Gastropoda is the most speciose and diverse of the classes within Phylum Mollusca. There are approximately 60,000 extant species, comprising over 80% of the living molluscs. The gastropods are also one of the largest classes of animal; second only to Class Insecta in terms of species diversity. The gastropods were first classified as a cohesive group by Cuvier in 1797, who named the group "gastéropodes", Greek for stomach-foot, this was later replaced by the latin form "Gastropoda". Although the muscular foot is found in all gastropods, the group is actually defined by the presence of torsion, in which the body is twisted to one side during development. The earliest gastropods appeared in the Lower Cambrian and over 15,000 fossil species are known. Since then gastropods have colonised a wide variety of terrestrial, marine and freshwater habitats. As a result of their adapatation to several different environments, the Class exhibits a great diversity of body-plans and lifestyles.
Author: Jennifer Hoyal Cuthill
Last updated: 22.11.05
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