Project Summary

   A global collection of the deep-sea Aplacophora comprising some 20,000 specimens from about 60 surveys and expeditions will be monographed and a relational database developed along with keys, images, and short descriptions will be made available on the Internet. The Aplacophora are one of the seven extant classes of the Phylum Mollusca. Aplacophorans are vermiform and spicule-bearing. There are about 300 described species. Measurements, hard-part morphologies (epidermal spicules, copulatory spicules, and dissected radulae), and body shape as well as internal anatomy are utilized to describe the species.

 The aplacophorans are mollusks of broad phylogenetic interest. They can define questions about the position of Mollusca within the metazoan Bilateria and indicate an evolutionary relationship between sclerite-bearing early Cambrian fossil forms (e.g. Wiwaxia). Within the Class Aplacophora itself lie tests of the hypothesis that they are progenetic. Cladistic analyses of both morphology and DNA are being used to clarify phylogenetic relationships among the Aplacophora and to understanding the evolution of structures both within the Class and within the Phylum.

 The aplacophorans are an important part of the deep-sea benthos. In some localities certain species are numerically dominant. The Aplacophora have been hypothesized to be ancient, pre-Tethyan deep-sea forms, an idea to be tested through considering their present-day distributions as vicariant events. The tests may be applicable to other primarily deep-sea groups.

 The deep sea below 2,000 m is presently being used for ocean dumping of harbor dredgings. It is important to know the benthic fauna if the effects of such dumping on biogeochemical pathways are to be understood.

 This study will describe important species of deep-sea mollusks and make available identifications in to those interested in deep-sea benthos. The results of this research should add to the concepts of deep-sea ecology and metazoan phylogeny, as well as adding to the estimated 10-7 species of deep-sea benthic organisms still largely uncollected and unknown.

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