ABSTRACT
Annelids, or segmented worms, are a major group of Lophotrochozoa. They represent a large and ecologically important phylum. They show a huge diversity of body forms that coexist with various life history strategies. Most annelids belong to two main clades, Sedentaria and Errantia. Among the Errantia, the emerging model species Platynereis dumerilii has been at the forefront of developmental biology, evolution and ecology for two decades. This chapter presents (i) the basic biology of this model species, including its eventful life cycle synchronized with the natural moon phases, (ii) its anatomy showing dramatic changes following sexual maturation and (iii) the main steps of its development. This chapter also highlights the large panel of molecular and cellular tools recently developed to investigate diverse aspects of the biology of this species, as well as the numerous transcriptomic and genomic resources that have been established. Finally, while scientific topics developed using Platynereis dumerilii are diverse, this chapter focuses on two challenging questions that can be addressed using this species as model: What are the mechanisms controlling regeneration, and what is the importance of epigenetic regulations for gene expression regulation during development and regeneration in non-vertebrates?
