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The contractile vacuole is predominant in species that do not have a cell wall, but there are exceptions (notably Chlamydomonas) which do possess a cell wall. Through evolution , the contractile vacuole has typically been lost in multicellular organisms, but it still exists in the unicellular stage of several multicellular fungi , as well as in ...
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes (salts in solution which in this case is represented by body fluid) to keep the body fluids from becoming too diluted or concentrated.
Paramecium (/ ˌ p ær ə ˈ m iː s (i) ə m / PARR-ə-MEE-s(ee-)əm, /-s i ə m /-see-əm, plural "paramecia" only when used as a vernacular name) [2] is a genus of eukaryotic, unicellular ciliates, widespread in freshwater, brackish, and marine environments. Paramecia are often abundant in stagnant basins and ponds.
Most ciliates also have one or more prominent contractile vacuoles, which collect water and expel it from the cell to maintain osmotic pressure, or in some function to maintain ionic balance. In some genera, such as Paramecium , these have a distinctive star shape, with each point being a collecting tube.
Paramecium aurelia [1] are unicellular organisms belonging to the genus Paramecium of the phylum Ciliophora. [2] They are covered in cilia which help in movement and feeding. [ 2 ] Paramecium can reproduce sexually , asexually , or by the process of endomixis . [ 3 ]
Paramecium bursaria click to see cilia: Foraminiferans, and some marine amoebae, ciliates and flagellates. Amoebas (amoeboids) Pseudopods (Greek for false feet) are lobe-like appendages which amoebas use to anchor to a solid surface and pull themselves forward. They can change their shape by extending and retracting these pseudopods. [43] Amoeba
The paramecium does this by reversing the direction in which its cilia beat. This results in stopping, spinning or turning, after which point the paramecium resumes swimming forward. If multiple avoidance reactions follow one another, it is possible for a paramecium to swim backward, though not as smoothly as swimming forward. [1]
Osmolytes are low-molecular-weight organic compounds that influence the properties of biological fluids. Osmolytes are a class of organic molecules that play a significant role in regulating osmotic pressure and maintaining cellular homeostasis in various organisms, particularly in response to environmental stressors. [1]