![]() ![]() Some sponges are vase-like or cylindrical, but the majority form massive erect or globular or irregular branching masses.ĥ. Thus, the multicellular body organization in sponges is most primitive, merely of cellular grade.Ĥ. (iv) there is no nervous system to control and co-ordinate the functions of different cells. (iii) similar cells do not form well-defined and permanent tissues and (ii) cell-differentiation is not permanent i.e., cells can easily change from one to another type, (i) the cell varieties are comparatively fewer, Cells in their bodies exhibit a beginning of ‘Division of Labour. Porifera or sponges are the simplest and lowest multicellular animals. All sponges occur as apparently inert outgrowths upon solid objects and hence sedentary.ģ. Only about 150 species inhabit freshwater. About 10,000 species of sponges are known.
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