ABSTRACT
When it comes to ecologic and taxonomic diversity, gastropods have been the most successful group of molluscs. Except for the skies and glaciers they are found in practically all habitats. Their evolutionary flexibility is based on:
1. A muscular foot that was originally designed for sole-creeping, but has become variously modified for stick-walking (strombids), burrowing (naticids etc.), swimming (sea slugs, pteropods, heteropods);
2. An originally vegetarian radula, whose chitinous teeth could be transformed to serve as files, fangs, drills (Natica) or even as poison stings (Conus);
3. A wide mantle cavity transformable into a lung in terrestrial forms that manage to survive cold winters and dry desert seasons;
4. The concentration of mouth and sense organs into a retractable head.
