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Amoeba

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Amoeboids include a wide variety of completely unrelated free-living and parasitic groups. Amoebae move and feed via cellular projections called pseudopods, which are divided into rhizopods (unsupported) and actinopods (supported by rigid microtubules).


Lobose amoebae are forms with broad, blunt rhizopods. They may either have a single pseudopod at the front or many branching outwards. They move by flowing into the pseudopod and feed by physically engulfing other objects, trapping them in vacuoles. Forms include:


  • GenusPelomyxa, the giant amoeba (up to 1 mm!)
  • TaxonRamicristates, including most of the familiar amoebae
  • TaxonEntamoebae, various parasitic amoebae


Filose amoebae include forms with fine, branching rhizopods. TaxonGranuloreticulosa has members with rhizopods that form a network, and include the well-known shelled Foraminifera.


The actinopod amoebae are divided into the Radiolaria, marine mostly shelled forms, and Heliozoa, which are mostly-fresh water and naked. Pseudopods take the form of rigid spikes that collect food and aid in buoyancy. Some heliozoans move by rolling along the substrate. Radiolarian forms include:


  • TaxonPhaeodarea
  • TaxonPolycystinea
  • TaxonAcantharea


and heliozoan forms include:


  • TaxonActinophryida
  • TaxonCentrohelida


Also worth mentioning is the TaxonXenophyophorea, which includes various giant marine forms. All of these are classified under the KingdomProtista.