Phylum Mollusca

General Characters:

•    Body

•      Soft bodied animals cover with calcareous shells

•      Unsegmented body.

                     

 

• ·   Body part

1.   Head

       Mouth

       Eyes

       Tentacles

       Sense organ

 2.   Foot

              Locomotion                    

              Creeping

3.    Mantle and visceral mass

               Space between main body and envelope

·       Aquatic

Mostly marine (coral 1)

Few fresh water (ghat 2)

                                                                                                            

                         1                                        2                        

•     Triploblastic

•     Bilateral symmetry

•      Body cavity is haemocoel

•      Digestive system is simple with mouth and anus.

•      Pharynx contain rasping organ radula.

•      Circulatory system is open except cephalopods.

•      Respiratory organs are gills and lungs.

•      Excretory system is metanephridia.

•      Nervous system consist of paired cerebral, pleural, pedal          and visceral ganglia jointed by nerves.

•      Sexes are separate but some are hermaphrodites.

•      Fertilization may be internal or external.