Evolution & Systematics

Gastropods are believed to have evolved from a monoplacophoran ancestor. This ancestor must have undergone torsion. The adaptive advantage of this torsion is unknown. This meant that the peak or umbo of the shell changed from being at the anterior end to the posterior end. The asymmetrical spiraling of the shell developed after this torsion, developing the modern day gastropod (Ruppert et al. 2004). In cowries, this coiling of the shell is obscured by the outer whorl of the shell and through the process of the shell thickening (Irie & Iwasa 2005).

The phylogeny of cowries is still undetermined with numerous variations of the taxonomic genera (Wilson & Gillett 1979). One fairly comprehensive database of cowrie phylogeny is the taxonomic table developed by the Cowrie Genetic Database Project of the Florida Museum of Natural History at http://www.flmnh.ufl.edu/cowries/taxon_list.htm (Meyer & Paulay 2005).