Optimal foraging and mucus-trail following in the carnivorous land snail Haplotrema concavum (Gastropoda: Pulmonata)

TitleOptimal foraging and mucus-trail following in the carnivorous land snail Haplotrema concavum (Gastropoda: Pulmonata)
Publication TypeJournal Article
Year of Publication1996
AuthorsPearce TAllen, Gaertner AM
JournalMalacological Review

We used seven characteristics of four species of snail to predict the rank preference that an optimally foraging Haplotrema concavum should show among the species. The overall predicted rank preference was Succinea ovalis juveniles, Zonitoides arboreus, Discus catskillensis, Strobilops labyrinthica. Six of the predictors gave ranks that were the same as or similar to the overall rank preferences: predicted rank preferences of larger prey aperture size (providing direct access instead of requiring drilling), greater prey body mass, and less feeding time on prey matched exactly, predicted preferences of greater prey shell size and greater percentage nitrogen of prey differed only in reversing the ranks of Z. arboreus and D. catskillensis, and the predicted preferences of thinner shells (requiring less drilling time if drilling is required) differed only in reversing the ranks of D. catskillensis and S. labyrinthica. In contrast, the predicted rank preference of slower prey speed was nearly opposite, suggesting that prey speed may not be a useful predictor of foraging choice for H. concavum. Similarities of predicted rank preference to observed rank preference as measured by feeding preference in pairwise feeding trials and by trail following index and trail coincidence index in mucus-trail following experiments are consistent with the hypothesis that Haplotrema concavum forages optimally. Observed feeding preference rank matched exactly the overall predicted rank preference. Observed trail following preferences matched predicted preferences in that Strobilops labyrinthica ranked least preferred in both measures of trail following, but some other ranks differed: Discus catskillensis ranked more preferred than Zonitoides arboreus in both following frequency and trail coincidence, and Succinea ovalis ranked highest in observed preference only in frequency of trail following, not in trail coincidence.