The Chaetognath project

Our small research team at the Station Marine d’Endoume in Marseille focuses on the enigmatic phylum of chaetognaths. These organisms constitute one of the most astonishing group of animals because of their unique body organisation, mosaic morphological characters and peculiar way of development. Furthermore, the chaetognath bodyplan is strikingly conserved from the lower cambrian, the moment of the cambrian explosion when multicellular animals make their first appearance in fossil archive (to learn more, see the chaetognath page). 

Recent advances in phylogenomics allowed to point out the very original phylogenetic position of chaetognaths as a third protostome branch, most likely in a basal position in regard to classical lophotrochozoan and ecdysozoan clades. This has pointed out that many characters of chaetognath such as their development could be reminiscent of the bilaterian ancestor.

Our goal is thus to understand the origin of evolution of the chaetognath body plan through 3 main approaches:

1) Attempt to refine the branching of chaetognaths and the tree of animals using EST-based phylogenomic approach. 

2) Characterize the molecular actors that underline chaetognath development and body organization. We especially focus on the complex of Hox genes that are involved in anteroposterior differentiation. 

3) Understand the genomic bases of such a morphological conservation through study of gene duplication, transcription regulation and rates of molecular evolution in this phylum. 

Our project is hosted in the DIMAR lab at the seaside Station Marine d’Endoume located within the town of Marseille. We are affiliated to the Centre d’Océanologie de Marseille and the Université de la Méditerranée.