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GENERAL CHARACTERS OF PORIFERA, •, •, •, •, •, •, •, •, •, •, •, •, •, •, , 6., , These are commonly known as sponges., These are multicellular animals without tissue and organ system., These are aquatic animals, most of them are marine and few are fresh water form., These are diploblastic animals .body is made up of two layers namely outer ectoderm and, inner endoderm., The endoskeleton in the form of spicules or sponginfibers or both., These are solitary or sedentary,they remains attached to substratum and live in colony., The body surface is perforated by many pores called Ostia,through which water enters the, body and expelled out through a large aperture called osculum., The body contain large cavity, it is called as spongocoal., The canal system is present, The mesenchyme consist of numerous cells, cells are having different shape and size and, performing different functions., The spongocoal opens outside through a large aperture called osculum, These are bilatary symmetrical or radially symmetrical or asymmetrical., These have great power of regeneration, any small fragment of the body is capable of, growing in to a complete sponge., On the basis of an endoskeleton, whether spicules or spongin fibers present or absent,the, phylum porifera have been divided into three classes namely1) Class - Calcarea (spicules are simple and made up of calcium carbonate), 2) Class - Hexactinellida (spicules are made up of silica,siliceous spicules), 3) Class - Demospongia (endoskeleton is made up of spicules or sponginfibersor both are, present, , PHYLUM - PORIFERA, , CLASS - CALCARIA, Calcarious spicules present., Ex. Sycon., , CLASS - HEXACTINELLIDA, Skeleton made up of, triaxon,hexactinal siliceous, spicules., Ex. Hyalonema, Euplectella., , CLASS - DEMOSPONGIA, Skeleton either siliceous, spicules or spongin fiber of, combination of both., Ex. Spongilla.