Polychaete sperm: phylogenetic and functional considerations

The terminology used to describe the sperm of aquatic animals is discussed. It is argued that the use of the terms 'primitive' and 'modified' sperm co nfuse functional associations between sperm morphology and reproductive mod e with perceived phylogenetic patterns. Therefore, terms describing sperm b ased on function should be preferred. This terminology is designed to avoid any a priori judgement of phylogenetic pattern. The various modes of sperm packaging and transfer in polychaetes are reviewed with regard to the morp hology of the sperm. An example using an explicit phylogenetic hypothesis o n the polychaete family Sabellidae is used to suggest ways to study the evo lution of sperm structure, and to assess functional associations between sp erm and reproductive mode.