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In biology, a phylum (;
plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full version of the word or ph ...

plural
: phyla) is a level of classification or
taxonomic rank In biological classification, taxonomic rank is the relative level of a group of organisms (a taxon) in a Taxonomy (biology), taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family (biology), family, order (biology), order, ...
below
kingdom Kingdom may refer to: Monarchy * A type of monarchy * A realm ruled by: **A king, during the reign of a male monarch **A queen regnant, during the reign of a female monarch Taxonomy * Kingdom (biology), a category in biological taxonomy Arts an ...
and above
class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differently f ...
. Traditionally, in
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

botany
the term
division Division or divider may refer to: Mathematics *Division (mathematics), the inverse of multiplication *Division algorithm, a method for computing the result of mathematical division Military *Division (military), a formation typically consisting o ...
has been used instead of phylum, although the
International Code of Nomenclature for algae, fungi, and plants The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the set of rules and recommendations dealing with the formal botanical name A botanical name is a formal scientific name Science (from the Latin Latin (, ...
accepts the terms as equivalent. Depending on definitions, the animal kingdom
Animalia Animals (also called Metazoa) are multicellular Multicellular organisms are organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the L ...

Animalia
contains approximately 31 phyla; the plant kingdom
Plantae Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions ...
contains about 14, and the fungus kingdom
Fungi A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full ...

Fungi
contains about 8 phyla. Current research in
phylogenetics In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...

phylogenetics
is uncovering the relationships between phyla, which are contained in larger
clades A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual cont ...
, like
Ecdysozoa Ecdysozoa () is a group of protostome animals, including Arthropod An arthropod (, (gen. ποδός)) is an invertebrate animal having an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the ...

Ecdysozoa
and
Embryophyta The Embryophyta (), or land plants, are the most familiar group of green plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into ...
.


General description

The term phylum was coined in 1866 by
Ernst Haeckel Ernst Heinrich Philipp August Haeckel (; 16 February 1834 – 9 August 1919) was a German zoologist Zoology ()The pronunciation of zoology as is typically regarded as nonstandard, though it is not uncommon. is the branch of biology that stu ...

Ernst Haeckel
from the Greek (, "race, stock"), related to (, "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity"). ''"Wohl aber ist eine solche reale und vollkommen abgeschlossene Einheit die Summe aller Species, welche aus einer und derselben gemeinschaftlichen Stammform allmählig sich entwickelt haben, wie z. B. alle Wirbelthiere. Diese Summe nennen wir Stamm (Phylon)."'' which translates as: However, perhaps such a real and completely self-contained unity is the aggregate of all species which have gradually evolved from one and the same common original form, as, for example, all vertebrates. We name this aggregate ''Stamm'' .e., race(''Phylon''). In
plant taxonomy Plant taxonomy is the science that finds, identifies, describes, classifies, and names plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert lig ...
, August W. Eichler (1883) classified plants into five groups named divisions, a term that remains in use today for groups of plants, algae and fungi. The definitions of zoological phyla have changed from their origins in the six Linnaean classes and the four ' of
Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French naturalist Natural history is a domain of inquiry involving organism In biology, an organism () is any orga ...

Georges Cuvier
. Informally, phyla can be thought of as groupings of organisms based on general specialization of
body plan A body plan, ''Bauplan'' (German plural ''Baupläne''), or ground plan is a set of morphological features common to many members of a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ) ...
. At its most basic, a phylum can be defined in two ways: as a group of organisms with a certain degree of morphological or developmental similarity (the
phenetic In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...
definition), or a group of organisms with a certain degree of evolutionary relatedness (the
phylogenetic In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...

phylogenetic
definition). Attempting to define a level of the Linnean hierarchy without referring to (evolutionary) relatedness is unsatisfactory, but a phenetic definition is useful when addressing questions of a morphological nature—such as how successful different body plans were.


Definition based on genetic relation

The most important objective measure in the above definitions is the "certain degree" that defines how different organisms need to be members of different phyla. The minimal requirement is that all organisms in a phylum should be clearly more closely related to one another than to any other group. Even this is problematic because the requirement depends on knowledge of organisms' relationships: as more data become available, particularly from molecular studies, we are better able to determine the relationships between groups. So phyla can be merged or split if it becomes apparent that they are related to one another or not. For example, the were described as a new phylum (the Pogonophora) in the middle of the 20th century, but molecular work almost half a century later found them to be a group of
annelid The annelids (Annelida , from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the p ...
s, so the phyla were merged (the bearded worms are now an annelid
family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social territory, typically subject to the same Politic ...
). On the other hand, the highly parasitic phylum
Mesozoa The Mesozoa are minuscule, worm Worms are many different distantly related animals that typically have a long cylindrical tube-like body, no limbs, and no eyes. Worms vary in size from microscopic to over in length for marine polychaete ...
was divided into two phyla (
Orthonectida Orthonectida () is a small phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The p ...
and
Rhombozoa Dicyemida, also known as Rhombozoa, is a phylum of tiny parasite Parasitism is a symbiotic relationship between species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an ...
) when it was discovered the Orthonectida are probably
deuterostome Deuterostomia (; in Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ap ...
s and the Rhombozoa
protostome Protostomia () is the clade A clade (), also known as a monophyletic group or natural group, is a group of organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms ...
s. This changeability of phyla has led some biologists to call for the concept of a phylum to be abandoned in favour of
cladistics Cladistics (; ) is an approach to biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular ...

cladistics
, a method in which groups are placed on a "family tree" without any formal ranking of group size.


Definition based on body plan

A definition of a phylum based on body plan has been proposed by paleontologists
Graham Budd Graham Edward Budd (born 7 September 1968, Colchester Colchester () is a historic market town A market town is a European Human settlement, settlement that obtained by custom or royal charter, in the Middle Ages, the right to host marke ...
and Sören Jensen (as Haeckel had done a century earlier). The definition was posited because extinct organisms are hardest to classify: they can be offshoots that diverged from a phylum's line before the characters that define the modern phylum were all acquired. By Budd and Jensen's definition, a phylum is defined by a set of characters shared by all its living representatives. This approach brings some small problems—for instance, ancestral characters common to most members of a phylum may have been lost by some members. Also, this definition is based on an arbitrary point of time: the present. However, as it is character based, it is easy to apply to the fossil record. A greater problem is that it relies on a subjective decision about which groups of organisms should be considered as phyla. The approach is useful because it makes it easy to classify extinct organisms as "
stem group upright=1.5, Two distinct crown groups (in red) are illustrated, connected by an ancestor (black circle). The two groups form a larger crown group (lilac). In phylogenetics In biology Biology is the natural science that studies life and ...
s" to the phyla with which they bear the most resemblance, based only on the taxonomically important similarities. However, proving that a fossil belongs to the
crown group In phylogenetics In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, ph ...
of a phylum is difficult, as it must display a character unique to a sub-set of the crown group. Furthermore, organisms in the stem group of a phylum can possess the "body plan" of the phylum without all the characteristics necessary to fall within it. This weakens the idea that each of the phyla represents a distinct body plan. A classification using this definition may be strongly affected by the chance survival of rare groups, which can make a phylum much more diverse than it would be otherwise.


Known phyla


Animals

Total numbers are estimates; figures from different authors vary wildly, not least because some are based on described species, some on extrapolations to numbers of undescribed species. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million.


Plants

The kingdom Plantae is defined in various ways by different biologists (see Current definitions of Plantae). All definitions include the living
embryophyte The Embryophyta (), or land plants, are the most familiar group of green plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into ...

embryophyte
s (land plants), to which may be added the two green algae divisions,
Chlorophyta Chlorophyta or Prasinophyta is a taxon In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular inte ...
and
Charophyta The Charophyta () or charophytes () is a group of freshwater green algae, sometimes treated as a phylum, division, but also as a superdivision, or an unranked clade. The terrestrial plants, the Embryophyta, most likely emerged within Charophyta, ...
, to form the clade
Viridiplantae Viridiplantae (literally "green plants") are a clade A clade (), also known as a monophyletic group or natural group, is a group of organism In biology, an organism () is any organic, life, living system that functions as an indi ...
. The table below follows the influential (though contentious) Cavalier-Smith system in equating "Plantae" with
Archaeplastida The Archaeplastida (or kingdom ') are a major group of s, comprising the (Rhodophyta), the , and the s, and some smaller groups such as the s. All of the lineages of Archaeplastida have become ic, except for the lineage , sister to the Rhodoph ...
, a group containing Viridiplantae and the algal
Rhodophyta Red algae, or Rhodophyta ( , ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majorit ...
and
Glaucophyta The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of freshwater unicellular algae, less common today than they were during the Proterozoic. Only 15 species have been described, but more species are likely to e ...
divisions. The definition and classification of plants at the division level also varies from source to source, and has changed progressively in recent years. Thus some sources place horsetails in division Arthrophyta and ferns in division Monilophyta, while others place them both in Monilophyta, as shown below. The division Pinophyta may be used for all
gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also ...
s (i.e. including cycads, ginkgos and gnetophytes), or for conifers alone as below. Since the first publication of the
APG system The APG system (Angiosperm Phylogeny Group system) of plant classification is the first version of a modern, mostly molecular A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. ...
in 1998, which proposed a classification of angiosperms up to the level of
order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or waste, and the habit of achieving a ...
s, many sources have preferred to treat ranks higher than orders as informal clades. Where formal ranks have been provided, the traditional divisions listed below have been reduced to a very much lower level, e.g. subclasses.


