Amoeboid Totally Explained

Everything about Amoeboid totally explained

Amoeboids are unicellular lifeforms that mainly consist of contractile vacuoles, a nucleus, and cytoplasm as their basic structure. They move and feed by means of temporary cytoplasmic projections, called pseudopods (false feet). They have appeared in a number of different groups. Some cells in multicellular animals may be amoeboid, for instance human white blood cells, which consume pathogens. Many protists also exist as individual amoeboid cells, or take such a form at some point in their life-cycle. The most famous such organism is Amoeba proteus; the name amoeba is variously used to describe its close relatives, other organisms similar to it, or the amoeboids in general.

Morphological categories

Amoeboids may be divided into several morphological categories based on the form and structure of the pseudopods. Those where the pseudopods are supported by regular arrays of microtubules are called actinopods, and forms where they're not are called rhizopods, further divided into lobose, filose, and reticulose amoebae. There is also a strange group of giant marine amoeboids, the xenophyophores, that don't fall into any of these categories.

Lobose pseudopods ť Lobose pseudopods are blunt, and there may be one or several on a cell, which is usually divided into a layer of clear ectoplasm surrounding more granular endoplasm. Most, including Amoeba itself, move by the body mass flowing into an anterior pseudopod. The vast majority form a monophyletic group called the Amoebozoa, which also includes most slime molds. A second group, the Percolozoa, includes protists that can transform between amoeboid and flagellate forms.

Filose pseudopods ť Filose pseudopods are narrow and tapering. The vast majority of filose amoebae, including all those that produce shells, are placed within the Cercozoa together with various flagellates that tend to have amoeboid forms. The naked filose amoebae comprise two other groups, the vampyrellids and nucleariids. The latter appear to be close relatives of animals and fungi.

Reticulose pseudopods ť Reticulose pseudopods are cytoplasmic strands that branch and merge to form a net. They are found most notably among the Foraminifera, a large group of marine protists that generally produce multi-chambered shells. There are only a few sorts of naked reticulose amoeboids, notably the gymnophryids, and their relationships are not certain.

Actinopods ť Actinopods are divided into the radiolaria and heliozoa. The radiolaria are mostly marine protists with complex internal skeletons, including central capsules that divide the cells into granular endoplasm and frothy ectoplasm that keeps them buoyant. The heliozoa include both freshwater and marine forms that use their axopods to capture small prey, and only have simple scales or spines for skeletal elements. Both groups appear to be polyphyletic.

However, amoeboids have appeared separately in many other groups, including various different lines of algae not listed above.

Subphylum Sarcodina ť Sarcodina is a subphylum of the phylum Sarcomastigophora, of unicellular life forms that move by cytoplasmic flow. Some species use cytoplasmic extensions called pseudopodia for locomotion or feeding. The subphylum includes such protozoa as the common amoeba and the Foraminifera and Radiolaria. Most members of the subphylum reproduce asexually through fission, although some reproduce sexually. Sarcodina is sometimes subdivided into two classes - Rhizopoda and Actinopoda.

Further Information

Get more info on 'Amoeboid'.

External Link Exchanges

Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:

<a href="http://amoeboid.totallyexplained.com">Amoeboid Totally Explained</a>

Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned.