ˌprōd.əˈzōə, -ōtə- noun plural
Usage: capitalized
Etymology: New Latin, from prot- + -zoa
: a phylum or subkingdom of animals that have an essentially acellular structure though varying from simple uninucleate protoplasts (as most amoebas) to cell colonies (as volvox), syncytia (as pelomyxa), or highly organized protoplasts (as various higher ciliates) far more complex in organization and differentiation than most metazoan cells, that consist of a protoplasmic body either naked or enclosed in a test, fixed to the substrate or free, and immobile, creeping by means of pseudopodia or protoplasmic flow, or freely motile by cilia or flagella, that are similarly varied in physiological characteristics with nutrition holophytic, saprophytic, or holozoic, with reproduction asexual involving nuclear division usually by more or less modified mitosis associated with cytoplasmic binary fission or with multiple fission or exogenous or endogenous budding or sexual by means of conjugation, of isogamous or anisogamous hologamy or of processes approaching the fertilization processes of metazoans, and with a life cycle simple (as in an amoeba) or extremely complex (as in many sporozoans), that are represented by one form or another in almost every kind of habitat (as fresh or salt water, soil, sewage, the latex of plants, and the bodies of living animals), and that include parasitic forms which are among the gravest plaguers of man and his domestic animals — compare malaria parasite , trypanosome ; ciliophora , plasmodroma ; eimeria , metazoa , parazoa , protista