Protozoa Classification and Examples. They have flagella for locomotion The group of organisms known as 'protozoa' are defined by a few of their shared characteristics. Protozoa are single celled organisms. Mastigophora or Flagellates: They are parasites or free-living. Learn more about it. Protozoa definition, a major grouping or superphylum of the kingdom Protista, comprising the protozoans. Protozoa. home >> biology >> definition They belong among the eukaryotes , and are often grouped in the kingdom Protista together with the plant-like algae . Before then, the microscopic protozoa, defined by their organelles, were unable to be fully appreciated. All protozoans are eukaryotes and therefore possess a “true,” or membrane-bound, nucleus. It is a loose assemblage of different groups of unicellular organisms and they do not belong to a monophyletic Unease, probably shares a member of polyphyletic lineases. It comes under Kingdom Protista. They are believed to be a part of the microbial world as they are unicellular and microscopic. Protozoa [pro″to-zo´ah] a subkingdom (formerly a phylum) comprising the unicellular eukaryotic organisms; most are free-living, but some lead commensalistic, mutualistic, or parasitic existences. Protozoa is a single cell animal that we can find in every possible habitat on earth. Protozoa (meaning "first animals") are heterotrophic, single-celled or colonial eukaryotes. Protozoa is a phylum having unicellular heterotrophs. Protozoa. They come in many different shapes and sizes ranging from an Amoeba which can change its shape to Paramecium with its fixed shape and complex structure. Protozoa are non-phototrophic, unicellular, eukaryotic microorganisms with no … Protozoa are single-celled organisms without cell walls. Protozoan, organism, usually single-celled and heterotrophic (using organic carbon as a source of energy), belonging to any of the major lineages of protists and, like most protists, typically microscopic. Protozoa are divided into four major groups based on the structure and the part involved in the locomotion: 1. There is a great deal to know about their classification, characteristics and more. It was first coined in the 1800s. Definition: Unicellular or acellular, eukaryotic and com­monly motile heterotrophic organisms are called Protozoa. Moreover, they are herbivores, carnivores, and omnivores. See more. Furthermore, the scientist has described more than 50 thousand species of Protozoa. The word protozoa comes from the word protos, which was Greek for "first," and zoia which meant "animal." They live in a wide variety of moist habitats including fresh water, marine environments and the soil. 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