View source for Biology:Amoeba

{{Short description|Polyphyletic group of unicellular eukaryotes with the ability to shapeshift}}
[[File:Amoeba collage.jpg|right|thumb|upright=1.5|Clockwise from top right: ''Amoeba proteus'', ''Actinophrys sol'', ''Acanthamoeba'' sp., ''Nuclearia thermophila''., ''Euglypha acanthophora'', neutrophil ingesting bacteria.]]

An '''amoeba''' ({{IPAc-en|ə|ˈ|m|iː|b|ə}}; less commonly spelled '''ameba''' or '''amœba'''; {{plural form}}: '''am(o)ebas''' or '''am(o)ebae''' {{IPAc-en|ə|ˈ|m|iː|b|i}}),<ref>[http://www.oxforddictionaries.com/definition/english/amoeba "Amoeba"] {{Webarchive|url=https://web.archive.org/web/20151122195608/http://www.oxforddictionaries.com/definition/english/amoeba |date=22 November 2015 }} at Oxforddictionaries.com</ref> often called an '''amoeboid''', is a type of [[Biology:Cell|cell]] or [[Biology:Unicellular organism|unicellular organism]] with the ability to alter its shape, primarily by extending and retracting [[Biology:Pseudopodia|pseudopods]].<ref>{{Cite book|title=Dictionary of Microbiology and Molecular Biology, 3rd Edition, revised|url=https://archive.org/details/dictionarymicrob00sing_558|url-access=limited|last=Singleton|first=Paul|publisher=John Wiley & Sons|year=2006|isbn=978-0-470-03545-0 |location=Chichester, UK|pages=[https://archive.org/details/dictionarymicrob00sing_558/page/n42 32]}}</ref> Amoebae do not form a single [[Biology:Taxonomy|taxonomic group]]; instead, they are found in every major [[Biology:Lineage (evolution)|lineage]] of [[Biology:Eukaryote|eukaryotic]] organisms. Amoeboid cells occur not only among the [[Biology:Protozoa|protozoa]], but also in [[Biology:Fungi|fungi]], [[Biology:Algae|algae]], and animals.<ref name=":1">{{cite web|url=http://tolweb.org/notes/?note_id=51|title=Amoebae: Protists Which Move and Feed Using Pseudopodia|author=David J. Patterson|publisher=Tree of Life web project|access-date=21 September 2009|archive-url=https://web.archive.org/web/20100615015212/http://tolweb.org/notes/?note_id=51|archive-date=15 June 2010|url-status=live}}</ref><ref>{{cite web|url=http://www.bms.ed.ac.uk/research/others/smaciver/amoebae.htm |title=The Amoebae |publisher=The University of Edinburgh |url-status=dead |archive-url=https://web.archive.org/web/20090610035748/http://www.bms.ed.ac.uk/research/others/smaciver/amoebae.htm |archive-date=10 June 2009 }}</ref><ref>{{cite web|url=http://www.microscopy-uk.org.uk/mag/wimsmall/sundr.html|title=Sun animalcules and amoebas|author=Wim van Egmond|publisher=Microscopy-UK|access-date=23 October 2005|archive-url=https://web.archive.org/web/20051104122947/http://microscopy-uk.org.uk/mag/wimsmall/sundr.html|archive-date=4 November 2005|url-status=live}}</ref><ref>{{Cite journal|last1=Flor-Parra |first1=Ignacio |last2=Bernal |first2=Manuel |last3=Zhurinsky |first3=Jacob |last4=Daga |first4=Rafael R.|date=2013-12-17|title=Cell migration and division in amoeboid-like fission yeast |journal=Biology Open |volume=3 |issue=1 |pages=108–115|doi=10.1242/bio.20136783 |issn=2046-6390|pmc=3892166 |pmid=24357230}}</ref><ref>{{Cite journal |last1=Friedl |first1=P. |last2=Borgmann|first2=S.|last3=Bröcker|first3=E. B.|date=2001-10-01|title=Amoeboid leukocyte crawling through extracellular matrix: lessons from the Dictyostelium paradigm of cell movement|journal=Journal of Leukocyte Biology |volume=70|issue=4 |pages=491–509 |doi=10.1189/jlb.70.4.491 |issn=0741-5400|pmid=11590185|s2cid=28731650 }}</ref>

[[Microbiologist]]s often use the terms "amoeboid" and "amoeba" interchangeably for any organism that exhibits [[Biology:Amoeboid movement|amoeboid movement]].<ref name=":0">{{cite journal |last1=Marée |first1=Athanasius FM |last2=Hogeweg |first2=Paulien |year=2001 |title=How amoeboids self-organize into a fruiting body: multicellular coordination in Dictyostelium discoideum |journal=Proceedings of the National Academy of Sciences |volume=98 |issue=7|pages=3879–3883 |doi=10.1073/pnas.061535198 |pmid=11274408 |pmc=31146 |doi-access=free }}</ref><ref>{{cite journal |last1=Mackerras |first1=M. J. |last2=Ercole |first2=Q. N. |year=1947 |title=Observations on the action of paludrine on malarial parasites |journal=Transactions of the Royal Society of Tropical Medicine and Hygiene |volume=41 |issue=3|pages=365–376 |doi=10.1016/s0035-9203(47)90133-8 |pmid=18898714 }}</ref>

In older classification systems, most amoebae were placed in the [[Biology:Class|class]] or [[Biology:Subphylum|subphylum]] Sarcodina, a grouping of [[Biology:Unicellular organism|single-celled organisms]] that possess pseudopods or move by [[Biology:Protoplasm|protoplasm]]ic flow. However, molecular phylogenetic studies have shown that Sarcodina is not a [[Biology:Monophyletic|monophyletic]] group whose members share [[Biology:Common descent|common descent]]. Consequently, amoeboid organisms are no longer classified together in one group.<ref name="Pawlowski">Jan Pawlowski: ''The twilight of Sarcodina: a molecular perspective on the polyphyletic origin of amoeboid protists''. Protistology, Band 5, 2008, S. 281–302. [http://protistology.ifmo.ru/num5_4/pawlowski.pdf (pdf, 570 kB)] {{Webarchive|url=https://web.archive.org/web/20130614123442/http://protistology.ifmo.ru/num5_4/pawlowski.pdf |date=14 June 2013 }}</ref>

The best known amoeboid protists are ''Chaos carolinense'' and ''[[Biology:Amoeba proteus|Amoeba proteus]]'', both of which have been widely cultivated and studied in classrooms and laboratories.<ref>{{Cite journal|last=Tan|display-authors=et al|date=2005|title=A simple mass culture of the amoeba Chaos carolinense: revisit|url=http://protistology.ifmo.ru/num4_2/tan.pdf|journal=Protistology|volume=4|pages=185–90|access-date=28 September 2017|archive-url=https://web.archive.org/web/20170929000449/http://protistology.ifmo.ru/num4_2/tan.pdf|archive-date=29 September 2017|url-status=live}}</ref><ref>{{Cite news|url=https://davidwangblog.wordpress.com/relationship-with-humans/|title=Relationship with Humans|date=2013-04-12|work=Amoeba proteus|access-date=2017-09-28|language=en-US|archive-url=https://web.archive.org/web/20170929000804/https://davidwangblog.wordpress.com/relationship-with-humans/|archive-date=29 September 2017|url-status=live}}</ref> Other well known species include the so-called "brain-eating amoeba" ''[[Biology:Naegleria fowleri|Naegleria fowleri]]'', the intestinal parasite ''[[Biology:Entamoeba histolytica|Entamoeba histolytica]]'', which causes amoebic dysentery, and the multicellular "social amoeba" or slime mould ''[[Biology:Dictyostelium discoideum|Dictyostelium discoideum]]''.

==Shape, movement and nutrition==
[[File:PseudopodiaFormsDavidPatterson.jpg|thumb|380px|right|The forms of [[Biology:Pseudopodia|pseudopodia]], from left: polypodial and lobose; monopodial and lobose; filose; conical; reticulose; tapering actinopods; non-tapering actinopods]]
Amoeba do not have cell walls, which allows for free movement. Amoeba move and feed by using pseudopods, which are bulges of [[Biology:Cytoplasm|cytoplasm]] formed by the coordinated action of [[Biology:Actin|actin]] microfilaments pushing out the [[Biology:Plasma membrane|plasma membrane]] that surrounds the cell.<ref>{{Cite book|title=Molecular Biology of the Cell 5th Edition|last=Alberts Eds.|publisher=Garland Science|year=2007|isbn=9780815341055|location=New York|pages=1037|display-authors=0}}</ref> The appearance and internal structure of pseudopods are used to distinguish groups of amoebae from one another. Amoebozoan species, such as those in the genus ''[[Biology:Amoeba (genus)|Amoeba]]'', typically have bulbous (lobose) pseudopods, rounded at the ends and roughly tubular in cross-section. Cercozoan amoeboids, such as ''[[Biology:Euglypha|Euglypha]]'' and ''[[Biology:Gromia|Gromia]]'', have slender, thread-like (filose) pseudopods. [[Biology:Foraminifera|Foraminifera]] emit fine, branching pseudopods that merge with one another to form net-like (reticulose) structures. Some groups, such as the [[Biology:Radiolaria|Radiolaria]] and Heliozoa, have stiff, needle-like, radiating [[Biology:Pseudopodia#Morphology|axopodia]] (actinopoda) supported from within by bundles of microtubules.<ref name=":1"/><ref>{{Cite book|title=Kingdoms and Domains|url=https://archive.org/details/fivekingdomsillu00marg_711|url-access=limited|last=Margulis|first=Lynn|publisher=Academic Press|year=2009|isbn=978-0-12-373621-5|pages=[https://archive.org/details/fivekingdomsillu00marg_711/page/n261 206]–7}}</ref>

{{Multiple image
|total_width=380
|image1=Строение амебы Mayorella sp.jpg
|alt1=Naked amoeba in the genus Mayorella
|image2=Difflugia acuminata.jpg
|alt2=Shell of the testate amoeba Cylindrifflugia acuminata
|footer="Naked" amoeba of the genus ''[[Biology:Mayorella|Mayorella]]'' (left) and shell of the testate amoeba ''Cylindrifflugia acuminata'' (right)
}}

Free-living amoebae may be "[[Biology:Testate amoebae|testate]]" (enclosed within a hard shell), or "naked" (also known as gymnamoebae, lacking any hard covering). The shells of testate amoebae may be composed of various substances, including [[Chemistry:Calcium|calcium]], [[Chemistry:Silica|silica]], [[Chemistry:Chitin|chitin]], or agglutinations of found materials like small grains of sand and the frustules of diatoms.<ref>{{Cite book|title=An Atlas of Freshwater Testate Amoeba|last=Ogden|first=C. G.|publisher=Oxford University Press, for British Museum (Natural History)|year=1980|isbn=978-0198585022|location=Oxford, London, and Glasgow|pages=1–5}}</ref>

To regulate [[Biology:Osmotic pressure|osmotic pressure]], most freshwater amoebae have a contractile [[Biology:Vacuole|vacuole]] which expels excess water from the cell.<ref>{{Cite book|title=Molecular Biology of the Cell 5th Edition|last=Alberts Eds.|publisher=Garland Science|year=2007|isbn=9780815341055|location=New York|pages=663|display-authors=0}}</ref> This [[Biology:Organelle|organelle]] is necessary because freshwater has a lower concentration of solutes (such as salt) than the amoeba's own internal fluids ([[Biology:Cytosol|cytosol]]). Because the surrounding water is [[Biology:Tonicity|hypotonic]] with respect to the contents of the cell, water is transferred across the amoeba's cell membrane by [[Physics:Osmosis|osmosis]]. Without a contractile vacuole, the cell would fill with excess water and, eventually, burst. Marine amoebae do not usually possess a contractile vacuole because the concentration of solutes within the cell are in balance with the [[Biology:Tonicity|tonicity]] of the surrounding water.<ref>Kudo, Richard Roksabro. "Protozoology." Protozoology 4th Edit (1954). p. 83</ref>

==Diet==
[[File:Phagocytosis -- amoeba.jpg|thumb|300px|Amoeba phagocytosis of a bacterium]]
The food sources of amoebae vary. Some amoebae are predatory and live by consuming bacteria and other [[Biology:Protist|protist]]s. Some are [[Biology:Detritivore|detritivore]]s and eat dead organic material.

