Protist - Wikipedia Jump to content Main menu Main menu move to sidebar hide Navigation Main page Contents Current events Random article About Wikipedia Contact us Contribute Help Learn to edit Community portal Recent changes Upload file Special pages Search Search Appearance Donate Create account Log in Personal tools Donate Create account Log in Contents move to sidebar hide (Top) 1 Definition 2 Morphology 3 Classification Toggle Classification subsection 3.1 Brief history 3.2 Modern classification and diversity 3.3 Predicted diversity 4 Biology Toggle Biology subsection 4.1 Nutrition 4.1.1 Phagotrophy 4.1.2 Osmotrophy 4.1.3 Mixotrophy 4.2 Homeostasis 4.3 Mitochondria and respiration 4.4 Cytoskeleton 4.5 Sensory perception 4.6 Symbionts 5 Life cycle and reproduction Toggle Life cycle and reproduction subsection 5.1 Asexual reproduction 5.2 Sexual reproduction 5.2.1 Factors inducing sexual cycles 5.3 Cycles in pathogenic protists 6 Habitats Toggle Habitats subsection 6.1 Extreme habitats 6.2 Biomass comparison 7 Ecological roles Toggle Ecological roles subsection 7.1 Primary producers 7.2 Consumers 7.3 Decomposers 7.4 Parasites and pathogens 7.5 Mutualists and commensals 7.6 Biogeochemical cycles 8 Evolution and fossil record Toggle Evolution and fossil record subsection 8.1 First fossils and stem eukaryotes 8.2 Radiation of crown eukaryotes 8.3 Neoproterozoic expansion 8.4 Phanerozoic diversifications and major events 9 See also 10 Footnotes 11 References 12 External links Toggle the table of contents Protist 121 languages Afrikaans Alemannisch አማርኛ Aragonés अंगिका العربية مصرى অসমীয়া Asturianu Azərbaycanca تۆرکجه Башҡортса Boarisch Žemaitėška Беларуская (тарашкевіца) Беларуская Български বাংলা Bosanski Català کوردی Čeština Cymraeg Dansk Deutsch Ελληνικά Esperanto Español Eesti Euskara Estremeñu فارسی Suomi Võro Français Nordfriisk Gaeilge Galego Gaelg עברית हिन्दी Fiji Hindi Hrvatski Kreyòl ayisyen Magyar Interlingua Bahasa Indonesia Interlingue Ilokano Ido Íslenska Italiano 日本語 Patois Jawa ქართული Қазақша ಕನ್ನಡ Yerwa Kanuri 한국어 Kurdî Kernowek Latina Lëtzebuergesch Lingua Franca Nova Ligure Lietuvių Latviešu Madhurâ Malagasy Македонски മലയാളം Монгол Bahasa Melayu မြန်မာဘာသာ Napulitano Plattdüütsch Nederlands Norsk nynorsk Norsk bokmål Occitan Oromoo ਪੰਜਾਬੀ Polski Piemontèis پنجابی Português Runa Simi Română Русский Саха тыла Sardu سنڌي Srpskohrvatski / српскохрватски සිංහල Simple English Slovenčina Slovenščina Soomaaliga Српски / srpski Sunda Svenska Kiswahili தமிழ் తెలుగు Тоҷикӣ ไทย Tagalog Lea faka-Tonga Türkçe Татарча / tatarça Українська اردو Vepsän kel’ Tiếng Việt Winaray 吴语 ייִדיש 閩南語 / Bân-lâm-gí 粵語 中文 Edit links Article Talk English Read Edit View history Tools Tools move to sidebar hide Actions Read Edit View history General What links here Related changes Upload file Permanent link Page information Cite this page Get shortened URL Switch to legacy parser Print/export Download as PDF Printable version In other projects Wikimedia Commons Wikispecies Wikidata item Appearance move to sidebar hide From Wikipedia, the free encyclopedia (Redirected from Protists) Eukaryotes other than animals, plants or fungi For the journal, see Protist (journal). Not to be confused with Protest. {{cite journal|first1=Jürgen F. H.|last1=Strassert|first2=Iker|last2=Irisarri|first3=Tom A.|last3=Williams|first4=Fabien|last4=Burki|title=A molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids|journal=Nature Communications|date=25 March 2021|volume=12|issue=1|page=1879|doi=10.1038/s41467-021-22044-z|doi-access=free|pmid=33767194|pmc=7994803|bibcode=2021NatCo..12.1879S }}</ref>|earliest=2386}}"},"image":{"wt":"Protist collage 2.jpg"},"image_alt":{"wt":""},"image_caption":{"wt":"Examples of protists. Clockwise from top left: [[red algae]], [[kelp]], [[ciliate]], [[golden algae]], [[dinoflagellate]], [[metamonad]], [[amoeba]], [[slime mold]]."