1. (used with a sing. verb) A theory that explains the global distribution of geological phenomena such as seismicity, volcanism, continental drift, and mountain building in terms of the formation, destruction, movement, and interaction of the earth's lithospheric plates. 2. (used with a sing. or pl. verb) The dynamics of plate movement.
Despite the fact that mollusks are very susceptible to changes in their environment because of their permeable skin and soft body (often with an exoskeleton in the form of a shell), they have adapted to all of the main environments of our planetâmarine, freshwater, and terrestrial. With 41% of the 736 documented extinctions of all animal species, the number of mollusks exceeds that of any other major taxonomic group 3. 2  Most documented endangered mollusk species are non marine (they live in freshwater or terrestrial environments) 5.
Limpets, mussels and barnacles on a rock in the intertidal zone. Gastropods, or univalves, are the largest and most successful class of molluscs. 60,000â75,000 known living species belong to it. Most of are marine, but many live in freshwater or on land. Their fossil record goes back to the later Cambrian. Slugs and snails, abalones, limpets, cowries, conches, top shells, whelks, and sea slugs are all gastropods. The gastropods are in origin sea-floor predators, though they did evolve into many other habitats. Many lines living today evolved in the ...