Relationships between snails, epiphyton, and macrophytes are widely studied because epiphytes decrease light for macrophytes, and snails may benefit the latter when they consume epiphytes. Thus, organic compounds released by macrophytes that attract snails could be an evolutionarily advantageous mechanism. This hypothesis was tested with three species of submerged macrophytes (natives: Egeria najas and Cabomba furcata; exotic: Hydrilla verticillata), which were maintained in microcosms in the presence of ancylid snails. However, the hypothesis of limpet attraction by macrophytes was rejected. Instead, epiphyton attached to E. najas attracted more snails than that attached to the other species. This attraction could be explained by chemical signals (organic compounds), released by certain species of algae that are detected by snails.