Amoeba (Chaos diffluens)

Foraminiferan (Ammonia tepida)

Heliozoan (Actinophrys sol)

Amoeboids are cells that move or feed by means of temporary projections, called pseudopods (false feet). They have appeared in a number of different groups. Some cells in multicellular animals may be amoeboid, for instance human white blood cells, which consume pathogens. Many protists exist as individual amoeboid cells, or take such a form at some point in their life-cycle. The most famous such organism is Amoeba proteus; the name amoeba is variously used to describe its close relatives, other organisms similar to it, or the amoeboids in general. Chaos diffluens, an amoeba. ... Chaos diffluens, an amoeba. ... ImageMetadata File history File links Live_Ammonia_tepida. ... ImageMetadata File history File links Live_Ammonia_tepida. ... Actinophrys sol, a common heliozoan. ... Actinophrys sol, a common heliozoan. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Pseudopods or pseudopodia (false feet) are temporary projections of eukaryotic cells. ... White Blood Cells redirects here. ... Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all... For other uses, see Amoeba (disambiguation). ...

Amoeboids may be divided into several morphological categories based on the form and structure of the pseudopods. Those where the pseudopods are supported by regular arrays of microtubules are called actinopods, and forms where they are not are called rhizopods, further divided into lobose, filose, and reticulose amoebae. There is also a strange group of giant marine amoeboids, the xenophyophores, that do not fall into any of these categories. Microtubules are one of the components of the cytoskeleton. ... Orders Psamminida Stannomida Xenophyophores are marine protozoans, giant single-celled organisms found throughout the worlds oceans, but in their greatest numbers on the abyssal plains of the deep ocean. ...

• Lobose pseudopods 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. Most, including Amoeba itself, move by the body mass flowing into an anterior pseudopod. The vast majority form a monophyletic group called the Amoebozoa, which also includes most slime moulds. A second group, the Percolozoa, includes protists that can transform between amoeboid and flagellate forms.

• Filose pseudopods are narrow and tapering. The vast majority of filose amoebae, including all those that produce shells, are placed within the Cercozoa together with various flagellates that tend to have amoeboid forms. The naked filose amoebae comprise two other groups, the vampyrellids and nucleariids. The latter appear to be close relatives of animals and fungi.

• Reticulose pseudopods are cytoplasmic strands that branch and merge to form a net. They are found most notably among the Foraminifera, a large group of marine protists that generally produce multi-chambered shells. There are only a few sorts of naked reticulose amoeboids, notably the gymnophryids, and their relationships are not certain.

• Actinopods are divided into the radiolaria and heliozoa. The radiolaria are mostly marine protists with complex internal skeletons, including central capsules that divide the cells into granular endoplasm and frothy ectoplasm that keeps them buoyant. The heliozoa include both freshwater and marine forms that use their axopods to capture small prey, and only have simple scales or spines for skeletal elements. Both groups appear to be polyphyletic.

Traditionally the amoeboid protozoa are grouped together as the Sarcodina, variously ranked from class to phylum, with each of the above categories as a formal subtaxon. However, since they are all based on form rather than phylogeny, newer systems generally separate some out or abandon them entirely. Most amoeboids are now included in two major supergroups - the Amoebozoa, including most lobose amoebae and slime moulds, and the Rhizaria, including the Cercozoa, Foraminifera, radiolarian classes and certain heliozoa. However, amoeboids have appeared separately in many other groups, including various different lines of algae not listed above. Subgroups Mycetozoa(slime moulds) Archamoebae    Pelobiontida    Entamoebida Gymnamoebia Various others The Amoebozoa are a major group of amoeboid protozoa, including the majority that move by means of internal cytoplasmic flow. ... Typical orders Protostelia Protosteliida Myxogastria Liceida Echinosteliida Trichiida Stemonitida Physarida Dictyostelia Dictyosteliida Slime (or slime mold) is a broad term often referring to roughly six groups of Eukaryotes. ... The Percolozoa are a group of colorless protists including many that can transform between amoeboid, flagellate, and encysted stages, collectively referred to as schizopyrenids or amoeboflagellates. ... Flagellata from Ernst Haeckels Artforms of Nature, 1904 Parasitic excavate (Giardia lamblia) Green alga (Chlamydomonas) Flagellates are cells with one or more whip-like organelles called flagella. ... The Cercozoa are a group of protists, including most amoeboids and flagellates that feed by means of filose pseudopods. ... A small group of protists with filose pseudopods and lacking shells. ... The nucleariids are a small group of amoebae with filose pseudopods, known mostly from soils and freshwater. ... For other uses, see Animal (disambiguation). ... For the fictional character, see Fungus the Bogeyman. ... Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida - extinct Lagenida Miliolida Robertinida Rotaliida Silicoloculinida Spirillinida Textulariida incertae sedis    Xenophyophorea    Reticulomyxa The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ... The gymnophryids are a small group of amoeboids that lack shells and produce thin, reticulose pseudopods. ... Possible classes Polycystinea Acantharea Taxopodea Radiolaria are amoeboid protozoa that produce intricate mineral skeletons, typically with a central capsule dividing the cell into inner and outer portions, called endoplasm and ectoplasm. ... Heliozoa, or sun animalcules, are roughly spherical amoeboids with many stiff, microtubule-supported projections called axopods radiating outward from the cell surface. ... In biology, a taxon is polyphyletic if it is descended from more than one root form (in Greek poly = many and phyletic = racial). ... Subgroups Mycetozoa(slime moulds) Archamoebae    Pelobiontida    Entamoebida Gymnamoebia Various others The Amoebozoa are a major group of amoeboid protozoa, including the majority that move by means of internal cytoplasmic flow. ... Phyla Cercozoa Foraminifera Radiolaria The Rhizaria are a major line of protists. ...

Sub-phylum Sarcodina

Amoeboids are classified in a sub-phylum called sarcodina. Basically, amoeboids move by moving their cytoplasm, resembling limbs, to move around and engulf food particles with its cytoplasm. Some amoeba may form a glass covering around and over its normal amoeba body. When these protozoan die, their glass stays in tact as the cytoplasm gradually dies. These glass particles then accumulate and are use to make many products, such as the luminosity of road paint, or the grit in toothpaste. Amoeboids mainly consist of contractile vacuoles, a nucleus, and cytoplasm as their basic structure. As the cytoplasm surrounds the prey, it injects enzymes into the organism, thus digesting their prey. Cross section of cell with cytoplasm labeled at center right. ... Figure 1: A paramecium. ... HeLa cells stained for DNA with the Blue Hoechst dye. ... Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ...

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External links

• The Amoebae website brings together information from published sources.
• Amoebas are more than just blobs
• sun animacules and amoebas
• Molecular Expressions Digital Video Gallery: Pond Life - Amoeba (Protozoa) Some good, informative Amoeba videos.
• Joseph Leidy's Amoeba Plates