Amoebae typically ingest their food by [[Biology:Phagocytosis|phagocytosis]], extending pseudopods to encircle and engulf live prey or particles of scavenged material. Amoeboid cells do not have a mouth or [[Biology:Cytostome|cytostome]], and there is no fixed place on the cell at which phagocytosis normally occurs.<ref>Thorp, James H. (2001). Ecology and Classification of North American Freshwater Invertebrates. San Diego: Academic. p. 71. {{ISBN|0-12-690647-5}}.</ref>

Some amoebae also feed by [[Biology:Pinocytosis|pinocytosis]], imbibing dissolved nutrients through [[Biology:Vesicle (biology and chemistry)|vesicles]] formed within the cell membrane.<ref>{{Cite book|title=Biology of Amoeba|url=https://archive.org/details/biologyofamoeba0000jeon|url-access=registration|last=Jeon|first=Kwang W.|publisher=Academic Press|year=1973|location=New York|pages=[https://archive.org/details/biologyofamoeba0000jeon/page/100 100]|isbn=9780123848505}}</ref>

==Size range==
[[File: Ammonia tepida.jpg|thumb|Foraminifera have reticulose (net-like) pseudopods, and many species are visible with the naked eye]]

The size of amoeboid cells and species is extremely variable. The marine amoeboid ''[[Biology:Massisteria|Massisteria voersi]]'' is just 2.3 to 3 [[Micrometre|micrometre]]s in diameter,<ref name="Mylnikov">{{Cite journal|last1=Mylnikov|first1=Alexander P.|last2=Weber|first2=Felix|last3=Jürgens|first3=Klaus|last4=Wylezich|first4=Claudia|date=2015-08-01|title=Massisteria marina has a sister: Massisteria voersi sp. nov., a rare species isolated from coastal waters of the Baltic Sea|journal=European Journal of Protistology|volume=51|issue=4|pages=299–310|doi=10.1016/j.ejop.2015.05.002|issn=1618-0429|pmid=26163290}}</ref> within the size range of many bacteria.<ref>{{Cite web|url=http://classes.midlandstech.edu/carterp/courses/bio225/chap04/lecture2.htm|title=The Size, Shape, And Arrangement of Bacterial Cells|website=classes.midlandstech.edu|access-date=2016-08-21|archive-url=https://web.archive.org/web/20160809135552/http://classes.midlandstech.edu/carterp/courses/bio225/chap04/lecture2.htm|archive-date=9 August 2016|url-status=dead}}</ref> At the other extreme, the shells of deep-sea [[Biology:Xenophyophore|xenophyophore]]s can attain 20&nbsp;cm in diameter.{{r|gooday2011}} Most of the free-living freshwater amoebae commonly found in pond water, ditches, and lakes are [[Physics:Microscopic scale|microscopic]], but some species, such as the so-called "giant amoebae" [[Biology:Pelomyxa|''Pelomyxa palustris'']] and [[Biology:Chaos (genus)|''Chaos carolinense'']], can be large enough to see with the naked eye.

{|class="wikitable"
|-
! Species or cell type
! Size in micrometers
|-
|''[[Biology:Massisteria|Massisteria voersi]]''<ref name=Mylnikov/>
|2.3–3
|-
|''[[Biology:Naegleria fowleri|Naegleria fowleri]]''<ref>{{Cite web|url=http://www.webmd.com/brain/brain-eating-amoeba#1|title=Brain-Eating Amoeba (Naegleria Fowleri): Causes and Symptoms|language=en-US|access-date=2016-08-21|archive-url=https://web.archive.org/web/20160821233242/http://www.webmd.com/brain/brain-eating-amoeba#1|archive-date=21 August 2016|url-status=live}}</ref>
|8–15
|-
|[[Biology:Neutrophil|Neutrophil]] (white blood cell)<ref>{{Cite web|url=http://www.anatomyatlases.org/MicroscopicAnatomy/Section04/Section04.shtml|title=Anatomy Atlases: Atlas of Microscopic Anatomy: Section 4: Blood|website=www.anatomyatlases.org|access-date=2016-08-21|archive-url=https://web.archive.org/web/20160819003652/http://www.anatomyatlases.org/MicroscopicAnatomy/Section04/Section04.shtml|archive-date=19 August 2016|url-status=live}}</ref>
|12–15
|-
|''[[Biology:Acanthamoeba|Acanthamoeba]]''<ref>{{Cite web|url=http://www.arcella.nl/acanthamoeba|title=''Acanthamoeba'' {{!}} Microworld|website=www.arcella.nl|access-date=2016-08-21|archive-url=https://web.archive.org/web/20160818072935/http://arcella.nl/acanthamoeba|archive-date=18 August 2016|url-status=dead}}</ref>
|12–40
|-
|''[[Biology:Entamoeba histolytica|Entamoeba histolytica]]''<ref>{{Cite web|url=https://msu.edu/course/zol/316/ehisscope.htm|title=Microscopy of ''Entamoeba histolytica''|website=msu.edu|access-date=2016-08-21|archive-url=https://web.archive.org/web/20161005024303/https://msu.edu/course/zol/316/ehisscope.htm|archive-date=5 October 2016|url-status=live}}</ref>
|15–60
|-
|''[[Biology:Arcella|Arcella vulgaris]]''<ref>{{Cite web|url=http://www.arcella.nl/arcella-vulgaris|title=''Arcella vulgaris'' {{!}} Microworld|website=www.arcella.nl|access-date=2016-08-21|archive-url=https://web.archive.org/web/20160818211646/http://arcella.nl/arcella-vulgaris|archive-date=18 August 2016|url-status=live}}</ref>
|30–152
|-
|''[[Biology:Amoeba proteus|Amoeba proteus]]''<ref>{{Cite web|url=http://www.arcella.nl/amoeba-proteus|title=''Amoeba proteus'' {{!}} Microworld|website=www.arcella.nl|access-date=2016-08-21|archive-url=https://web.archive.org/web/20160818214156/http://arcella.nl/amoeba-proteus|archive-date=18 August 2016|url-status=live}}</ref>
|220–760
|-
|''Chaos carolinense''<ref>{{Cite web|url=http://www.arcella.nl/chaos|title=''Chaos'' {{!}} Microworld|website=www.arcella.nl|access-date=2016-08-21|archive-url=https://web.archive.org/web/20161012224818/http://arcella.nl/chaos|archive-date=12 October 2016|url-status=live}}</ref>
|700–2000
|-
|''[[Biology:Pelomyxa|Pelomyxa palustris]]''<ref>{{Cite web|url=http://www.arcella.nl/pelomyxa-palustris|title=''Pelomyxa palustris'' {{!}} Microworld|website=www.arcella.nl|access-date=2016-08-21|archive-url=https://web.archive.org/web/20160818072933/http://arcella.nl/pelomyxa-palustris|archive-date=18 August 2016|url-status=live}}</ref>
|up to 5000
|-
|''[[Biology:Syringammina fragilissima|Syringammina fragilissima]]''{{r|gooday2011}}
|up to {{val|200000}}
|-
|}

==Amoebae as specialized cells and life cycle stages==
[[File:Neutrophil with anthrax copy.jpg|thumb|Neutrophil (white blood cell) engulfing anthrax bacteria]]
Some multicellular organisms have amoeboid cells only in certain phases of life, or use amoeboid movements for specialized functions. In the immune system of humans and other animals, amoeboid white blood cells pursue invading organisms, such as bacteria and pathogenic protists, and engulf them by [[Biology:Phagocytosis|phagocytosis]].<ref>{{cite journal |last1=Friedl |first1=Peter |last2=Borgmann |first2=Stefan |last3=Eva-B |first3=Bröcker |year=2001 |title=Amoeboid leukocyte crawling through extracellular matrix: lessons from the Dictyostelium paradigm of cell movement |journal=Journal of Leukocyte Biology |volume=70 |issue=4|pages=491–509 |doi=10.1189/jlb.70.4.491 |pmid=11590185 |s2cid=28731650 }}</ref>

Amoeboid stages also occur in the multicellular fungus-like protists, the so-called [[Biology:Slime mold|slime mould]]s. Both the plasmodial slime moulds, currently classified in the class [[Biology:Myxogastria|Myxogastria]], and the cellular slime moulds of the groups Acrasida and [[Biology:Dictyosteliida|Dictyosteliida]], live as amoebae during their feeding stage. The amoeboid cells of the former combine to form a giant [[Biology:Multinucleate|multinucleate]] organism,<ref>{{Cite journal|title=Intelligence: Maze-solving by an amoeboid organism|last=Nakagaki|date=2000|journal=Nature|doi=10.1038/35035159|pmid=11028990|volume=407|issue=6803|pages=470|display-authors=0|bibcode=2000Natur.407..470N|s2cid=205009141|doi-access=free}}</ref> while the cells of the latter live separately until food runs out, at which time the amoebae aggregate to form a multicellular migrating "slug" which functions as a single organism.<ref name=":0" />

Other organisms may also present amoeboid cells during certain life-cycle stages, e.g., the gametes of some green algae ([[Biology:Zygnematophyceae|Zygnematophyceae]])<ref>{{Cite book|title=Freshwater Algae of North America|url=https://archive.org/details/freshwateralgaen00shea|url-access=limited|last=Wehr|first=John D.|publisher=Academic Press|year=2003|isbn=978-0-12-741550-5|location=San Diego and London|pages=[https://archive.org/details/freshwateralgaen00shea/page/n369 353]}}</ref> and pennate diatoms,<ref>{{Cite web|url=http://rbg-web2.rbge.org.uk/algae/auxospores/lifecycle_sexual.html|title=Algae World: diatom sex and life cycles|access-date=1 March 2015|website=Algae World|publisher=Royal Botanic Garden Edinburgh|archive-url=https://web.archive.org/web/20140923102400/http://rbg-web2.rbge.org.uk/algae/auxospores/lifecycle_sexual.html|archive-date=23 September 2014|url-status=live}}</ref> the spores (or dispersal phases) of some [[Biology:Mesomycetozoea|Mesomycetozoea]],<ref>{{Cite journal|title=New species of Paramoebidium (trichomycetes, Mesomycetozoea) from the Mediterranean, with comments about the amoeboid cells in Amoebidiales|last=Valle|first=L.G.|date=2014|journal=Mycologia|doi=10.3852/13-153|pmid=24895422|volume=106|issue=3|pages=481–90|s2cid=3383757}}</ref><ref>Taylor, J. W. & Berbee, M. L. (2014). Fungi from PCR to Genomics: The Spreading Revolution in Evolutionary Biology. In: ''Systematics and Evolution''. Springer Berlin Heidelberg. p. 52, [https://books.google.com/books?id=SuZhBAAAQBAJ&pg=PA10] {{Webarchive|url=https://web.archive.org/web/20150630063053/https://books.google.com/books?id=SuZhBAAAQBAJ&lpg=PP1&hl=&pg=PA10|date=30 June 2015}}</ref> and the [[Biology:Sporoplasm|sporoplasm]] stage of [[Biology:Myxozoa|Myxozoa]] and of [[Biology:Ascetosporea|Ascetosporea]].<ref>{{cite journal |last1=Corliss |first1=J. O. |year=1987 |title=Protistan phylogeny and eukaryogenesis |url=https://books.google.com/books?id=oIbZPrCEvYwC |journal=International Review of Cytology |volume=100 |pages=319–370 |doi=10.1016/S0074-7696(08)61703-9 |pmid=3549607 |isbn=9780080586373 }}</ref>
{{Clear}}

==Amoebae as taxa==

===Early history and origins of Sarcodina===
[[File:Der Kleine Proteus from Roesel.jpg|thumb|250x250px|The first illustration of an amoeboid, from Roesel von Rosenhof's ''Insecten-Belustigung'' (1755)]]
[[File:Amoeba proteus with many pseudopodia.jpg|thumb|''Amoeba proteus''|250x250px]]
The earliest record of an amoeboid organism was produced in 1755 by August Johann Rösel von Rosenhof, who named his discovery "Der Kleine Proteus" ("the Little Proteus").<ref>Rosenhof, R. (1755). ''Monatlich herausgegebene Insektenbelustigungen'', vol. 3, p. 621, [https://books.google.com/books?id=q9JCAQAAMAAJ&pg=PA621] {{Webarchive|url=https://web.archive.org/web/20150713174920/https://books.google.com/books?id=q9JCAQAAMAAJ&hl=&pg=PA621|date=13 July 2015}}.</ref> Rösel's illustrations show an unidentifiable freshwater amoeba, similar in appearance to the common species now known as [[Biology:Amoeba proteus|Amoeba proteus]].<ref>{{Cite book|title=Biology of Amoeba|url=https://archive.org/details/biologyofamoeba0000jeon|url-access=registration|last=Jeon|first=Kwang W.|publisher=Academic Press |date=1973 |location=New York|pages=2–3, [https://books.google.com/books?id=J0vniMFGPukC&pg=PA2]|isbn=9780123848505}}</ref> The term "Proteus animalcule" remained in use throughout the 18th and 19th centuries, as an informal name for any large, free-living amoeboid.<ref>{{Cite book|title=Biological atlas: a guide to the practical study of plants and animals|url=https://archive.org/details/biologicalatlasg00mcal|last=McAlpine|first=Daniel|publisher=W. & A. K. Johnston |date=1881 |location=Edinburgh and London|pages=[https://archive.org/details/biologicalatlasg00mcal/page/17 17]}}</ref>

In 1822, the genus ''Amiba'' (from the [[Social:Ancient Greek|Greek]] ἀμοιβή ''amoibe'', meaning "change") was erected by the French naturalist Bory de Saint-Vincent.<ref>Bory de Saint-Vincent, J. B. G. M. "Essai d'une classification des animaux microscopiques." Agasse, Paris (1826).p. 28</ref><ref name="EOS1">{{cite book |editor1-first=Kimberley |editor1-last=McGrath |editor2-last=Blachford |editor2-first=Stacey |title=Gale Encyclopedia of Science Vol. 1: Aardvark-Catalyst |edition=2nd |date=2001 |isbn=978-0-7876-4370-6 |publisher=Gale Group |oclc=46337140 |url-access=registration |url=https://archive.org/details/galeencyclopedia0000mcgr }}</ref> Bory's contemporary, C. G. Ehrenberg, adopted the genus in his own classification of microscopic creatures, but changed the spelling to ''Amoeba''.<ref>Ehrenberg, Christian Gottfried. Organisation, systematik und geographisches verhältniss der infusionsthierchen: Zwei vorträge, in der Akademie der wissenschaften zu Berlin gehalten in den jahren 1828 und 1830. Druckerei der Königlichen akademie der wissenschaften, 1832. p. 59</ref>

In 1841, Félix Dujardin coined the term "''sarcode''" (from Greek σάρξ ''sarx'', "flesh," and εἶδος ''eidos'', "form") for the "thick, glutinous, homogeneous substance" which fills protozoan cell bodies.<ref>{{Cite book|title=Histoire Naturelle des Zoophytes Infusoires|url=https://archive.org/details/histoirenaturelle00duja|last=Dujardin|first=Felix|publisher=Librarie Encyclopedique de Roret |date=1841 |location=Paris|pages=[https://archive.org/details/histoirenaturelle00duja/page/26 26]}}</ref> Although the term originally referred to the protoplasm of any protozoan, it soon came to be used in a restricted sense to designate the gelatinous contents of amoeboid cells.<ref name="Pawlowski"/> Thirty years later, the Austrian zoologist Ludwig Karl Schmarda used "sarcode" as the conceptual basis for his division Sarcodea, a [[Biology:Phylum|phylum]]-level group made up of "unstable, changeable" organisms with bodies largely composed of "sarcode".<ref>{{Cite book|title=Zoologie|url=https://archive.org/details/zoologie00schmgoog|last=Schmarda|first=Ludwig Karl|publisher=W. Braumüller |date=1871 |pages=[https://archive.org/details/zoologie00schmgoog/page/n173 156]}}</ref> Later workers, including the influential taxonomist [[Biography:Otto Bütschli|Otto Bütschli]], amended this group to create the class Sarcodina,<ref>{{Cite book|title=Klassen und Ordnungen des Thier-Reichs I. Abteilung: Sarkodina und Sporozoa|last=Bütschli|first=Otto|publisher=Paleontologische Entwicklung der Rhisopoda von C. Scwager |date=1882 |pages=1}}</ref> a [[Biology:Taxon|taxon]] that remained in wide use throughout most of the 20th century.

Within the traditional Sarcodina, amoebae were generally divided into [[Biology:Morphology|morphological categories]], on the basis of the form and structure of their pseudopods. Amoebae with pseudopods supported by regular arrays of [[Biology:Microtubule|microtubule]]s (such as the freshwater Heliozoa and marine [[Biology:Radiolaria|Radiolaria]]) were classified as Actinopoda; whereas those with unsupported pseudopods were classified as Rhizopoda.<ref>{{Cite book|title=Protozoölogy|url=https://archive.org/details/in.ernet.dli.2015.166964|last=Calkins|first=Gary N.|publisher=Lea & Febiger |date=1909 |location=New York|pages=[https://archive.org/details/in.ernet.dli.2015.166964/page/n106 38]–40}}</ref> The Rhizopods were further subdivided into lobose, filose, and reticulose amoebae, according to the morphology of their pseudopods.

===Dismantling of Sarcodina===
In the final decade of the 20th century, a series of molecular phylogenetic analyses confirmed that Sarcodina was not a [[Biology:Monophyletic|monophyletic]] group. In view of these findings, the old scheme was abandoned and the amoebae of Sarcodina were dispersed among many other high-level taxonomic groups. Today, the majority of traditional sarcodines are placed in two eukaryote [[Biology:Kingdom#Eukaryotic supergroups|supergroups]]: [[Biology:Amoebozoa|Amoebozoa]] and [[Biology:Rhizaria|Rhizaria]]. The rest have been distributed among the [[Biology:Excavata|excavates]], opisthokonts, and stramenopiles. Some, like the Centrohelida, have yet to be placed in any supergroup.<ref name="Pawlowski"/><ref>{{Cite journal|title=The Revised Classification of Eukaryotes|last=Adl|first=Sina M.|date=2012|journal=Journal of Eukaryotic Microbiology|doi=10.1111/j.1550-7408.2012.00644.x|pmid=23020233|display-authors=0|volume=59|issue=5|pages=429–93|pmc=3483872}}</ref>

===Classification===
Recent classification places the various amoeboid genera in the following groups:

{|class="wikitable"
|-
! Supergroups
! Major groups and genera
! Morphology
|- 
|[[Biology:Amoebozoa|Amoebozoa]]
|
* '''[[Biology:Tubulinea|Tubulinea]]''' (formerly part of [[Biology:Lobosa|Lobosa]])
** [[Biology:Amoeba (genus)|Amoeba]], Chaos, Hydramoeba, Metachaos, [[Biology:Trichamoeba|Trichamoeba]], [[Biology:Glaeseria|Glaeseria]], [[Biology:Hartmannella|Hartmannella]],[[Biology:Polychaos|Polychaos]], Saccamoeba, [[Biology:Flabellula|Flabellula]], [[Biology:Gephyramoeba|Gephyramoeba]], [[Biology:Leptomyxa|Leptomyxa]],  [[Biology:Rhizamoeba|Rhizamoeba]], [[Biology:Trichosphaerium|Trichosphaerium]], Echinamoeba,
* '''[[Biology:Discosea|Discosea]]''' (formerly part of Lobosa)
** ''[[Biology:Acanthamoeba|Acanthamoeba]], [[Biology:Protoacanthamoeba|Protoacanthamoeba]], Balamuthia, [[Biology:Discamoeba|Discamoeba]], [[Biology:Clydonella|Clydonella]], [[Biology:Hollandella|Hollandella]],  [[Biology:Korotnevella|Korotnevella]] (Dactylamoeba),  [[Biology:Lingulamoeba|Lingulamoeba]],  [[Biology:Mayorella|Mayorella]], [[Biology:Neoparamoeba|Neoparamoeba]], [[Biology:Paramoeba|Paramoeba]], [[Biology:Platyamoeba|Platyamoeba]],  [[Biology:Sappinia|Sappinia]],  [[Biology:Thecamoeba|Thecamoeba]], [[Biology:Unda (genus)|Unda]], [[Biology:Vannella|Vannella]], [[Biology:Vexillifera|Vexillifera]]''
*[[Biology:Conosa|Conosa]]: 
** ''[[Biology:Endamoeba|Endamoeba]]'', ''[[Biology:Entamoeba|Entamoeba]]'', Filamoeba, ''[[Biology:Iodamoeba|Iodamoeba]]'', ''[[Biology:Mastigamoeba|Mastigamoeba]]'', Mastigina, Phreatamoeba,''[[Biology:Mastigella|Mastigella]]'', ''[[Biology:Pelomyxa|Pelomyxa]]'', ''[[Biology:Dictyostelium|Dictyostelium]]'', ''[[Biology:Physarum|Physarum]]''
* ''incertae sedis''
**  Stereomyxa
|valign=top|
* Lobose pseudopods ([[Biology:Lobosa|Lobosa]]) are blunt, and there may be one or several on a cell, which is usually divided into a layer of clear ectoplasm surrounding more granular endoplasm.
|- 
|[[Biology:Rhizaria|Rhizaria]]
|valign=top|
* [[Biology:Cercozoa|Cercozoa]]:
**'''[[Biology:Filosa|Filosa]]''':
***'''[[Biology:Monadofilosa|Monadofilosa]]''': ''[[Biology:Gyromitus|Gyromitus]]'', ''[[Biology:Paulinella|Paulinella]]''
***'''[[Biology:Granofilosea|Granofilosea]]'''
***[[Biology:Chlorarachniophyceae|Chlorarachniophyceae]]
**'''[[Biology:Endomyxa|Endomyxa]]''':
***[[Biology:Proteomyxidea|Proteomyxidea]]: orders [[Biology:Aconchulinida|Aconchulinida]], Pseudosporida, [[Biology:Reticulosida|Reticulosida]]
***[[Biology:Gromiidea|Gromiidea]]
* [[Biology:Foraminifera|Foraminifera]]
* [[Biology:Radiolaria|Radiolaria]]
|valign=top|
* Filose pseudopods ([[Biology:Filosa|Filosa]]) are narrow and tapering. The vast majority of filose amoebae, including all those that produce shells, are placed within the [[Biology:Cercozoa|Cercozoa]] together with various flagellates that tend to have amoeboid forms. The naked filose amoebae also includes vampyrellids.
* Reticulose pseudopods ([[Biology:Endomyxa|Endomyxa]]) are cytoplasmic strands that branch and merge to form a net. They are found most notably among the [[Biology:Foraminifera|Foraminifera]], a large group of marine protists that generally produce multi-chambered shells. There are only a few sorts of naked reticulose amoebae, notably the gymnophryids, and their relationships are not certain.
* [[Biology:Radiolaria|Radiolaria]]ns are a subgroup of actinopods that are now grouped with rhizarians.
|- 
|[[Biology:Excavata|Excavata]]
|valign=top|
* '''Heterolobosea''':
**[[Biology:Vahlkampfiidae|Vahlkampfiidae]]: ''[[Biology:Monopylocystis|Monopylocystis]]'', ''[[Biology:Naegleria|Naegleria]]'', ''[[Biology:Neovahlkampfia|Neovahlkampfia]]'', ''[[Biology:Paratetramitus|Paratetramitus]]'', ''[[Biology:Paravahlkampfia|Paravahlkampfia]]'', ''[[Biology:Protonaegleria|Protonaegleria]]'', ''[[Biology:Psalteriomonas|Psalteriomonas]]'', ''[[Biology:Sawyeria|Sawyeria]]'', ''[[Biology:Tetramitus|Tetramitus]]'', ''[[Biology:Vahlkampfia|Vahlkampfia]]'', ''[[Biology:Willaertia|Willaertia]]''
**[[Biology:Gruberellidae|Gruberellidae]]: ''Gruberella'', ''[[Biology:Stachyamoeba|Stachyamoeba]]''
*Parabasalidea: ''Dientamoeba'', ''Histomonas''
*Other: ''[[Biology:Rosculus|Rosculus]]'', ''Acrasis'', ''Heteramoeba'', ''Learamoeba'', ''Stygamoeba'', ''Plaesiobystra'',<ref name="Park2009">{{Cite journal |last1=Park |first1=J. S. |last2=Simpson |first2=A. G. B. |last3=Brown |first3=S. |last4=Cho |first4=B. C. |title=Ultrastructure and Molecular Phylogeny of two Heterolobosean Amoebae, Euplaesiobystra hypersalinica gen. Et sp. Nov. And Tulamoeba peronaphora gen. Et sp. Nov., Isolated from an Extremely Hypersaline Habitat |doi=10.1016/j.protis.2008.10.002 |journal=Protist |volume=160 |issue=2 |pages=265–283 |date=2009 |pmid=19121603}}</ref> ''Tulamoeba''<ref name="Park2009" />
|valign=top|
* The Heterolobosea, includes protists that can transform between amoeboid and [[Biology:Flagellate|flagellate]] forms.
|-
|Heterokonta
|valign=top|
* [[Biology:Chrysophyceae|Chrysophyceae]]: ''Chrysamoeba'', ''Rhizochrysis''
* [[Biology:Xanthophyceae|Xanthophyceae]]: ''Rhizochloris''
* [[Biology:Labyrinthulomycetes|Labyrinthulomycetes]]
|
* The heterokont chrysophyte and xanthophyte algae include some amoeboid members, the latter being poorly studied.<ref>Ott, Donald W., Carla K. Oldham-Ott, Nataliya Rybalka, and Thomas Friedl. 2015. Xanthophyte, Eustigmatophyte, and Raphidophyte Algae. In: Wehr, J.D., Sheath, R.G., Kociolek, J.P. (Eds.) ''Freshwater Algae of North America: Ecology and Classification'', 2nd edition. Academic Press, Amsterdam, pp. 483–534, [https://books.google.com/books?id=yjnLAwAAQBAJ] {{Webarchive|url=https://web.archive.org/web/20170122104643/https://books.google.com/books?id=yjnLAwAAQBAJ|date=22 January 2017}}.</ref>
|-
|Alveolata
|valign=top|
* [[Biology:Dinoflagellate|Dinoflagellata]]: ''[[Biology:Oodinium|Oodinium]]'', ''[[Biology:Pfiesteria|Pfiesteria]]''
|
* Parasite with amoeboid life cycle stages.
|- 
|[[Biology:Opisthokont|Opisthokont]]a
|valign=top|
* Nucleariida: ''[[Biology:Micronuclearia|Micronuclearia]]'', ''[[Biology:Nuclearia|Nuclearia]]''
|valign=top|
* Nucleariids appear to be close relatives of animals and [[Biology:Fungus|fungi]].
|-
|{{vanchor|Ungrouped}}/<br />unknown
|valign=top|
* ''Adelphamoeba'', ''Astramoeba'', ''Dinamoeba'', ''Flagellipodium'', ''Flamella'', ''Gibbodiscus'', ''Gocevia'', ''Malamoeba'', ''Nollandia'', ''Oscillosignum'', ''Paragocevia'', ''[[Biology:Parvamoeba|Parvamoeba]]'', ''Pernina'', ''Pontifex'', ''Pseudomastigamoeba'', ''Rugipes'', ''Striamoeba'', ''Striolatus'', ''Subulamoeba'', ''Theratromyxa'', ''Trienamoeba'', ''Trimastigamoeba'', and over 40 other genera<ref>Patterson, D. J.; Simpson, A. G. B.; Rogerson, A. (2000). "Amoebae of uncertain affinities". In: Lee, J. J.; Leedale, G. F.; Bradbury, P. ''An Illustrated Guide to the Protozoa'', 2nd ed., Vol. 2, p. 804-827. Lawrence, Kansas: Society of Protozoologists/Allen Press. [https://species.wikimedia.org/wiki/Incertae_sedis_Eukaryota#Patterson.2C_Simpson.2C_.26_Rogerson.2C_in_Lee_et_al._.282000.29] {{Webarchive|url=https://web.archive.org/web/20160308194141/https://species.wikimedia.org/wiki/Incertae_sedis_Eukaryota#Patterson.2C_Simpson.2C_.26_Rogerson.2C_in_Lee_et_al._.282000.29 |date=8 March 2016}}. Genera considered ungrouped/unknown by this source in 2000 but which have since become classified have been moved to those classifications on Wikipedia.</ref>
|
|}

Some of the amoeboid groups cited (e.g., part of chrysophytes, part of xanthophytes, [[Biology:Chlorarachniophyte|chlorarachniophyte]]s) were not traditionally included in Sarcodina, being classified as [[Biology:Algae|algae]] or [[Biology:Flagellate|flagellate]]d protozoa.

==Pathogenic interactions with other organisms==
[[File:Trophozoites of Entamoeba histolytica with ingested erythrocytes.JPG|thumb|[[Biology:Trophozoite|Trophozoite]]s of the pathogenic ''Entamoeba histolytica'' with ingested red blood cells]]

Some amoebae can infect other organisms [[Biology:Pathogen|pathogen]]ically, causing disease:<ref>Casadevall A (2008) Evolution of intracellular pathogens. Annu Rev Microbiol 62: 19–33. 10.1146/annurev.micro.61.080706.093305 [PubMed] [CrossRef] [Google Scholar]</ref><ref>Guimaraes AJ, Gomes KX, Cortines JR, Peralta JM, Peralta RHS (2016) Acanthamoeba spp. as a universal host for pathogenic microorganisms: One bridge from environment to host virulence. Microbiological Research 193: 30–38. 10.1016/j.micres.2016.08.001 [PubMed] [CrossRef] [Google Scholar]</ref><ref>Hilbi H, Weber SS, Ragaz C, Nyfeler Y, Urwyler S (2007) Environmental predators as models for bacterial pathogenesis. Environmental microbiology 9: 563–575. 10.1111/j.1462-2920.2007.01238.x [PubMed] [CrossRef] [Google Scholar]</ref><ref>{{cite journal |last1=Greub |first1=G |last2=Raoult |first2=D |year=2004 |title=Microorganisms resistant to free-living amoebae |journal=Clinical Microbiology Reviews |volume=17 |issue=2 |pages=413–433 |doi=10.1128/CMR.17.2.413-433.2004 |pmid=15084508 |pmc=387402 |doi-access=free }}</ref>

*''[[Biology:Entamoeba histolytica|Entamoeba histolytica]]'' is the cause of [[Medicine:Amoebiasis|amoebiasis]], or amoebic dysentery.
*''[[Biology:Naegleria fowleri|Naegleria fowleri]]'' (the "brain-eating amoeba") is a fresh-water-native species that can be fatal to humans if introduced through the nose.
*''[[Biology:Acanthamoeba|Acanthamoeba]]'' can cause amoebic [[Medicine:Keratitis|keratitis]] and [[Medicine:Encephalitis|encephalitis]] in humans.
*''[[Biology:Balamuthia mandrillaris|Balamuthia mandrillaris]]'' is the cause of (often fatal) granulomatous amoebic meningoencephalitis.

Amoeba have been found to harvest and grow the bacteria implicated in [[Medicine:Plague (disease)|plague]].<ref>{{Cite web|url=https://www.sciencedaily.com/releases/2018/01/180116144229.htm|title = Are amoebae safe harbors for plague? New research shows that plague bacteria not only survive, but thrive and replicate once ingested by an amoeba}}</ref> Amoebae can likewise play host to microscopic organisms that are pathogenic to people and help in spreading such microbes. Bacterial pathogens (for example, ''[[Biology:Legionella|Legionella]]'') can oppose absorption of food when devoured by amoebae.{{r|vid2016}}
The currently generally utilized and best-explored amoebae that host other organisms are Acanthamoeba castellanii and Dictyostelium discoideum.<ref>{{Cite journal |doi=10.3389/fcimb.2019.00047|pmid=30941316|title=Editorial: Amoebae as Host Models to Study the Interaction with Pathogens |year=2019|last1=Thewes|first1=Sascha|last2=Soldati|first2=Thierry|last3=Eichinger |first3=Ludwig|journal=Frontiers in Cellular and Infection Microbiology|volume=9|doi-access=free|pmc=6433779|page=47}}</ref>
Microorganisms that can overcome the defenses of one-celled organisms can shelter and multiply inside them, where they are shielded from unfriendly outside conditions by their hosts.

==Meiosis==
Recent evidence indicates that several Amoebozoa lineages undergo [[Biology:Meiosis|meiosis]].

[[Biology:Homology#Orthology|Orthologs]] of genes employed in [[Biology:Meiosis|meiosis]] of sexual [[Biology:Eukaryote|eukaryote]]s have recently been identified in the ''[[Biology:Acanthamoeba|Acanthamoeba]]'' [[Biology:Genome|genome]]. These genes included ''[[Biology:Spo11|Spo11]], Mre11, Rad50, [[Biology:RAD51|Rad51]], Rad52, Mnd1, [[Biology:DMC1 (gene)|Dmc1]], [[Biology:MSH2|Msh]]'' and ''Mlh''.<ref name="pmid25800982">{{cite journal |vauthors=Khan NA, Siddiqui R |title=Is there evidence of sexual reproduction (meiosis) in Acanthamoeba? |journal=Pathog Glob Health |volume=109 |issue=4 |pages=193–5 |year=2015 |pmid=25800982 |doi=10.1179/2047773215Y.0000000009 |pmc=4530557 }}</ref> This finding suggests that the ‘'Acanthamoeba'’ are capable of some form of meiosis and may be able to undergo sexual reproduction.

