ABSTRACT
Molluscs are the second largest animal phylum in terms of the global number of described species, and they have the largest known diversity of any marine group. We currently know about 82,000 valid described mollusc species (53,000 marine), with a yearly increment of about 580 new species descriptions (350 marine) (Bouchet 2006). Marine molluscs account for a quarter of all described marine biota. Gastropods make up roughly 85% of these and, specifically, the caenogastropods (comprising the vast majority of what people call “seashells”) account for around two-thirds of total marine molluscan diversity. Seashells have attracted the interest of naturalists, amateurs, and collectors since well before Linnaeus, and the result has been both a blessing and a curse for biodiversity exploration. This chapter is mainly concerned with the impediments of historical and current taxonomic practices in documenting marine shelled gastropod diversity, and exploring ways to move forward in view of the daunting diversity that remains to be described. Other groups of molluscs (e.g., marine slugs) and certainly several other phyla of marine invertebrates suffer from similar types of problems, and would probably also benefit from the solutions explored here.
