Marine sponges interact and coexist with many different organisms. A two-sponge association between Amphimedon erina and Geodia gibberosa commonly occurs in the Florida Keys. Previous studies have only focused on the ecological influence of the association; they did not examine the cellular basis of the association. This association between A. erina and G. gibberosa was used in the development of an in vitro model to further the understanding of the cellular basis of natural sponge-sponge associations. In this study, sponge cells were cultured individually and in co-cultures and their responses related to apoptosis, cell death, and proliferation were monitored using high content imaging. Co-cultured cells of species that form sponge-sponge associations did not have the same cellular responses compared to co-cultured cells of species that do not form sponge-sponge associations. Protein expression analyses demonstrated that the model that was established does not mimic the cellular response of the association in nature, but this model can be used to test in vitro cellular interactions of sponge species that do not form associations in nature. In addition, the protein expression data that were obtained revealed that sponges use similar apoptotic pathways as humans and suggest that sponge cells may shut down cell cycling in order to repair damaged DNA. This research is a small piece to the puzzle that is sponge cell culture research. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Populations of a marine invertebrate symbiont were found on the outer surface and internal spaces of a keratose sponge from a shallow bay in the Florida Keys in May 2014. A total of 24 specimens of the seagrass and reef-dwelling sponge were collected between May 2014 and August 2015 to provide material to identify both host and symbiont, and elucidate information on the nature of the association. Based on a morphological analysis via light microscopy, histology, and scanning electron microscopy (SEM), and 99% similarity in aligned partial sequences from 28S and 18S nuclear ribosomal genes (rDNA), the symbiont was identified as the solitary entoproct Loxosomella vivipara Nielsen, 1966 (Entoprocta: Loxosomatidae). A partial sequence from the Internal Transcribed Spacer Region 2 (ITS2) of L. vivipara was registered to GenBank for the first time. The identity of the host sponge, based on a morphological investigation, is resolved as “velvet sponge” Hippospongia cf. gossypina Duchassing and Michelotti, 1864 (Demospongiae: Spongiidae). This is the first report of an entoproct commensal from Hippospongia cf. gossypina, a sponge that formerly had great commercial value when it was abundant throughout the Bahamas, Florida Keys and Gulf of Mexico. Other common sponge species at the study site were collected to investigate the host specificity of L. vivipara. Evidence that L. vivipara favorably selects the sponges Hippospongia cf. gossypina and Chondrilla nucula over other potential host sponges at the study site is provided. Commensalism is the most plausible justification for this relationship: L. vivipara is dependent on sponges for protection and food particles, while the sponges are unaffected by its presence. Further evidence of host-specific inquilinism is provided for L. vivipara associated with Hippospongia cf. gossypina, but not for L. vivipara associated with C. nucula. An inquilinistic association between an entoproct and sponge is a rare discovery only mentioned in one previous study. Sponge aquiferous qualities such as aperture and canal size, canal and choanocyte chamber arrangement, seawater pumping rate, and food particle size selection are likely factors that inhibit or enable inquilinism in sponge-entoproct associations – a potential topic for future researc / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection