Fall 2023

Document Type

Master's Thesis (Open Access)

Degree Name

Master of Science (M.S.)


Moss Landing Marine Laboratories


Gelatinous zooplankton are historically understudied, and we have much to learn about how they fit into the larger food web. Siphonophores are known to have widely varied diets and to select for a wide variety of prey. In this study I investigated siphonophore feeding habits in Monterey Bay, CA using a long-term remotely operated vehicle video dataset. In addition, I quantified the degree of specialization for each siphonophore-prey pair, and investigated the relationship between genetic distance and specialization differences. I found siphonophores tended to feed upon one prey group and in some cases fed exclusively on one species. Siphonophores also tended to select strongly for one type of prey. I found that more closely related siphonophores tended to show similar selectivity values, but the relationship was weak. Overall, this study upholds that siphonophores are specialists and very selective, and that phylogenetic distance has some positive relationship with selectivity. These findings uphold and expand our knowledge of the midwater food web, allowing us greater model specificity, the enhanced ability to track energy flow and carbon cycling, and greater capacity to manage the midwater ecosystem.