22-09-2017, 10:38 AM
An amoeba often called ameboid. It is a type of cell or organism that has the capacity to alter its shape, mainly by the extension and retraction of pseudopodia. The amoebas do not form a single taxonomic group; in contrast, are found in all major lineages of eukaryotic organisms. Amoeboid cells occur not only among protozoa, but also in fungi, algae, and animals. Microbiologists often use the terms "amoeboid" and "amoeba" interchangeably for any organism exhibiting amoeboid movement.
In older classification systems, most amoebas were placed in the Sarcodina class or sub-group, a group of single-celled organisms that have pseudopodia or move by protoplasmic flow. However, molecular phylogenetic studies have shown that Sarcodine is not a monophyletic group whose members share common offspring. As a result, amoeboid organisms are no longer classified together into one group.
The most well-known ameboid protists are the "giant amoeba" Carolinan Chaos and Amoeba proteus, both widely cultivated and studied in classrooms and laboratories. Other well-known species include the so-called "amoeba cerebri" Naegleria fowleri, the intestine the parasite Entamoeba histolytica, which causes amoebic dysentery, and the multicellular "social ameba" or mold of limo Dictyostelium discoideum.
In older classification systems, most amoebas were placed in the Sarcodina class or sub-group, a group of single-celled organisms that have pseudopodia or move by protoplasmic flow. However, molecular phylogenetic studies have shown that Sarcodine is not a monophyletic group whose members share common offspring. As a result, amoeboid organisms are no longer classified together into one group.
The most well-known ameboid protists are the "giant amoeba" Carolinan Chaos and Amoeba proteus, both widely cultivated and studied in classrooms and laboratories. Other well-known species include the so-called "amoeba cerebri" Naegleria fowleri, the intestine the parasite Entamoeba histolytica, which causes amoebic dysentery, and the multicellular "social ameba" or mold of limo Dictyostelium discoideum.