Marine Biology (2+1)

11.Genus: Thalassiosira - Diatom

                                                            

Phylum : Annelida and Mollusca

Class : Polychaeta and Gastropoda

Description: Primitive polychaete worms and molluscs posses trochopore larva. The larva of a polychaete is almost spherical and at its upper pole has a little tuft of long cilia and sensory cells, the so called apical sense organs. The mouth, located equatorially leads into a gut which passes via a little round stomach and a short intestine to open at an anus at the lower pole. A main ciliated girdle (prototroch or preoral band of cilia) runsaround the sphere just above the equator. The cilia help in spinning these spheres like a top. This motion creates ciliary currents that draw minute particles of food from nearby areas into the mouth.