AskDefine | Define phylum

Dictionary Definition

phylum

Noun

1 (linguistics) a large group of languages that are historically related
2 (biology) the major taxonomic group of animals and plants; contains classes [also: phyla (pl)]

User Contributed Dictionary

English

Etymology

From etyl grc φῦλον.

Noun

  1. In the context of "biology|taxonomy": A rank in the classification of organisms, below kingdom and above class; also called a division, especially in describing plants; a taxon at that rank
    Mammals belong to the phylum Chordata.

Translations

(biology, taxonomy) A rank in the classification of organisms, below kingdom and above class

Extensive Definition

In biological taxonomy, a 'phylum' plural: phyla) is a taxonomic rank at the level below Kingdom and above Class. "Phylum" is adopted from the Greek phylai, the clan-based voting groups in Greek city-states. Phyla represent the largest generally accepted groupings of animals and other living things with certain evolutionary traits, although the phyla themselves may sometimes be grouped into superphyla (e.g. Ecdysozoa with eight phyla, including arthropods and roundworms; and Deuterostomia with the echinoderms, chordates, hemichordates and xenoturbellae). Informally, phyla can be thought of as grouping animals based on general body plan; this is morphological grouping. Thus despite the seemingly different external appearances of organisms, they are classified into phyla based on their internal organizations. For example, though seemingly divergent, spiders and crabs both belong to Arthropoda, whereas earthworms and tapeworms, similar in shape, are from Annelida and Platyhelminthes, respectively. Although the International Code of Botanical Nomenclature allows the use of the term "Phylum" in reference to plants, the term "Division" is almost always used by botanists.
The best known animal phyla are the Mollusca, Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Arthropoda, Echinodermata, and Chordata, the phylum to which humans belong. Although there are approximately 35 phyla, these nine include the majority of the species. Many phyla are exclusively marine, and only one phylum is entirely absent from the world's oceans: the Onychophora or velvet worms. The most recently discovered phylum is Cycliophora found in 1993; only three phyla were discovered in the last century.
The Cambrian explosion was a great flowering of life forms that occurred between roughly 530 and 520 million years ago; during this time organisms similar to, but not strictly members of, modern phyla existed; whilst some appear to be represented in the Ediacaran biota, it remains a matter of debate whether all phyla existed prior to the explosion. Over time the roles among different phyla have varied. For instance, during the Cambrian, the dominant megafauna, or large animals, were arthropods, whereas now the megafauna is dominated by vertebrates (chordata). The arthropods are still by far the most dominant phylum.

List of animal phyla

Groups formerly ranked as phyla

List of plant divisions

List of fungi divisions

See also

References

Etymology:
phylum in Old English (ca. 450-1100): Stefn (līfcræft)
phylum in Aragonese: Filo (biolochía)
phylum in Breton: Skourrad
phylum in Catalan: Fílum
phylum in Czech: Kmen (biologie)
phylum in Welsh: Ffylwm
phylum in Danish: Række (biologi)
phylum in German: Stamm (Biologie)
phylum in Estonian: Hõimkond
phylum in Spanish: Filo
phylum in Esperanto: Filumo
phylum in French: Embranchement (biologie)
phylum in Irish: Fíleam
phylum in Korean: 문 (생물학)
phylum in Croatian: Koljeno (taksonomija)
phylum in Indonesian: Filum
phylum in Icelandic: Fylking (flokkunarfræði)
phylum in Italian: Phylum
phylum in Hebrew: מערכה (טקסונומיה)
phylum in Latin: Phylum
phylum in Lithuanian: Tipas
phylum in Latvian: Tips (bioloģija)
phylum in Hungarian: Törzs (rendszertan)
phylum in Malay (macrolanguage): Filum
phylum in Dutch: Stam (biologie)
phylum in Japanese: 門 (分類学)
phylum in Norwegian: Rekke (biologi)
phylum in Occitan (post 1500): Embrancament (biologia)
phylum in Polish: Typ (biologia)
phylum in Portuguese: Filo
phylum in Quechua: Rikch'aq putu
phylum in Russian: Тип (биология)
phylum in Sicilian: Filu (bioluggìa)
phylum in Simple English: Phylum
phylum in Slovenian: Deblo (biologija)
phylum in Finnish: Pääjakso (biologia)
phylum in Swedish: Stam (biologi)
phylum in Thai: ไฟลัม
phylum in Turkish: Şube (biyoloji)
phylum in Vietnamese: Ngành (sinh học)
phylum in Chinese: 門 (生物)

Synonyms, Antonyms and Related Words

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