Trophic preferences and feeding morphology of two pulmonate snail species from a small New England pond, U.S.A.

Pseudosuccinea columella and Physa vernalis, the two dominant snail species inhabiting a small New England pond, are compared on the basis of trophic preferences and food gathering anatomy. While the composition of stomach contents of both pulmonates varied similarly over a year's time, significant differences were found between species. Pseudosuccinea individuals consumed relatively more filamentous algae and sand than did Physa, while Physa ingested a greater proportion of detritus. Pseudosuccinea appears to be omnivorous while Physa appears to be a detritivore. The jaws, radulae, and stomachs (crop-gizzards) of the two species differ markedly and are consistent with dietary differences.