Sponges, the members of the phylum Porifera; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Most sponges rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes.