Cell Aggregate Plan

In the cell aggregate plan, the body is not built up into true tissues or organs. Cells are present but show minimal division of labour and cooperate only loosely, so the body behaves more like a colony of different cell types than an integrated organism. This is the body plan seen in Phylum Porifera (sponges), where the body is typically asymmetrical and pierced by numerous minute pores called ostia through which water enters a central cavity, the spongocoel, before leaving through a single larger opening, the osculum. Flagellated cells lining this canal system, th …