Saltmarsh periwinkles on Spartina

Saltmarsh periwinkles (Littoraria irrorata [Say]) on standing dead parts of shoots of smooth cordgrass, Spartina alterniflora. The University of Georgia Marine Institute in the background. The snails climb the shoots during any type of wetting phenomenon, including dew, as in this slide. The density of snails seen in this slide is not uncommon in Georgia marshes: hundreds per square meter. The snails rasp away portions of the dead shoot, selecting portions most rich in fungal mass. Naturally decaying cordgrass shoots appear to be the principal food of this snail. It is not yet clear whether the snails are primarily competitors with fungi for the dead shoot material, or whether the relationship is primarily mutualistic. The result of the snails' rasping activity is that the dead leaves are shredded into long tangled fibers and converted into snail fecal pellets. Photo from old ASLO slide collection; taken by S. Newell; background information provided S. Newell; scanned by K.L. Schulz.