Molluscs then and now

Pelecypods, bivalve molluscs, also known as bivalvia, can be subdivided into orders and suborders on basis of shell structure,  hinge teeth, and type of gills.  Those included in the Prionodesmata have shells that are prismatic and nacreous. Mantle lobes are separate, siphons poorly developed, hinge teeth lacking or unspecialized. Those included in the Teleodesmata have shells that are porcelaneous and in part nacreous. Mantle lobes are generally connected, siphons well developed, hinge teeth specialized. Gills, which help determine suborder, may be  protobranch, filibranch, eulamellibranch or septabranch, going from the simplest and most primitive to the most advanced and evolved. Orders are determined largely on the basis of dentition, that is hinge teeth. Order with included suborders are: Taxodonta: hinge teeth numerous, subequal, and small.  Includes the Nuculacea which have protobranch gills and the Arcacea which have fillibranch gills. Schizodonta:...

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 tha...

To start off, there are two types of octopods, which have little in common other than the fact that they are both coleoid cephalopods, (those without an external shell), are exclusively marine, and have eight arms with suckers. Cirrate octopods have a single row of suckers on each arm and finger-like projecions, cirri, projecting on either side. Incirrate octopods, what most of us probably envision when we think of an octopus, have a double row of suckers on each arm and no cirri. Cirrate octopods have fins and webbing between the arms, incirrate have neither. Vampiroteuthis infernalis , the only kind of vampiroteuthid so far known, has much in common with cirrate octopods, and little with the incirrate or any of the decapods (squid, cuttlefish, and the like) -- other than what comes from being a cephalopod.  Vampiroteuthis has eight arms, each with a single row of suckers and cirri along either side, webbing between the arms and fins.  Also neither Vampiroteuthis nor cirrat...

Hi, This starts the blog Molluscs then and now, which continues from the long neglected Cepha-blog.  However this new blog will include all, or most all of the Mollusca, not only cephalopods but gastropods and pelecypods (Bivlavia) as well. Some of the information to be presented over time will come from online research, other from having worked in the collections of the New Mexico Museum of Natural History and Science, and still other from a collection of seashells from the Pacific island of Tutuila, American Samoa, collected by my parents while there in 1941 and '42. I intend on covering relevant items of interest, at least of interest to me, and maybe you. Some of it will have to do simply with the shells, leaving the animal that created it to inference. Other will delve into the animal itself, its physiology, life cycle, range and habitat. Coming  up, Vampiroteuthis, which is not what you may have been told.