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a subclass of protozoans capable of forming temporary cytoplasmic protuberances, or pseudopods, which serve for movement and for capturing food (certain amoebas, as well as rhizopod gametes, form temporary flagella). The pseudo-pods may be lobate, filamentous, or radial, and they may undergo anastomosis to form nets.

The rhizopods range in size from a few microns to 3 mm (in extant species; in fossil nummulites, to 5 mm). The body consists of a transparent surface layer, or ectoplasm, and a granular inner layer, or endoplasm. The endoplasm contains a nucleus. There are five orders of Rhizopoda: (1) Amoebida, widely distributed in fresh and marine waters and in the soil (the genus Entamoeba is a parasite in the human and animal intestine); (2) Testacea, inhabitants of fresh waters; (3) Foraminifera, marine, mostly benthic (occasionally pelagic) forms with a complex life cycle that alternates sexual and asexual reproduction; (4) Heliozoa, freshwater; and (5) Radiolaria, found only in the oceans. The shells of rhizopods, which are well preserved in fossil form, are widely used in stratigraphy.


References in periodicals archive ?
On the occurrence of testate amoebae (Protozoa, Rhizopoda) in Brazilian inland waters.
First records of testate amoebae (Protozoa: Rhizopoda) from Mount Buffalo National Park, Victoria.
Study of testacean assemblages (Protozoa: Rhizopoda) in touristic waterfall regions of Chapada dos Guimaraes National Park, Mato Grosso State, Brazil.
Amebas testaceas (Protista, Sarcomastigophora, Rhizopoda) em Sphagnum recurvo P.Beauev e Sphagnum perichartiale Hampe (turfeira), no municipio de Sao Francisco de Paula, Rio Grande do Sul, Brasil.
The abundance and micro-distribution of testate amoebae (Rhizopoda: Testaceae) in Sphagnum.
The preparation of testate amoebae (Protozoa: Rhizopoda) samples from peat.
Testate amoebae (Protozoa, Rhizopoda) associated to littoral aquatic macrophytes in a marginal lake of the Sao Francisco River, MG, Brazil.
Influence of environmental heterogenity on the structure of testate amoebae (Protozoa, Rhizopoda) assemblages in the plankton of the upper Parana river floodplain, Brasil.
inflata Morphotype Cyanobacteria 4 3 3 Chlorophyta 13 4 10 Bacillariophyta 13 8 8 Euglenophyta 2 0 2 Total 32 15 23 Rotifera 12 1 12 Copepoda 5 3 4 Rhizopoda 4 2 3 Cladocera 12 8 5 Nematoda 6 4 5 Insecta 1 0 1 Total 42 18 30
Contribuição à ecologia das amebas testáceas (Protoctista, Rhizopoda) associadas à rizosfera de Eicchornia crassipes (Martius) Solomons na represa Lomba do Sabão, Porto Alegre, Rio Grande do Sul, Brasil.