Bivalvia or Pelecypoda

I'd say either Bivalvia or Pelecypoda is acceptable although Bivalvia is now the much preferred term for mollucs with left and right, dorsally hinged shells. Not meaning to be disagreeable, and perhaps because it's what I learned sometime back studying paleontology,  I prefer Pelecypoda, which had been used and well understood for some time.

Bivalvia, like Polyplacophora and Monoplacophora, has to do with skeletal features; in the case of Bivalvia with the pair of hinged shell coverings protecting the animal. Pelecypoda on the other hand has to do with the animal itself that produced the bivalves. Bivalvia is basically a conchologic term whereas Pelecypoda is essentially  a malacological term.

 One of the problems with the term Bivalvia, - no we're not going to get rid of it, it's too well entrenched - is that bivalves are not limited to molluscs. True, the term bivalve most generally does refer to bivalve molluscs. However there are other invertebrate organisms that are bivalved as well -- brachiopods, ostrocodes, conchostracans.  Remember there is a distinction between Bivalvia as a taxonomic term and bivalve as a vernacular descriptive term.

So to put it simply, Bivalvia are pelecypods.

Pending:  Pelecypod taxonomies.








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