Testate amoebae

Shell of Cylindrifflugia acuminata: an agglutinated test made up of mineral particles glued together with secretions from within the cell

Testate amoebae (formerly thecamoebians, Testacea or Thecamoeba) are a polyphyletic group of unicellular amoeboid protists, which differ from naked amoebae in the presence of a test that partially encloses the cell, with an aperture from which the pseudopodia emerge, that provides the amoeba with shelter from predators and environmental conditions.

The test of some species is produced entirely by the amoeba and may be organic, siliceous or calcareous depending on the species (autogenic tests), whereas in other cases the test is made up of particles of sediment collected by the amoeba which are then agglutinated together by secretions from within the cell (xenogenic tests). A few taxa (Hyalospheniidae) can build either type, depending on the circumstances and availability of foreign material.[1]

The assemblage referred to as "testate amoebae" is actually composed of several, unrelated groups of organisms. However, some features they all share that have been used to group them together include the presence of a test (regardless of its composition) and pseudopodia that do not anastomose.[2]

Testate amoebae can be found in most freshwater environments, including lakes, rivers, cenotes,[3] as well as mires and soils.

The strong and resistant nature of the tests allows them to be preserved long after the amoeba has died. These characteristics, along with the sensitivity that some species display to changes in environmental conditions (such as temperature, pH, and conductivity), has sparked their use as bioindicators and paleoclimate proxies in recent years.[4]

  1. ^ B., Scott, D. (2001). Monitoring in coastal environments using Foraminifera and Thecamoebian indicators. Medioli, F. S., Schafer, Charles T. Cambridge: Cambridge University Press. ISBN 978-0521561730. OCLC 70724931.{{cite book}}: CS1 maint: multiple names: authors list (link)
  2. ^ Kosakyan, Anush; Gomaa, Fatma; Lara, Enrique; Lahr, Daniel J.G. (2016). "Current and future perspectives on the systematics, taxonomy and nomenclature of testate amoebae". European Journal of Protistology. 55 (Pt B): 105–117. doi:10.1016/j.ejop.2016.02.001. hdl:11380/1302106. PMID 27004416.
  3. ^ Sigala, Itzel; Lozano-García, Socorro; Escobar, Jaime; Pérez, Liseth; Gallegos-Neyra, Elvia (2016-06-28). "Testate Amoebae (Amebozoa: Arcellinida) in Tropical Lakes of Central Mexico". Revista de Biología Tropical. 64 (1): 377–397. doi:10.15517/rbt.v64i1.18004. ISSN 2215-2075. PMID 28862826.
  4. ^ Mitchell, Edward A. D.; Charman, Daniel J.; Warner, Barry G. (2008-08-01). "Testate amoebae analysis in ecological and paleoecological studies of wetlands: past, present and future" (PDF). Biodiversity and Conservation. 17 (9): 2115–2137. doi:10.1007/s10531-007-9221-3. ISSN 0960-3115. S2CID 27912982.