Meeting Abstract

P2.46  Friday, Jan. 4  Comparative functional morphology of trochid mantle cavities: To feed or not to feed VOLTZOW, J.*; IYENGAR, E.V.; Univ. of Scranton; Muhlenberg College voltzowj2@scranton.edu

Suspension feeding is a comparatively rare feeding mode within aquatic gastropods, although it has evolved independently several times. Molluscan gills have cilia that drive water over the gas exchange surface and other cilia that remove particles that become entrained in the mucus covering the gills. The additional energetic cost of using this gill to suspension feed should therefore be minimal. Alterations that permitted caenogastropod gills to collect food as well as to exchange gases probably involved minor evolutionary modifications of pre-existing ciliated tracts and other structures in the mantle cavity. Therefore, that so few caenogastropods are suspension-feeders is surprising. These snails should only need to divert mucus-entrained food to the mouth rather than to rejection tracts. As a member of the trochid family, Lirularia succincta is unusual in that it participates in suspension feeding as well as grazing. To examine suspension feeding in aquatic snails, we used histology, scanning electron microscopy, and video microscopy to compare the functional morphology of ctenidia and other mantle cavity features of Lirularia succincta with other trochids that do not suspension feed (Margarites pupillus, Calliostoma ligatum) and with other more distantly-related suspension-feeding gastropods.