What are the characteristics of a Mollusks?
-Soft body often protected by a hard calcium containing shell
-Bilateral symmetry with three distinct body zones
1) Head-foot, which contains both sensory and motor organs
2) Visceral mass, which contains the organs of digestion, excretion, and reproduction
3) Mantle: secretes the shell
-Open circulatory system
-Most have gills and nephridia