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Protozoa

Pronunciation: pro'to-zo'a

Definition: Formerly considered a phylum, now regarded as a subkingdom of the animal kingdom, including all of the so-called acellular or unicellular forms. They consist of a single functional cell unit or aggregation of nondifferentiated cells, loosely held together and not forming tissues, as distinguishes the Animalia or Metazoa, which include all other animals. Protozoa were formerly divided into four classes: Sarcodina, Mastigophora, Sporozoa, and Ciliata; new classifications employ higher taxa (phyla, subphyla, and superclasses) and a number of major subdivisions.

[proto- + G. zoon, animal]

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© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.

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