Protozoa (sg.: protozoan or protozoon; alternative plural: protozoans) are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris.

Protozoa are microscopic unicellular eukaryotes that have a relatively complex internal structure and carry out complex metabolic activities. Some protozoa have structures for propulsion or other types of movement. On the basis of light and electron microscopic morphology, the protozoa are currently classified into six phyla.

Aug 3, 2023 · With advancements in taxonomy, some of these organisms are reclassified into separate phyla. Examples. In this phylum, obligate intracellular parasites reside, and most of its members are characterized by a specialized organelle called the apical complex.

Apr 28, 2017 · Organisms known as protozoa include a wide range of organisms, most of which are free-living single-celled eukaryotes. Therefore, protozoa fit into the Domain Eukarya.

Protozoa are unicellular, eukaryotic, heterotrophic organisms. They are either free-living or parasites. There are around 65000 species of protozoans categorised in different groups. They lack a cell wall.

Aug 3, 2023 · Protozoa may be defined as “microscopic acellular animalcules existing singly or in colonies, without tissue and organs, having one or more nuclei”. There are about 50,000 known species of Phylum Protozoa. Protozoans exhibit mainly two forms of life; free-living (aquatic, freshwater, seawater) and parasitic (ectoparasites or endoparasites).

Protozoa in GBIF Secretariat (2023). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2025-03-21. Cavalier-Smith, T. (2009). Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree. <em>Biology Letters.</em> 6 (3): 342-345. Margulis, L.; Schwartz, K.V. (1998).

Most accepted classification of protozoa is given by BM Honigberg and others based on the scheme given by the committee on Taxonomy and Taxonomic problems of the society of Protozoologists divides this phyla into 4 subphyla. SUBPHYLUM I: SARCOMASTIGOPHORA (Gr. Sarcodes=fleshy; mastix=whip; phoros=bearing)

Seven phyla of PROTOZOA are accepted in this classification—SARCOMASTIGOPHORA. LABYRINTHOMORPHA, APICOMPLEXA, MICROSPORA, ASCETOSPORA, MYXOSPORA, and CILIOPHORA.

Protozoa are single-celled organisms without cell walls. They are believed to be a part of the microbial world as they are unicellular and microscopic. There is a great deal to know about their classification, characteristics and more. First animals? The term protozoa implies ‘first animals’.