Evolution of larval development in marine gastropods

In this thesis I have investigated several aspects of the evolution of larval development in Caenogastropoda, the largest extant radiation of gastropod molluscs, probably also the largest radiation of extant marine invertebrates. Within marine invertebrates, the gastropods provide unique tools to perform studies on the evolution of larval development: important aspects of larval development are reflected in the morphology of their embryonic/larval shell, the protoconch, which is very often retained at the apex of the adult shell, allowing for inference on larval ecology of the organisms by the study of the adults, also fossil. This work is aimed at shedding light on two of the most controversial issues about larval development evolution: poecilogony and secondary reacquisition of planktotrophy.