The Medusozoa are a subphylum of the phylum Cnidaria including about 3800 species in three classes: Hydrozoa, Cubozoa, and Scyphozoa (Daly et al., 2007). Cnidarians emanated early in the history of metazoan evolution as exhibited by fossil evidence (Ausich and Babcock, 1998; Cartwright et al., 2007; Chen et al., 2002; Hagadorn and Waggoner, 2000; Han et al., 2010) and molecular phylogenies (Dunn et al., 2008; Peterson et al., 2004, 2008). Medusozoans enclose a variety of forms, containing ...