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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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(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.



A major taxonomic category in classifying animals (and plants in some systems), composed of groups of related classes.


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)
References in periodicals archive ?
Influence of acarbose addition on the changes in the composition of ruminal bacterial microbiota at the phylum level Proportion of the total Phylum bacterial population (%) SEM p value Control Acarbose Firmicutes 57.
C) Proteobacteria content in vehicle-treated control and PCB-treated sedentary and exercised mice; values are mean [+ or -] SE of pooled taxa in phylum Proteobacteria.
They are also in separate classes within the phylum.
On graph paper, create a bar graph comparing the number of organisms from each phylum that were found in the ship ballast.
Since echinoderms share deuterstome ancestry with the Phylum Chordata, it is of particular interest to examine the recently decoded genome of the sea urchin (Sea Urchin Genome Sequencing Consortium 2006).
The [chi square] contingency tables were used to evaluate the possible differences in the prey items clustered by phylum (Arthropoda, Chordata, and Mollusca) among locations.
Animals soon had to fit into certain categories: Kingdom, Phylum, Class, Order, Family, Genus, Species.
This fall, the most recognizable phylum is the journalistic compilation.
Key Words: Gordius difficilis, Gordius robustus, Phylum Nematomorpha, Lepomis megalotis, Salmo trutta, Centrarchidae, Salmonidae, Minnesota, Missouri
The Ecology of Freshwater Molluscs adds a more global perspective on a phylum that is diverse and very numerous, second only to the Arthropoda in number of species.
Asterisks indicate only one class identified in that phylum and dashes indicate that no species were found.
The pikachu is one species of Pokemon, of the electric phylum, for example.