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多孔动物门（學名：Porifera）为原始的多细胞生物，也称海绵动物门（Spongiatia或Spongia），一般称为海绵。海绵没有神经、消化和循环系统，相反，它們大多依靠海水流過自己的身體来獲得食物和氧氣並消除廢物，就像海底中的濾水器。
由於形状像植物，而且根植在海底中，所以海綿千百年來都被認為是植物，但後來發現它們幾乎具備所有最基本的動物特徵，所以到十九世纪中期才被歸入動物界裡頭。但近期基於基因組資訊與系統發生學的更多證據，所以應否把它們保留在動物界還是獨立出來自成一個界別的論點在生物學界仍在不斷討論中。
Sponges are animals of the phylum Porifera (meaning "pore bearer"). 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. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes.