Phylum Mollusca

by • 29/01/2012 • New Pattern Biology NotesComments (0)512

8.         Phylum Mollusca:  (Important Characters)

i)          These animals are found in water, (i.e fresh water as well as marine water) while some are found on land (i.e gardened lawn)

ii)         Animals have a soft, fleshy and unsegmented body which is enclosed in a thin fleshy cover called mantle, which produces shell for protection and support.

iii)        Shells are hard and made up of Calcium Carbonate (absent in Octopus).

iv)        They have a muscular foot, for locomotion.

v)         They respire through Gills and Lungs.

vi)        Head is prominent while Mouth, Eyes, and Tentacles are round on the head.

vii)       They are triploblastic animals.

viii)      Radula is present in the mouth of molluscs which is used for scraping, tearing and pulling food.

 

 

Common Examples:        

Snail, Pear Oyster, Squid, Octopus, Fresh water Mussels, Sepia, Cowries etc.

Squids are the largest invertebrates. Pearls are obtained from pearl Oysters.

 

Snails:

Snails are commonly found in garden and lawn. Some are marines. They have spirally coiled shells. Shell has many compartments last compartment is the largest and where snail lives. Head bears two tentacles having two Eyes. Inside the mouth a tongue like structure present which is called Radulla it is for feeding and scraping. A big muscular foot is present which is used for locomotion.

 

 

Fresh Water Mussels:       They are found in water. They have a shell which is made up of two plates joined together by hinge joint. They have a soft body and containing a ventral muscular food for locomotion.

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