Hydrozoans are the most diverse class of cnidarians in terms of life cycle evolution and colonial complexity. My role in CnidToL is to intensively sample hydrozoan taxa, especially of the subclass Anthoathecata, for DNA sequencing and molecular phylogenetic analysis, in order to reconstruct the life history patterns and evolution of complex colonies. In addition, I intend to investigate the mechanisms underlying these patterns of evolution by performing comparative gene expression studies.