Annelid Nervous Systems

Project Title: Structure and evolution of annelid nervous systems

Funding Source: University

Principle Investigator: Günter Purschke with Patrick Beckers & Thomas Bartolomaeus (Bonn), Conrad Helm (Göttingen), Katrine Worsaae (Copenhagen), Hannah Schmidbaur & Gerald Steiner, (Vienna)

Investigations on evolution, systematics, phylogeny and functional morphology are in the focus of interest. Currently these investigations are carried out on annelids, the segmented worms, and those taxa which are presumed to be closely related to them. Special emphasis is laid to the phylogenetic relationships within and validity of Lophotrochozoa.

Traditionally the annelid nervous system is described as consisting of a segmented, ganglionic ventral nerve cord with paired connectives and a prostomial dorsal brain in sub-epithelial position inside the body cavity. However, evidence is increasing that the last common ancestor of annelids possessed a much simpler nervous system comprising medullary cords in a basiepithelial position and a simple ring-shaped brain. Most likely a ganglionic rope-ladder-like nervous system including a more complex brain with several morphologically distinct types of neurons evolved later in annelid evolutionary history. Current investigations are related to the question of how the structure of the annelid nervous system looked like in the annelid stem species and the diversity and evolutionary history within several annelid clades.