PADILLA, D.K.; DILGER, E.K.; DITTMANN, D.E.: Phenotyic plasticity of feeding structures in species of Littorina

Several species of gastropods in the genus Lacuna, Family Littorinidae, have been found to have phenotypically plastic feeding morphologies. Animals fed different diets produce different shaped radular teeth. When fed diatom epiphytes found on eelgrass, snails produce blunt-shaped teeth. When fed macroalgae (kelps, ulvoids, or bladed red algae) they produce pointed-shaped teeth. Experiments were performed with three species of Littorina, with different development patterns, to see if they would respond in a similar fashion as Lacuna. Littorina littorea has plaktotrpohic development, Littorina obtusata lays benthic egg masses and has crawl away juveniles, and Littorina saxatilis is viviporous. We fed individuals of each species one of two diets, either diatom epiphytes or the green alga, Ulva lactuca, for 6 weeks and then examined their radulae. For each individual we deteremined the shape of the theeth on the anterior (older) portion of the radula and the posterior (younger) portion. Differences in tooth shape along the length of the radula of an individual was used to determine if tooth morphology was phenotypically plastic. We found that two species were phenotypically plastic, but the third was not. Of the two species that were plastic, only one showed a significantly different response to diet.