Amoeboids

An Amoeba (/əˈmiːbə/; rarely spelled amœba, US English rarely spelled ameba; plural am(o)ebas or am(o)ebae /əˈmiːbiː/), often called amoeboid, is a type of cell or organism which has the ability to alter its shape, primarily by extending and retracting pseudopods. Specifically, the amoeba moves by extending a pseudopod (a process known as “ballooning”), attaching it to the substrate and filling it with cytosol and releasing its rear portion from attachment to the substrate which results in the organism being propelled forward. Amoebas do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.

Microbiologists often use the terms "amoeboid" and "amoeba" interchangeably for any organism that exhibits amoeboid movement.

In older classification systems, most amoebas were placed in the class or subphylum Sarcodina, a grouping of single-celled organisms that possess pseudopods or move by protoplasmic flow. However, molecular phylogenetic studies have shown that Sarcodina is not a monophyletic group whose members share common descent. Consequently, amoeboid organisms are no longer classified together in one group.

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