Sarcodina


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Related to Sarcodina: Ciliophora, Sporozoa, Zoomastigina

Sarcodina,

the largest phylum (11,500 living species and 33,000 fossil species) of protozoansprotozoan
, informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms that live as single cells or in simple colonies and that show no differentiation into tissues.
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). It comprises the amebasameba
or amoeba
, common name for certain one-celled organisms belonging to the phylum Sarcodina of the kingdom Protista. Amebas were previously classified as members of the animal kingdom.
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 and related organisms; which are all solitary cells that move and capture food by means of pseudopods, flowing temporary extensions of the cell. Most sarcodines are free living; others are parasitic. One of these parasites is the causative organism of amebic dysenterydysentery
, inflammation of the intestine characterized by the frequent passage of feces, usually with blood and mucus. The two most common causes of dysentery are infection with a bacillus (see bacteria) of the Shigella group, and infestation by an ameba,
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. With the exception of chloroplasts, sarcodines are identical to the ameboid members of the phylum ChrysophytaChrysophyta
, phylum (division) of unicellular marine or freshwater organisms of the kingdom Protista consisting of the diatoms (class Bacillariophyceae), the golden, or golden-brown, algae (class Chrysophyceae), and the yellow-green algae (class Xanthophyceae).
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. Sarcodines may reproduce asexually by cell division, often without breakdown of the nuclear envelope that is typical in mitosis, or sexually by meiosis and the production of haploid gametes, followed by fusion of gametes and the formation of zygotes.

The sarcodines include the naked forms (amebas) and forms with perforated shells, or tests, through which pseudopods may be extended. Best known of the shelled forms are the foraminiferansforaminiferan
, common name for members of the class Foraminifera, large, shelled ameboid protozoans belonging to the phylum Sarcodina. Most foraminiferan shells are calcareous, but some are siliceous, and others are built of sand grains.
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, with calcium carbonate shells.

Sarcodina

 

a class of invertebrates of the phylum Protozoa. The pseudopods of Sarcodina serve as the organelles of locomotion and food procurement. The majority of Sarcodina are free-living forms. There are three subclasses—Rhizopoda, Radiolaria, and Heliozoa. Rhizopoda include the orders Amoebina, Testacea, and Foraminifera; some zoologists call all Sarcodina rhizopods. Radiolaria and Heliozoa are sometimes regarded as being orders, in which case the Sarcodina are divided into five orders.

Sarcodina

[‚sär·kə′dī·nə]
(invertebrate zoology)
A superclass of Protozoa in the subphylum Sarcomastigophora in which movement involves protoplasmic flow, often with recognizable pseudopodia.
References in periodicals archive ?
Observations on Centroheliozoa of the Volga basin (Protozoa: Sarcodina).
Marine and brackish-water centrohelids (Centroheliozoa, Sarcodina) of Kandalaksha Bay of the White Sea.