phylum


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phylum,

in taxonomy: see classificationclassification,
in biology, the systematic categorization of organisms into a coherent scheme. The original purpose of biological classification, or systematics, was to organize the vast number of known plants and animals into categories that could be named, remembered, and
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Phylum

 

(also type), the highest taxonomic category in the classification of animals. A phylum, or type, is made up of related classes. The term “type” was proposed in 1825 by H. de Blain-ville, who applied it to the four “branches” of animals distinguished by G. Cuvier in 1812.

Phyla vary in size: for example, the phylum Porifera comprises approximately 5,000 species, whereas the phylum Pogonophora has only about 100 species. Phyla are frequently divided into sub-phyla. For example, the phylum Chordata has four sub-phyla—Cephalochordata, Tunicata, Acrania, and Vertebrata. Organisms belonging to the same phylum are marked by the same structural organization. The number of phyla and their size vary from one classification system to another. Some taxonomists recognize as few as ten phyla, and others as many as 33. However, these differences do not diminish the importance of phyla as categories that reflect the principal branches of the phylogenetic tree of the animal kingdom.

In plant classification, which has been worked out independently from animal classification, the taxonomic category corresponding to a phylum is called a division.

M. E. KIRPICHNIKOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

phylum

[′fī·ləm]
(systematics)
A major taxonomic category in classifying animals (and plants in some systems), composed of groups of related classes.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

phylum

a major taxonomic division of living organisms that contain one or more classes. An example is the phylum Arthropoda (insects, crustaceans, arachnids, etc., and myriapods)
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
That said, sampling processing procedures can affect this ratio because the phylum Firmicutes consists of mostly gram-positive bacteria with thick cell walls that can make them difficult to lyse, thus high-energy lysis steps (e.g., bead-beating) are important in extraction protocols.
However, this study did not observe differences in the Firmicutes phylum.
The Chloroflexi was the third largest phylum in the rhizosphere library of Fareed-06 (Table 2) accounted for 17% of total clones but least dominant in the rhizosphere of chakwal-50 (Table 3) with sharing of 4% of total clones primarily represented by one common class Anaerolinae in both rhizospheric soils.
For example, a phylum must be as old as the oldest class it contains.
The numerical abundance of Acidobacteria in soil may reflect this phylum's contribution to decomposition, an important ecological function suggested for Acidobacteria.
Bacteroidetes was the second abundant phylum in the present dataset, including 2244 sequences (nearly 17.8% of all bacterial sequences), which were assigned to 109 known genera, with 868 OTUs and a Simpson diversity index of 0.0007 (Figure 4).
The C value data were compared with those of the phylum Bryozoa, which is related closely to the phylum Brachiopoda.
The results, published online in the Journal of Environmental Quality, showed that certain types of bacteria, in the phylum Bacteroidetes, were more predominant in the fine dust while other types, in the phylum Proteobacteria, were more predominant in the coarse sediments.
This multistation laboratory uses a combination of preserved and live specimens, slides, and images to present samples of each phylum. The exercise is designed to take advantage of an aquarium in the classroom but does not require one.
Also known as blue-green algae, blue-green bacteria, and cyanophyta, bacteria in the phylum obtain energy through photosynthesis and are the only group of organisms that can reduce nitrogen and carbon in aerobic conditions.
Implementations may include providing a raw cellulose stream by mixing a waste cellulose feed and an algae cellulose feed and hydrolyzing the raw cellulose stream to form a hydrolyzed cellulose stream by reacting the raw cellulose stream with one or more fungi from the phylum Neocallimastigomycota.