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. [1][2] Historically, protozoans were regarded as …

Feb 28, 2025 · 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. All protozoans are eukaryotes and therefore possess a …

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 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 · Protozoa are unicellular eukaryotic microorganisms having a membrane-bound nucleus and other organelles within their cells. Despite their small size, they are incredibly diverse and exist in various aquatic and terrestrial environments worldwide. More than 50,000 species are known, most of which are free-living organisms.

Oct 14, 2022 · Protozoa are a group of 65,000 (or possibly more) single-cell organisms. They are part of what's called the eukarya domain and include the cells that make up humans, animals, plants, fungi, and parasites. Most humans will "host" a …

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).

Oct 1, 2024 · Protozoa are a diverse group of single-celled eukaryotic organisms that can be either free-living or parasitic. They primarily feed on organic matter, including microorganisms and organic debris. Protozoa are characterized by their lack of a rigid cell wall, motility, and heterotrophic feeding habits.

Apr 9, 2025 · Protozoa, or protozoans, are single-celled, eukaryotic microorganisms. Some protozoa are oval or spherical, others elongated. Still others have different shapes at different stages of the life cycle. Cells can be as small as 1 μm in diameter and as large as 2,000 μm, or 2 mm (visible without magnification).