Home Acknowledgments Conventions Glossary Maps References Links Articles Thumbnails Species list Next order	Acteonoidea In most sources the families in the order Acteonoidea are listed as part of the Cephalaspidea. However, recent DNA work (Malaquias, et. al., 2009) supports placing them in their own order. Alternatively, some sources place them within the Acteonimorpha (along with the Rissoellidae). Like the Cephalaspidea, they have a flattened cephalic shield, presumably evolved for burrowing. Unlike the Cephalaspidea, the shell is always well developed and external. Most are burrowers and nocturnal. They are carnivores, generally specializing in polychaete worms. At least three families are found in Hawaii. The genus Ringicula (family Ringiculidae) is mentioned only in the introductory material in Kay, 1979 as part of the molluscan assemblage found at depths over 200 m. However, it is not covered in the text nor do we have any other information indicating that it's been recorded from Hawaii. Some sources place the Ringiculidae outside the Acteonimorpha but in the Euthyneura. Some authors place these families in the lower Heterobranchia rather than the Opisthobranchia. Acteonidae Bullinidae Aplustridae
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