. iNaturalist captured 90% (17/19) of the previously-published diet for naticids in this region. Surprisingly, iNaturalist revealed an additional 13 bivalve and 11 gastropod prey species, more than doubling the previously-published diet breadth. While studies have attributed drillholes in this region to a single most-common species (E. heros), iNaturalist confirmed the presence of four additional naticids, with Euspira triseriata (Say, 1826) appearing common in the Minas Basin (upper Bay of Fundy, Canada). These results underscore the scientific utility of iNaturalist for studying naticid predator-prey ecology. This utility is not limited to naticids, but can be broadly applied to other predator-prey systems and ecological interactions.