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Zoarium, zō-ā′ri-um, n. the colony of the polypides of a polyzoan.

Most, if not all species are hermaphrodite, eggs and spermatozoa being produced either simultaneously or in succession by each individual, or by certain individuals in each zoarium.

The whole zoarium can be released in this way and occasionally drops through the water, and is perhaps carried by currents from one place to another in so doing.

The zoarium as a whole is either recumbent and adherent or at least partly vertical.

In his P. m�lleri the zoarium is always recumbent and the polypide has 8 tentacles, whereas in P. articulata or ehrenbergi the tentacles number 16 and upright branches are usually developed.