classification of invertebrates on basis of major and minor phyla

These phylum were later classified as Major and Minor Phyla on the basis of their number of species and their ecological importance. According to first condition there are only 11 phyla. They are Porifera, coelenterata, Platyhelminthes, Rotifera, Nematoda, Mollusca, Annelida, Arthropoda, Ectoprocta and Echinodermata. These are called Major phyla and remaining 19 are called Minor phyla. Again according to the second condition among these 11 phyla only among 9 are included in new classification. The nine phyla which are included are Porifera, coelenterata, Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda, Echinodermata. The two phyla are removed because they do not play any role in ecological communities.

Brief of Mollusca’s class-GASTROPODA

              The word Gastropoda is derived from two Greek words gaster=belly and podos=foot. It has three subclass namely Prosobranchia ,Opisthobranchia and  Pulmonata.The subclass Prosobranchia has three orders. The three orders are as follow. a) order1:-Archaeogastropoda b)order2:-Mesogastropoda c)order3:-Stenoglossa

         The subclass Opisthobranchia has 11 orders. They are as follow .

a) order1:-Onchidiacea                       b)order2:-Cephalaspidea         

 c) order3:-Anaspidea or Aplysiacea  d) order4:-Pteropoda

e) order5:-Acochillidiacea                   f) order6:-Phililnoglossacea

g) order7:-Saccoglossa                         h) order8:-Notaspidea

i) order9:-Nudibranchia                        j) order10:-Rhodopacea

k)order11:-Pyramidellacea                       

 The subclass Pulmonata has two orders namely as

a) order1:-Bassommatophora   b) order2:-Stylommatophora