1) They are aquatic aniumals mostly found in sea and few in freshwater. Some are also terrestrial form.
2) The body consist of head, foot mantle and visceral mass.
3) They are soft bodied , unsegmentd ,bilaterally symmetrical animals.
4) The body is protected by an exoskeletoncalcareous shell produced by themselves.
5) They have open circulatory system .
6) They have respiratory system consisting of numerous gills or ctenidia provided with ospharadum at the base to breathe in water and lungs to breath on land.
7) They have excretory system consisting of a pair of metanephridia that open externally by nephridiopore.
8) They have nervous system consisting of paired cerebral. Pleural,pedal and visceral ganglia which are joined by longitudinal and transverse connectives and nerves.
9) They are usually unisexual but some are also hermaphrodite.
10)Fertilization is external or internal.
No comments:
Post a Comment