von Dassow, George,,Bergen, Sebastian2022-07-122022-07-122022https://hdl.handle.net/1794/27264Long-standing tradition in larval biology has been to categorize invertebrate larval developmental strategies into two general modes: lecithotrophic versus planktotrophic development. Lecithotrophic larvae hatch from eggs containing all the nutritive materials required to form a juvenile, while planktotrophic larvae graze on unicellular algae as a requirement for metamorphosis into a juvenile. However, recent work, which includes studies on members of two large taxa of spiralian worms, polyclads and nemerteans, have revealed the widespread presence of larvae who consume animal prey instead of algae. We refer to this developmental mode as macrophagous carnivory. The intent of this thesis is to fully document larval development and prove that a carnivorous diet is required for the maturation of an unknown Capitellidae species found in the waters around Coos Bay. These larvae have a distinctive feeding behavior and morphologically develop on a solely carnivorous diet to settlement competency. These findings contribute to a growing body of evidence for macrophagous carnivory as a widespread larval strategy to extract resources from the plankton. Their developmental changes that occur from collection from plankton to post-settlement have been documented, though their identity was never uncovered, and their eggs and adult forms are current unknown, leaving their lifecycle incomplete.en-USCC BY-NC-ND 4.0LarvaDevelopmentCarnivoryPlanktonCapitellidaeThesis/Dissertation0000-0002-2201-9357