Phylum Porifera - Sponges. Among the most ancient animals Mostly marine but some fresh water Porifera - literally means “pore bearer”, which is appropriate because they have tiny openings all over their body Once thought to be plants because they are sessile . What are Sponges?.
Porocytes = pore cells
Choanocyte = collar cell
Spongocoel = central cavity
Mesohyl = jelly-like inner layer