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Clockwise from top right: Amoeba proteus, Actinophrys sol, Acanthamoeba sp., Nuclearia thermophila., Euglypha acanthophora, neutrophil ingesting bacteria. An amoeba (/ ə ˈ m iː b ə /; less commonly spelled ameba or amœba; pl.: amoebas (less commonly, amebas) or amoebae (amebae) / ə ˈ m iː b i /), [1] often called an amoeboid, is a type of cell or unicellular organism with the ability ...
Amoebozoa vary greatly in size. Some are only 10–20 μm in diameter, while others are among the largest protozoa. The well-known species Amoeba proteus, which may reach 800 μm in length, is often studied in schools and laboratories as a representative cell or model organism, partly because of its convenient size.
Food enveloped by the Amoeba is stored in digestive organelles called food vacuoles. Amoeba, like other unicellular eukaryotic organisms, reproduces asexually by mitosis and cytokinesis. Sexual phenomena have not been directly observed in Amoeba, although sexual exchange of genetic material is known to occur in other Amoebozoan groups. [15]
Some modern authors prefer to exclude multicellular organisms from the traditional definition of a protist, restricting protists to unicellular organisms. [ 9 ] [ 10 ] This more constrained definition excludes all brown , the multicellular red and green algae , and, sometimes, slime molds (slime molds excluded when multicellularity is defined ...
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 "one-celled animals".
The kingdom-level classification of life is still widely employed as a useful way of grouping organisms, notwithstanding some problems with this approach: Kingdoms such as Protozoa represent grades rather than clades, and so are rejected by phylogenetic classification systems.
The heterolobosean pathogen Naegleria fowleri can behave as an amoeba (center) or as a flagellate (right). An amoeboflagellate ( pl. amoeboflagellates ) is any eukaryotic organism capable of behaving as an amoeba and as a flagellate at some point during their life cycle.
Amoeba proteus is a large species of amoeba closely related to another genus of giant amoebae, Chaos. As such, the species is sometimes given the alternative scientific name Chaos diffluens. [1] [2] Amoeba proteus in locomotion. This protozoan uses extensions called pseudopodia to move and to eat smaller unicellular organisms.