] [Lat., = pore bearer], animal phylum consisting of the organisms commonly called sponges
. It is the only phylum of the animal subkingdom Parazoa and represents the least evolutionarily advanced group of the animal kingdom. All adult sponges are sessile (nonmotile), and nearly all are marine; there are four families of freshwater sponges. Sponges are subdivided into three classes.
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