........................................................................................................................................ ii Acknowledgments ....................................................................................................................... iv List of Figures ............................................................................................................................. vii Chapter 1: A Review of Bivalve Embryonic and Larval Life Stages with an Emphasis on Larval Nervous Systems ................................................................................................... 1 Significance of Bivalve Research ................................................................................... 4 Bivalve Embryonic and Larval Ontogeny ...................................................................... 8 Bivalve Adult Nervous Systems ................................................................................... 16 Bivalve Larval Nervous Systems .................................................................................. 17 Effect of the Nervous System on Settlement Behaviors ............................................... 25 Conclusions ................................................................................................................... 27 Chapter 2: Characterization of the Central Nervous System and Various Peripheral Innervations During Development of the Larval Oyster Crassostrea virginica ........... 30 Introduction ................................................................................................................... 34 Materials and Methods .................................................................................................. 36 Results ........................................................................................................................... 38 Discussion ..................................................................................................................... 77 Chapter 3:The Presence and Location of Small Cardioactive-like Peptides (SCPs) in Larval Crassostrea virginica and Newly Hatched Berghia verrucicornis ..................... 85 Introduction ................................................................................................................... 89 Material and Methods ................................................................................................... 91