Molecular tools will be used to initiate an analysis of the early metazoan radiation as well as a thorough phylogenetic study of the Nematoda and Mollusca. Isozyme electrophoresis, restriction site analysis and sequence analysis of mitochondrial DNA will help to clarify the affiliations at the species and genus levels. Cytochrome c, globin and rRNA (DNA) sequences will be used for the phylogenetic reconstruction of higher taxa.