The studies confirm an old hypothesis which theorized that molluscs are divided into two subphyla: the shell-bearing Conchifera and the spiny Aculifera. Although they lack a shell, squids belong to the shell-bearing Conchifera as do mussels and snails. On this subject, Professor Dr. Bernhard Lieb remarks that Nautilus (pearl boat), a 450 million year-old representative of the cephalopods, still bears a shell while in other representatives of this class the shell is either very much reduced in size or has been internalized. One unexpected result the researchers found was that snails (Gastropoda) and mussels (Bivalvia) are sister taxa. This is in contrast to the earlier assumption that snails and squids the groups with the most highly developed heads and "brains" are most closely related. This grouping of snails and mussels received little attention up to now, even though they make up over 95 percent of all mollusc species. Therefore, "we propose the node-based name PLEISTOMOLLUSCA, which includes the last common ancestor of Gastropoda and Bivalvia and all descendents," write the scientists in their publication featured in the scientific journal Nature.
The results are particularly interesting and of further scientific benefit because certain squids and the marine snail Aplysia californica are used as laboratory models for research into
|Contact: Dr. Bernhard Lieb|
Johannes Gutenberg Universitaet Mainz