metazoa

Met`a*zo"a, n. pl. Etym: [NL., fr. Gr. (Zoöl.) Defn: Those animals in which the protoplasmic mass, constituting the egg, is converted into a multitude of cells, which are metamorphosed into the tissues of the body. A central cavity is commonly developed, and the cells around it are at first arranged in two layers, -- the ectoderm and endoderm. The group comprises nearly all animals except the Protozoa.

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