The meiosis-specific [[Biology:Recombinase|recombinase]], [[Biology:DMC1 (gene)|Dmc1]], is required for efficient meiotic [[Biology:Homologous recombination|homologous recombination]], and ''Dmc1'' is expressed in ''[[Biology:Entamoeba histolytica|Entamoeba histolytica]]''.<ref name=Kelso>{{cite journal |vauthors=Kelso AA, Say AF, Sharma D, Ledford LL, Turchick A, Saski CA, King AV, Attaway CC, Temesvari LA, Sehorn MG |title=Entamoeba histolytica Dmc1 Catalyzes Homologous DNA Pairing and Strand Exchange That Is Stimulated by Calcium and Hop2-Mnd1 |journal=PLOS ONE |volume=10 |issue=9 |pages=e0139399 |year=2015 |pmid=26422142 |pmc=4589404 |doi=10.1371/journal.pone.0139399 |bibcode=2015PLoSO..1039399K |doi-access=free }}</ref> The purified Dmc1 from ''E. histolytica'' forms [[Biology:Synapsis|presynaptic]] filaments and catalyses [[Chemistry:Adenosine triphosphate|ATP]]-dependent [[Biology:Homologous recombination|homologous DNA pairing]] and DNA strand exchange over at least several thousand base pairs.<ref name=Kelso /> The DNA pairing and strand exchange reactions are enhanced by the eukaryotic meiosis-specific recombination accessory factor (heterodimer) Hop2-Mnd1.<ref name=Kelso /> These processes are central to meiotic recombination, suggesting that ''E. histolytica'' undergoes meiosis.<ref name=Kelso />

Studies of ''[[Biology:Entamoeba invadens|Entamoeba invadens]]'' found that, during the conversion from the tetraploid uninucleate [[Apicomplexan life cycle#Glossary of cell types|
trophozoite]] to the tetranucleate cyst, [[Biology:Homologous recombination|homologous recombination]] is enhanced.<ref name=Singh>{{cite journal |vauthors=Singh N, Bhattacharya A, Bhattacharya S |title=Homologous recombination occurs in Entamoeba and is enhanced during growth stress and stage conversion |journal=PLOS ONE |volume=8 |issue=9 |pages=e74465 |year=2013 |pmid=24098652 |pmc=3787063 |doi=10.1371/journal.pone.0074465 |bibcode=2013PLoSO...874465S |doi-access=free }}</ref> Expression of genes with functions related to the major steps of meiotic recombination also increase during encystations.<ref name=Singh /> These findings in ''E. invadens'', combined with evidence from studies of ''E. histolytica'' indicate the presence of meiosis in the ''Entamoeba''.

''[[Biology:Dictyostelium discoideum|Dictyostelium discoideum]]'' in the supergroup [[Biology:Amoebozoa|Amoebozoa]] can undergo mating and [[Biology:Sexual reproduction|sexual reproduction]] including meiosis when food is scarce.<ref name="pmid20617172">{{cite journal |vauthors=Flowers JM, Li SI, Stathos A, Saxer G, Ostrowski EA, Queller DC, Strassmann JE, Purugganan MD |title=Variation, sex, and social cooperation: molecular population genetics of the social amoeba Dictyostelium discoideum |journal=PLOS Genet. |volume=6 |issue=7 |pages=e1001013 |year=2010 |pmid=20617172 |pmc=2895654 |doi=10.1371/journal.pgen.1001013 |doi-access=free }}</ref><ref name="pmid21929567">{{cite journal |vauthors=O'Day DH, Keszei A |title=Signalling and sex in the social amoebozoans |journal=Biol Rev Camb Philos Soc |volume=87 |issue=2 |pages=313–29 |year=2012 |pmid=21929567 |doi=10.1111/j.1469-185X.2011.00200.x |s2cid=205599638 }}</ref>

Since the Amoebozoa diverged early from the eukaryotic family tree, these results suggest that meiosis was present early in eukaryotic evolution. Furthermore, these findings are consistent with the proposal of Lahr et al.<ref name="pmid21429931">{{cite journal |vauthors=Lahr DJ, Parfrey LW, Mitchell EA, Katz LA, Lara E |title=The chastity of amoebae: re-evaluating evidence for sex in amoeboid organisms |journal=Proc. Biol. Sci. |volume=278 |issue=1715 |pages=2081–90 |year=2011 |pmid=21429931 |pmc=3107637 |doi=10.1098/rspb.2011.0289 }}</ref> that the majority of amoeboid lineages are anciently sexual.

==References==
{{Reflist|refs=
<ref name=gooday2011>{{Cite journal|last1=Gooday|first1=A. J.|last2=Aranda da Silva|first2=A.|last3=Pawlowski|first3=J.|date=2011-12-01|title=Xenophyophores (Rhizaria, Foraminifera) from the Nazaré Canyon (Portuguese margin, NE Atlantic)|journal=Deep-Sea Research Part II: Topical Studies in Oceanography|series=The Geology, Geochemistry, and Biology of Submarine Canyons West of Portugal|volume=58|issue=23–24|pages=2401–2419|doi=10.1016/j.dsr2.2011.04.005|bibcode=2011DSRII..58.2401G}}</ref>
<ref name=vid2016>{{cite web |first=Aparna |last=Vidyasagar |date=April 2016 |title=What Is an Amoeba? |url=https://www.livescience.com/54281-amoeba-definition.html |website=livescience.com |access-date=8 November 2020 |language=en}}</ref>
}}

==Further reading==
*Walochnik, J. & Aspöck, H. (2007). [http://www.zobodat.at/pdf/DENISIA_0020_0323-0350.pdf Amöben: Paradebeispiele für Probleme der Phylogenetik, Klassifikation und Nomenklatur]. ''Denisia'' 20: 323–350. (In German)
*[http://tolweb.org/notes/?note_id=51 Amoebae: Protists Which Move and Feed Using Pseudopodia] at the Tree of Life web project
* Pawlowski, J. & Burki, F. (2009). [https://web.archive.org/web/20150923204916/http://www.cmde.science.ubc.ca/pdf/09PawlowskiTCS.pdf Untangling the Phylogeny of Amoeboid Protists]. ''Journal of Eukaryotic Microbiology'' 56.1: 16–25.

==External links==
{{NIE Poster|Rhizopoda}}
* Siemensma, F. [http://www.arcella.nl/ Microworld: world of amoeboid organisms].
* Völcker, E. & Clauß, S. [http://www.penard.de/Key/ Visual key to amoeboid morphotypes]. Penard Labs.
*[https://web.archive.org/web/20090610035748/http://www.bms.ed.ac.uk/research/others/smaciver/amoebae.htm The Amoebae] website of Maciver Lab of the University of Edinburgh, brings together information from published sources.
*[http://micro.magnet.fsu.edu/moviegallery/pondscum/protozoa/amoeba/index.html Molecular Expressions Digital Video Gallery: Pond Life – Amoeba (Protozoa)] – informative amoeba videos

{{Protozoa protist}}
{{Eukaryota classification}}

[[Category:Amoeboids|*]]
[[Category:Cell biology]]
[[Category:Motile cells]]

{{Sourceattribution|Amoeba}}