Developmental dynamics of gene expression in the penis worm Priapulus caudatus
Priapulus caudatus is a mud-dwelling marine predator best known as the penis worm. Priapulids have a key phylogenetic position in the animal tree of life. They belong to the Ecdysozoa – the animals that molt – together with the arthropods and nematode worms. We know in exceptional detail how flies and nematodes develop, but surprisingly little about the gene activity in the priapulid embryo, and how it compares to other ecdysozoans. Here we characterize the developmental dynamics of gene expression in P. caudatus using RNA-seq data, and compare to the gene activity in Drosophila melanogaster and Caenorhabditis elegans embryogenesis, to better understand the evolution of ecdysozoan development.