The Global Invertebrate Genomics Alliance (GIGA): Developing Community Resources to Study Diverse Invertebrate Genomes Supplemental Text

Porifera (sponges) are a diverse taxon of benthic aquatic (marine and limnic) animals, with over 8,500 described species distributed over four main extant lineages: Demospongiae (83 % of living species; demosponges, including bath sponges), Hexactinellida (glass sponges), Calcarea (calcareous sponges), and Homoscleromorpha (flesh sponges) (Van Soest et al. 2012) (Fig. 2). Traditionally, sponges were considered the sister group to the rest of Metazoa, and therefore of great significance for the reconstruction of early metazoan evolution. Sponges are now regarded to be monophyletic (reviewed in Wörheide et al. 2012), though further work is needed to unequivocally resolve their placement among the other non-bilaterian animals (i.e., those without bilateral symmetry) (Fig. 1). Although sponges are of great importance ecologically (as filter-feeders, bioeroders, and habitat formers), commercially (e.g., bath sponges) and pharmaceutically (as producers of bioactive secondary metabolites), their internal phylogeny and genomic diversity remains unresolved and understudied (Lavrov et al, 2008; Wörheide et al., 2012; Hill et al 2013). Comparative genomic approaches will not only shed light on the early evolution o