Biophysical Methods In Ctenophore Physiology, Or Tentacular Spectacular: A Jellyfishertation

• Main Author: Townsend, James Presley
• Other Authors: Alison M. Sweeney, Kim A. Sharp
• Format: Thesis
• Language: English
• Published: 2018
• Subjects: adhesion; colloblast; ctenophore; pleurobrachia; taxonomy; Biology; Physiology; Zoology; Northwest Atlantic
• Online Access: https://repository.upenn.edu/handle/20.500.14332/29692; https://hdl.handle.net/20.500.14332/29692

Ctenophores are a group of gelatinous marine invertebrates found throughout the world’s oceans. Long recognized for their varied and dazzling forms, ctenophores have recently been at the center of a debate about the origins of animal multicellularity. Several recent phylogenomic analyses of early-diverging animal phyla (a group comprised of ctenophores, sponges, cnidarians, and placozoans) suggest that ctenophores are sister to all other animal groups, while others suggest that this result is a methodological artifact. However, these taxonomic discussions are hindered by pervasive gaps in our understanding of ctenophore physiology. Ctenophores are fragile animals that have historically been difficult to culture or study, but renewed interest in early animal evolution has sparked a revisiting of old questions in the biology of this understudied phylum. Here, I report the results of several such investigations. Throughout, I have employed a variety of novel adaptations of established biophysical techniques for use with ctenophores to better approach several longstanding questions about their physiology. First, a pair of investigations of the biochemical and mechanical properties of the colloblast, a cell type involved in adhesive prey capture that is unique to ctenophores. By utilizing a combination of confocal microspectroflourimetry and traditional histological techniques, I offer evidence that colloblast adhesive contains catechols incorporated into proteins, reminiscent of several other marine adhesive systems. Adapting a system for measuring surface tension, I have helped to measure the strength of colloblast adhesive, and developed a model of ctenophore prey capture based on the subsequent finding that it is surprisingly weak. Finally, I note a new species of ctenophore, captured in the deep waters of the northwest Atlantic Ocean, and discuss its description and classification by modern sequence-based methods, as well as the state of “ctenophorology” going forward. Doctor of Philosophy (PhD)