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A protist (/ ˈ p r oʊ t ɪ s t / PROH-tist) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus.Protists do not form a natural group, or clade, but are a polyphyletic grouping of several independent clades that evolved from the last eukaryotic common ancestor.
Protists are distributed across all major groups of eukaryotes, including those that contain multicellular algae, green plants, animals, and fungi. If photosynthetic and fungal protists are distinguished from protozoa, they appear as shown in the phylogenetic tree of eukaryotic groups.
Autotrophic protists that make their own food without needing to consume other organisms, usually by photosynthesis (sometimes by chemosynthesis) Green algae, Pyramimonas: Red and brown algae, diatoms, coccolithophores and some dinoflagellates. Plant-like protists are important components of phytoplankton discussed below. Animal-like
Phytoplankton are very diverse, comprising photosynthesizing bacteria (cyanobacteria) and various unicellular protist groups (notably the diatoms). Many other organism groups formally named as phytoplankton, including coccolithophores and dinoflagellates, are now no longer included as they are not only phototrophic but can also eat. [6]
[7] [8] Fungi, bacteria, and protists that feed on living plants are usually termed plant pathogens (plant diseases), while fungi and microbes that feed on dead plants are described as saprotrophs. Flowering plants that obtain nutrition from other living plants are usually termed parasitic plants. There is, however, no single exclusive and ...
All eukaryotes apart from animals, plants and fungi are considered protists. [1] Its field of study therefore overlaps with the more traditional disciplines of phycology , mycology , and protozoology , just as protists embrace mostly unicellular organisms described as algae , some organisms regarded previously as primitive fungi , and protozoa ...
Flowering plants do not produce flagellate cells, but ferns, mosses, green algae, and some gymnosperms and closely related plants do so. [2] Likewise, most fungi do not produce cells with flagellae, but the primitive fungal chytrids do. [3] Many protists take the form of single-celled flagellates. Flagella are generally used for propulsion ...
Protozoans are protists that feed on organic matter such as other microorganisms or organic tissues and debris. [ 31 ] [ 32 ] Historically, the protozoa were regarded as "one-celled animals", because they often possess animal -like behaviours, such as motility and predation , and lack a cell wall , as found in plants and many algae .