},"auto":{"wt":"yes"},"parent":{"wt":"Eukaryota"},"subdivision_ranks":{"wt":"Major subdivisions <!--MUST be short, CAM and TSAR should be excluded as they are not universally supported or frequently claimed as important clades, unlike say SAR or Diaphoretickes.-->"},"subdivision":{"wt":"* [[Amorphea]]\n** [[Amoebozoa]]\n** [[Obazoa]] <small>(including [[animal]]s and [[fungi]])</small>\n* [[Ancyromonadida]]\n* [[Heliomonadida]]\n* [[CRuMs]]\n* [[Discoba]]\n* [[Malawimonadida]]\n* [[Metamonada]]\n* [[Diaphoretickes]]\n** [[Archaeplastida]] <small>(including [[Embryophyte|land plants]])</small>\n** [[Pancryptista]]\n**[[Disparia]]\n** [[Haptista]]\n** [[Telonemia]]\n**[[SAR supergroup|SAR]]<!-- The consensus is to display Sar in the taxonomy template only, not in the subdivisions -->\n*** [[Stramenopiles]]\n*** [[Alveolata]]\n*** [[Rhizaria]]"},"excludes":{"wt":"* [[Animal|Animalia]]\n* [[Fungus|Fungi]]\n* [[Embryophyte|Embryophyta]] (land plants)"},"excludes_text":{"wt":"Eukaryotes that are not considered protists"}},"i":2}}]}'> ProtistsTemporal range: Paleoproterozoic–present[1] Pha. Proterozoic Archean Had. red algae</a>, <a rel=\"mw:WikiLink\" href=\"./Kelp\" title=\"Kelp\" id=\"mwDg\">kelp</a>, <a rel=\"mw:WikiLink\" href=\"./Ciliate\" title=\"Ciliate\" id=\"mwDw\">ciliate</a>, <a rel=\"mw:WikiLink\" href=\"./Golden_algae\" title=\"Golden algae\" id=\"mwEA\">golden algae</a>, <a rel=\"mw:WikiLink\" href=\"./Dinoflagellate\" title=\"Dinoflagellate\" id=\"mwEQ\">dinoflagellate</a>, <a rel=\"mw:WikiLink\" href=\"./Metamonad\" title=\"Metamonad\" id=\"mwEg\">metamonad</a>, <a rel=\"mw:WikiLink\" href=\"./Amoeba\" title=\"Amoeba\" id=\"mwEw\">amoeba</a>, <a rel=\"mw:WikiLink\" href=\"./Slime_mold\" title=\"Slime mold\" id=\"mwFA\">slime mold</a>.","txt":"Examples of protists. Clockwise from top left: red algae, kelp, ciliate, golden algae, dinoflagellate, metamonad, amoeba, slime mold."}]]}'> Examples of protists. Clockwise from top left: red algae, kelp, ciliate, golden algae, dinoflagellate, metamonad, amoeba, slime mold. Scientific classification Domain: Eukaryota Major subdivisions Amorphea Amoebozoa Obazoa (including animals and fungi) Ancyromonadida Heliomonadida CRuMs Discoba Malawimonadida Metamonada Diaphoretickes Archaeplastida (including land plants) Pancryptista Disparia Haptista Telonemia SAR Stramenopiles Alveolata Rhizaria Eukaryotes that are not considered protists Animalia Fungi Embryophyta (land plants) A protist (/ˈproʊtɪst/ 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 paraphyletic group encompassing the entire eukaryote tree of life, from which land plants, animals, and fungi evolved. They are primarily single-celled, exhibiting a wide range of forms such as amoebae, ciliates, thick-walled microalgae and, more commonly, flagellates. Several transitions to multicellularity have occurred among protists, from colonies with alternating cell types to giant slime molds, fungus-like organisms, and seaweeds with differentiated tissues. Protists were historically regarded as a separate taxonomic kingdom known as Protista or Protoctista, or were lumped together as part of the traditional plant and animal kingdoms as algae and protozoa, respectively. With the advent of molecular phylogenetics and electron microscopy studies, some protists were shown to be more closely related to animals or plants than to other protists, and algae were found to be intermixed with protozoa. The classification suffered major revisions, as seemingly unrelated forms were found to be evolutionarily related, and vice versa. In modern classifications, protists are spread across several large clades known as supergroups, many of them containing disparate