Protozoa are single celled organisms. Protozoa (meaning "first animals") are heterotrophic, single-celled or colonial eukaryotes. 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. Furthermore, the scientist has described more than 50 thousand species of Protozoa. 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. Protozoa Classification and Examples. Protozoa is a phylum having unicellular heterotrophs. They are believed to be a part of the microbial world as they are unicellular and microscopic. Protozoa is a single cell animal that we can find in every possible habitat on earth. 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. See more. Protozoa are divided into four major groups based on the structure and the part involved in the locomotion: 1. It comes under Kingdom Protista. Protozoa definition, a major grouping or superphylum of the kingdom Protista, comprising the protozoans. Protozoa are non-phototrophic, unicellular, eukaryotic microorganisms with no … home >> biology >> definition They belong among the eukaryotes , and are often grouped in the kingdom Protista together with the plant-like algae . Protozoa. Before then, the microscopic protozoa, defined by their organelles, were unable to be fully appreciated. The group of organisms known as 'protozoa' are defined by a few of their shared characteristics. Moreover, they are herbivores, carnivores, and omnivores. There is a great deal to know about their classification, characteristics and more. Protozoa are single-celled organisms without cell walls. Definition: Unicellular or acellular, eukaryotic and com­monly motile heterotrophic organisms are called Protozoa. It was first coined in the 1800s. 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. Learn more about it. The word protozoa comes from the word protos, which was Greek for "first," and zoia which meant "animal." They have flagella for locomotion All protozoans are eukaryotes and therefore possess a “true,” or membrane-bound, nucleus. They live in a wide variety of moist habitats including fresh water, marine environments and the soil. Mastigophora or Flagellates: They are parasites or free-living. 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