Meeting Abstract

35.3  Friday, Jan. 4  A 3D investigation of the morphology of lepetellid limpets (Lepetella sierrai): hypotheses on feeding ecology and symbiosis JUDGE, J. L.*; HASZPRUNAR, G.; UC Berkeley; Ludwig-Maximilians University Munich jennajudge@berkeley.edu

The Lepetelloidea, a clade of small limpet-shaped gastropods, represents a case study in continental margin and deep-sea diversification. Lineages in this clade have been found associated with various substrates, including hydrothermal vents, seeps, wood, whale bone, polychaete tubes, elasmobranch egg cases, seagrass rhizomes, algal holdfasts, crab carapaces, and sponges. It is unclear how each lineage utilizes its substrate; as a food source, a grazing surface, or a substrate that positions them in a reducing environment suitable for chemoautotrophic symbionts. Symbiosis is an obvious trait that would provide a lineage with a clear advantage in a nutrient-poor environment like the deep-sea, indicated by the prevalence of chemosymbiotic animals at hydrothermal vents. One lepetelloidean family, Lepetellidae, lives specifically on or inside empty polychaete tubes of the genus Hyalinoecia. The detailed morphology of a Mediterranean species, Lepetella sierrai, has been reconstructed from serial sections using the 3D modeling software AMIRA, and compared to other members of the genus. A unique alimentary tract, with huge oesophageal pouches, no true stomach, and an extensive multi-lobed midgut is shown. Additionally, a bacteriocyte system surrounding the entire mantle rim has been revealed via light microscopy and TEM. This is the first recognized evidence for microbial symbiosis in lepetelloidean limpets. A feeding ecology combining nutrition from the sugar phosphate polymer worm tube and chemoautotrophy is likely. Further investigation of this and other lepetelloidean feeding ecologies will contribute to revealing the drivers of evolutionary success in this limpet clade that lives on a high diversity of substrates utilized by few other lineages.