Practice question

Porifera represent morphologically simplest multicellular animals at cellular grade organization lacking true tissues defined by basement membranes, no organs, no symmetry, no nervous system, no muscle, no germ layers, no gut exclusively aquatic mostly marine but few freshwater Spongillidae sessile filter feeders. Body wall contains outer pinacoderm inner choanoderm of collar cells choanocytes driving water through aquiferous system of pores canals chambers mesohyl with amoebocytes spicules silica or carbonate and spongin fibers. Reproduction both asexual budding gemmules and sexual with larvae. Totipotent cells minimal division. Thus features such as nerve net muscle gut nephridia absent distinguishing Parazoa from Eumetazoa.