Amoeba

From Free net encyclopedia

Alternate meanings: Amoeboid, Amoebozoa

For the operating system, see Amoeba distributed operating system. For the record store, see Amoeba Music.

{{Taxobox | color = khaki | name = Amoeba | image = Chaos diffluens.jpg | image_width = 240px | image_caption = Amoeba proteus | regnum = Protista | phylum = Amoebozoa | familia = Amoebidae | genus = Amoeba | genus_authority = Bery de St. Vincent 1822 }} Amoeba (also spelled ameba) is a genus of protozoa that moves by means of temporary projections called pseudopods, and is well-known as a representative unicellular organism. The word amoeba is variously used to refer to it and its close relatives, now grouped as the Amoebozoa, or to all protozoa that move using pseudopods, otherwise termed amoeboids.

Amoeba itself is found in freshwater, typically on decaying vegetation from streams, but is not especially common in nature. However, because of the ease with which they may be obtained and kept in the lab, they are common objects of study, both as representative protozoa and to demonstrate cell structure and function. The cells have several lobose pseudopods, with one large tubular pseudopod at the anterior and several secondary ones branching to the sides. The most famous species, Amoeba proteus, is 700-800 μm in length, but many others are much smaller. Each has a single nucleus, and a simple contractile vacuole which maintains its osmotic pressure, as its most recognizable features.

Early naturalists referred to Amoeba as the Proteus animalcule, after a Greek god who could change his shape. The name "amibe" was given to it by Bery St. Vincent, from the Greek amoibe, meaning change.

A good method of collecting amoeba is to lower a jar upside down until it is just above the sediment surface. Then one should slowly let the air escape so the top layer will be sucked into the jar. Deeper sediment should not be allowed to get sucked in. It is possible to slowly move the jar when tilting it to collect from a larger area. If no amoeba are found, one can try introducing some rice grains into the jar and waiting for them to start to rot. The bacteria eating the rice will be eaten by the amoeba, thus increasing the population and making them easier to find.

[edit]

Amoeba in popular culture

The North American writer Tom Robbins states, in the preface to his book Even Cowgirls Get the Blues, that amoebas are cool because they reproduce by binary fission, so the first amoeba is still alive to this day.
In the 1984 computer game Boulder Dash, Rockford, the main character, is chased all the time by a constantly-growing amoeba.
In certain places of Brazil, the term amoeba (in its Portuguese form: ameba) is used as a derogatory slang for "slow, obtuse person".