Current insights into general animal biology, including immune function, are derived mostly from a few model organisms, a necessity imposed by effort required for in-depth studies. Modern next-generation sequencing (NGS) enables genomics-level investigations to test whether specific aspects of biology are general or unique across animal phylogeny. Meaningful comparisons require thorough identification of phylogenetically-relevant species. To provide a touchstone for Biomphalaria glabrata, a freshwater snail that is a major study model for invertebrate immunity, physid snails (Physidae; Hygrophila; Panpulmonata; Gastropoda; Mollusca) will be developed as a model for comparative immunogenomics. Chapter 1 introduces current research capabilities and details the rationale behind developing a physid as a comparative model for B. glabrata. Chapter 2, submitted as a manuscript to the Journal of Molluscan Studies, describes the molecular characterization that was performed for species identification and confirms taxonomic placement of physid snails relative to B. glabrata. Comparative mitogenomics revealed high levels of intraspecific sequence divergence between the entire mitochondrial genomes of the two P. acuta isolates, identified a unique gene order, and compared substitutions rates of gene sequences from the mitochondrial genomes of other gastropods. Additional materials are provided in the Appendices; Appendix A provides supplemental information for Chapter 2 and Appendix B provides a report of preliminary results from NGS-based gene discovery for initial characterization of the immune response of P. acuta to bacterial exposure toward comparative immunogenomics. Results from this thesis support continuing efforts to develop P. acuta as a comparative immunogenomic model to B. glabrata. Advisors/Committee Members: Adema, Dr. Coenraad M., Stricker, Dr. Stephen, Takacs-Vesbach, Dr. Cristina.