4. Diversity In Living Organism
Phylum - Porifera
Phylum - Porifera :
Sessile (stalk-less) and marine except one group that lives in fresh water.
Simplest multicellular, diploblastic animals.
Have organisation at cellular colony level. Thus, cells are loosely held together and do not form tissues.
Asymmetrical or radially symmetrical. Sponges may be vase-like, rounded, sac-like branched.
Body is perforated by numerous pores, the ostia that open into a canal system having canals and chambers lined with collared flagellated cells or choanocytes. Examples -
Sycon, Euplectella, (Venus flower basket) Spongilla (Fresh water sponge).