Heterotrophs consume organic molecules from other organisms. Chaonocytes are fluid driving cells that line central cavity flagella draw water through pores in ostium cells water goes out of the osculum. Walls can contain amoebocytes (work in digestion and can differentiate into other cells, and secret skeletal spicules) Some have symbiotic relationship with green algae. Filter-feeding heterotrophs (no photosynthetic capability or pigment) Has folded walls containing incurrent canals (open to outside) and flagellated canals (open to inside) Contain sponging fibers (which are flexible unlike spicules) Budding or release of amoebocytes through gemmules. Gemmules can develop into mature adult in favorable conditions. Fertilization forms a zygote and the embryo is expelled from the sponge. Have ectoderm and endoderm separated by mesoglea. Have true tissues but not true organs. Alternation between polyp & medusa is polymorphism. Zygote develops into planula larvae which settles onto the substrate to form a polyp. Polyp produces a ephyrae which develops into mature medusae.