forms. For example, the Archaeplastida includes mostly phototrophs like red and green algae, from which land plants evolved. Opisthokonta groups fungi, animals, and their single-celled relatives. Amoebozoa and Rhizaria harbor the majority of amoeboid organisms, such as testate amoebae, foraminifers and radiolarians. Stramenopiles and Alveolata are diverse groups of flagellates, many of which have evolved into major parasites (e.g., oomycetes, apicomplexans) or phototrophs (diatoms, brown algae, dinoflagellates). The earliest diverging groups, collectively known as Excavata (e.g., euglenids, metamonads), are flagellates that represent the ancestral traits of the last eukaryotic common ancestor (LECA). Despite the comparatively low number of described species, protists compose the majority of eukaryotic diversity as indicated by environmental DNA studies. Most protists are yet undescribed. Protists encompass almost all of the biological traits seen in eukaryotes, and many exhibit unique adaptations. These include a range of nutritional modes through specialized feeding structures (phagotrophy, osmotrophy, myzocytosis) or chloroplasts (phototrophy), often mixing both as mixotrophy. Cellular respiration also varies due to modifications of their mitochondria. Almost all protists have a complex cytoskeleton composed of relatively conserved structures across evolution, namely a flagellar apparatus with basal bodies from which microtubules emerge and support the remaining cellular structures. Many protists have unique organelles that serve other functions, such as contractile vacuoles for homeostasis, or eyespots for light perception. Protist cells tend to host symbionts such as bacteria and archaea, usually to support their metabolism and nutrition. Although traditionally presumed to be asexual, protists are capable of sexual reproduction, and can exhibit diverse and complex life cycles with different generations and life stages. Protists are abundantly present in all ecosystems, including extreme habitats, as important components of the biogeochemical cycles and trophic webs. As producers, they are responsible for a large portion of global primary production and carbon fixation. As consumers and decomposers, they regulate fungal and bacterial populations, and release nutrients to other trophic levels. Some form mutualistic relationships with other protists or animals such as corals and termites. Others are important parasites. Pathogenic protists cause many well-known human and animal diseases such as malaria and toxoplasmosis, or significant plant diseases like clubroot and potato blight. Free-living protists can also negatively impact aquatic life as harmful algal blooms. The early evolution of protists corresponds with the evolution of eukaryotes, which split from archaea around 3 billion years ago and eventually gave rise to a common ancestor (LECA) with essential traits such as mitochondria and a complex endomembrane system, some time during the Paleo- or Mesoproterozoic eras. In the gap between these two events, fossils are often interpreted as stem-group eukaryotes, with intermediate traits. Following the appearance of LECA, its descendants (crown-group eukaryotes) experienced a rapid diversification in the span of 300 million years that originated the modern supergroups. Still, their abundance in the fossil record remained low until the Neoproterozoic, when the first fossils of opisthokonts, amoebae, and multicellular algae appear. Throughout the Phanerozoic, protists evolved into the forms that dominate ecosystems today, leaving an extensive fossil record of primarily siliceous and calcareous shells. Definition [edit] The tree of life showing the position of protists, from which all other eukaryotes evolved. Protists are defined as …