Characteristics of Mollusca’s class-GASTROPODA

1)    They are marine, freshwater, terrestrial and few parasitic on echinoderms. 

2)    They have unsegmented, asymmetrical  body with a univalve, spirally coiled shell. 

3)    They have distinct head with tentacles, eyes and mouth. 

4)    They have foot which is ventral, broad, flat and muscular forming the creeping sole and often bearing dorsally a hard piece, the operculum on its posterior end. 

5)    They have visceral mass spirally coiled exhibiting torsion. 

6)    Mantle is a collar-like fold of body wall, lining the body whorl leaving a space, the mantle cavity ,between itself and the body. 

7)    They have Buccal cavity containing an odontophore with radula bearing rows of chitinous teeth. 

8)    They have digestive system consisting of a muscular pharynx, long oesophagus, stomach, long coiled intestine and anteriorly placed anus. 

9)    Most of them respire through gills(ctenidia ) ,some of them through the wall of the mantle cavity and many by lungs. 

10) They have open circulatory system with heart enclosed Pericardium

11) They have excretory organs  consisting of metanephridia which are paired in primitive forms and reduced to a single nephridia in most forms.
12)They have nervous system comprising of distinct cerebral and pleural besides buccal, pedal, parietal and visceral ganglia.

13)Most of them have sexes in two bodies(dioecious) but few have both the sexes in same body.

14) The development  includes trochophore and veliger larval stage.