Arcella

testacean

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June 18, 2026

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Arcella is a genus of protozoans belonging to the order Arcellinida, commonly known as testaceans. These organisms are characterized by their single-chambered shells, or tests, which are typically found in freshwater environments, though some inhabit saltwater or moist soil. The test of Arcella is an umbrella-shaped, chitinous shell secreted by the organism itself. Arcella resembles an amoeba enclosed within this protective covering. Reproduction in Arcella occurs asexually through division or budding, and also sexually. The family Arcellidae, to which Arcella belongs, is found worldwide in soil and freshwater habitats.123

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testacean
…the inner layer (as in Arcella), sand or solid particles glued together (as in Difflugia), or siliceous plates that are secreted by cytoplasm, pushed out, and cemented in place (as in Euglypha). The genus Nebela forms its pear-shaped shell from the plates of other testaceans ingested as food. Arcella, a…
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…the inner layer (as in Arcella), sand or solid particles glued together (as in Difflugia), or siliceous plates that are secreted by cytoplasm, pushed out, and cemented in place (as in Euglypha). The genus Nebela forms its pear-shaped shell from the plates of other testaceans ingested as food. Arcella, a…
Read More