• species
  • Most of the free-living freshwater amoebae commonly found in pond water, ditches and lakes are microscopic, but some species, such as the so-called "giant amoebae" Pelomyxa palustris and Chaos carolinense, can be large enough to see with the naked eye. (wikipedia.org)
  • Although there are freshwater species, the great majority are marine (salt water) species, ranging from tidal zones to depths exceeding 8,800 m (5.5 mi). (wikipedia.org)
  • A few species of sponge that live in food-poor environments have become carnivores that prey mainly on small crustaceans. (wikipedia.org)
  • When conditions deteriorate, for example as temperatures drop, many freshwater species and a few marine ones produce gemmules, "survival pods" of unspecialized cells that remain dormant until conditions improve and then either form completely new sponges or recolonize the skeletons of their parents. (wikipedia.org)
  • Demosponges constitute about 90% of all known sponge species, including all freshwater ones, and have the widest range of habitats. (wikipedia.org)
  • The largest and best known species, the so-called "giant amoeba" Chaos carolinense, can reach lengths of 5 mm, although most specimens fall between 1 and 3 mm. (wikipedia.org)
  • Recently, molecular phylogenetic studies of this species have confirmed the view of some earlier researchers that it is more closely related to Amoeba than to Pelomyxa. (wikipedia.org)
  • Free-living species are common in both salt and freshwater, as well as soil, moss and leaf litter. (wikipedia.org)
  • citation needed] When food is scarce, most species can form cysts, which may be carried aerially and introduce them to new environments. (wikipedia.org)
  • Pelomyxa
  • However, studies of the fine structure and physiology of the amoeba made it increasingly clear that there were profound differences between it and the other Pelomyxa (including the complete absence, in true Pelomyxa, of mitochondria). (wikipedia.org)
  • Multinucleate amoebae like Chaos and Pelomyxa (the so-called "giant amoebae") may be several millimetres in length, and some multicellular amoebozoa, such as the "dog vomit" slime mold Fuligo septica, can cover an area of several square meters. (wikipedia.org)
  • cytoplasm
  • This process regulates the amount of water present in the cytoplasm of the amoeba. (wikipedia.org)
  • The vesicle containing the ingested particle, the phagosome, then fuses with a lysosome containing hydrolytic enzymes to produce a phagolysosome, which breaks down the food particle into small molecules that diffuse into the cytoplasm for use in cellular metabolism. (lumenlearning.com)
  • testate
  • Free-living amoebae may be "testate" (enclosed within a hard shell), or "naked" (a.k.a. gymnamoebae, lacking any hard covering). (wikipedia.org)
  • The shells of testate amoebae may be composed of various substances, including calcium, silica, chitin, or agglutinations of found materials like small grains of sand and the frustules of diatoms. (wikipedia.org)
  • microorganisms
  • In 1848, in light of advancements in cell theory pioneered by Theodor Schwann and Matthias Schleiden, the anatomist and zoologist C.T. von Siebold proposed that the bodies of microorganisms such as ciliates and amoebae were made up of single cells, similar to those from which the multicellular tissues of plants and animals were constructed. (wikipedia.org)
  • cell
  • The stages of phagocytosis include the engulfment of a food particle, the digestion of the particle using enzymes contained within a lysosome, and the expulsion of undigested materials from the cell. (lumenlearning.com)
  • Phagocytosis is involved in the acquisition of nutrients for some cells, and in the immune system it is a major mechanism used to remove pathogens and cell debris. (blogspot.com)
  • In ciliates there is a specialized groove or chamber in the cell where phagocytosis takes place, called the cytostome or mouth. (blogspot.com)
  • known
  • Sexual phenomena have not been observed in Amoeba, although sexual exchange of genetic material is known to occur in other Amoebozoan groups. (wikipedia.org)
  • bodies
  • Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. (wikipedia.org)