多孔动物门（学名：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，它们大多依靠海水流过自己的身体来获得食物和氧气并消除废物，就像海底中的滤水器。

由于形状像植物，而且根植在海底中，所以海绵千百年来都被认为是植物，但后来发现它们几乎具备所有最基本的动物特征，所以到十九世纪中期才被归入动物界里头。但近期基于基因组信息与系统发生学的更多证据，所以应否把它们保留在动物界还是独立出来自成一个界别的论点在生物学界仍在不断讨论中。

Sponges are animals of the phylum Porifera (/pɒˈrɪfərə/; 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.