Search results
Results from the WOW.Com Content Network
Clockwise from top right: Amoeba proteus, Actinophrys sol, Acanthamoeba sp., Nuclearia thermophila., Euglypha acanthophora, neutrophil ingesting bacteria. An amoeba (/ ə ˈ m iː b ə /; less commonly spelled ameba or amœba; pl.: amoebas (less commonly, amebas) or amoebae (amebae) / ə ˈ m iː b i /), [1] often called an amoeboid, is a type of cell or unicellular organism with the ability ...
Similarly to some of the white blood cells of vertebrates, in many species amebocytes are found in the blood or body fluid (e.g. as the blood cells of Limulus, the horseshoe crab) [1] and play a role in the defense of the organism against pathogens. Depending on the species, an amebocyte may also digest and distribute food, dispose of wastes ...
Many unicellular protists, particularly protozoans, are motile and can generate movement using flagella, cilia or pseudopods. Cells which use flagella for movement are usually referred to as flagellates, cells which use cilia are usually referred to as ciliates, and cells which use pseudopods are usually referred to as amoeba or amoeboids.
[3] [4] There has been little research on mixotrophic protists, but recent studies in marine environments found mixotrophic protists contribute a significant part of the protist biomass. [5] Since protists are eukaryotes (and not prokaryotes) they possess within their cell at least one nucleus, as well as organelles such as mitochondria and ...
Some examples of organisms that exhibit this type of locomotion are amoebae (such as Amoeba proteus and Naegleria gruberi, [2]) and slime molds, as well as some cells in humans such as leukocytes. Sarcomas , or cancers arising from connective tissue cells, are particularly adept at amoeboid movement, thus leading to their high rate of metastasis .
They can also divide through budding, similarly to yeasts, or through multiple fissions, a process known as schizogony. [150] In multicellular protists, vegetative reproduction can take the form of fragmentation of body parts, or specialized propagules composed of numerous cells (e.g., in red algae). [149]
The cell's overall shape may change rapidly as pseudopodia are extended and retracted into the cell body. An Amoeba may produce many pseudopodia at once, especially when freely floating. When crawling rapidly along a surface, the cell may take a roughly monopodial form, with a single dominant pseudopod deployed in the direction of movement.
[2] [3] [4] The axopodia are microtubule-supported projections from the amoeboid cell body, and are variously used for capturing food, sensation, movement, and attachment. They are similar to Radiolaria , but they are distinguished from them by lacking central capsules and other complex skeletal elements, although some produce simple scales and ...