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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.