What meaning of phylum porifera?

Porifera (pōrĭf'ərə) [Lat.,=pore bearer], animal phylum consisting of the organisms commonly called http://www.answers.com/topic/sponge. 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.