Fungi

Phylum Microsporidia is generally included in kingdom Fungi, though its exact relations remain uncertain, and it is considered a
protozoa Protozoa (singular protozoon or protozoan, plural protozoa or protozoans) is an informal term for a group of Unicellular organism, single-celled eukaryotes, either free-living or Parasitism, parasitic, that feed on organic matter such as other mi ...

protozoa
n by the International Society of Protistologists (see
Protista A protist () is any eukaryotic organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It is a synonym f ...
, below). Molecular analysis of Zygomycota has found it to be
polyphyletic 300px, Cladogram of the primates, showing a monophyly (the simians, in yellow), a paraphyly">monophyly.html" ;"title="primates, showing a monophyly">primates, showing a monophyly (the simians, in yellow), a paraphyly (the prosimians, in cyan, inc ...

polyphyletic
(its members do not share an immediate ancestor), which is considered undesirable by many biologists. Accordingly, there is a proposal to abolish the Zygomycota phylum. Its members would be divided between phylum Glomeromycota and four new subphyla ''
incertae sedis ' () or ''problematica'' is a term used for a taxonomic Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific ...
'' (of uncertain placement): Entomophthoromycotina,
Kickxellomycotina Kickxellomycotina is a fungus grouping. The name was changed from "Harpellomycotina", because "Kickxellomycotina" had an older stem. It came from the genus ''Kickxella'', named after Jean Kickx. Orders include Asellariales, Kickxellales, Dimarga ...
,
Mucoromycotina Mucoromycotina is a subphylum of uncertain placement in Fungi. It was considered part of the phylum Zygomycota Zygomycota, or zygote fungi, is a former division or phylum of the kingdom Fungi. The members are now part of two phyla the Muco ...
, and
Zoopagomycotina The Zoopagomycotina are a subdivision (''incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigma ...
.


Protista

Kingdom
Protista A protist () is any eukaryotic organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It is a synonym f ...
(or Protoctista) is included in the traditional five- or six-kingdom model, where it can be defined as containing all
eukaryote Eukaryotes () are organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interact ...

eukaryote
s that are not plants, animals, or fungi. Protista is a
polyphyletic 300px, Cladogram of the primates, showing a monophyly (the simians, in yellow), a paraphyly">monophyly.html" ;"title="primates, showing a monophyly">primates, showing a monophyly (the simians, in yellow), a paraphyly (the prosimians, in cyan, inc ...

polyphyletic
taxon, which is less acceptable to present-day biologists than in the past. Proposals have been made to divide it among several new kingdoms, such as
Protozoa Protozoa (singular protozoon or protozoan, plural protozoa or protozoans) is an informal term for a group of Unicellular organism, single-celled eukaryotes, either free-living or Parasitism, parasitic, that feed on organic matter such as other mi ...

Protozoa
and
Chromista Chromista is a biological kingdom consisting of single-celled and multicellular eukaryotic Eukaryotes () are organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual conti ...
in the Cavalier-Smith system. Protist taxonomy has long been unstable, with different approaches and definitions resulting in many competing classification schemes. The phyla listed here are used for Chromista and Protozoa by the
Catalogue of Life The Catalogue of Life is an online databaseAn online database is a database A database is an organized collection of data Data are units of information Information can be thought of as the resolution of uncertainty; it answers the q ...
, adapted from the system used by the International Society of Protistologists. The Catalogue of Life includes
Rhodophyta Red algae, or Rhodophyta ( , ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majorit ...
and
Glaucophyta The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of freshwater unicellular algae, less common today than they were during the Proterozoic. Only 15 species have been described, but more species are likely to e ...
in kingdom Plantae, but other systems consider these phyla part of Protista.


Bacteria

Currently there are 29 phyla accepted by
List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature ('LPSN'') is an online database that maintains information on the naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of Nomenclat ...
(LPSN) #
Acidobacteria Acidobacteria is a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of ...
, phenotypically diverse and mostly uncultured #
Actinobacteria The Actinobacteria are a phylum of mostly Gram-positive bacteria File:Gram stain 01.jpg, 300px, Violet-stained gram-positive cocci and pink-stained gram-negative bacillus (shape), bacilli In bacteriology, gram-positive bacteria are bacteria tha ...
, High-G+C Gram positive species #
Aquificae The Aquificae phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a nou ...
, only 14 thermophilic genera, deep branching #
Armatimonadetes Armatimonadetes is a phylum of gram-negative bacteria. History Armatimonadetes was originally described solely on the basis of environmental 16S ribosomal RNA, 16S rRNA gene clone sequences, and was temporarily titled candidate phylum OP10. How ...
#
Bacteroidetes The phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typicall ...
#
Caldiserica ''Caldisericum exile'' is a species of bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically ...
, formerly candidate division OP5, ''Caldisericum exile'' is the sole representative #
Chlamydiae The Chlamydiae are a bacterial Phylum (biology), phylum and Class (biology), class whose members are remarkably diverse, including pathogens of humans and animals, symbiosis, symbionts of ubiquitous protozoa, and marine sediment forms not yet wel ...
, only 6 genera #
Chlorobi The green sulfur bacteria (Chlorobiaceae) are a family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of ...

Chlorobi
, only 7 genera, green sulphur bacteria # Chloroflexi, green non-sulphur bacteria # Chrysiogenetes, only 3 genera (''Chrysiogenes arsenatis'', ''Desulfurispira natronophila'', ''Desulfurispirillum alkaliphilum'') #
Cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical ...

Cyanobacteria
, also known as the blue-green algae #
Deferribacteres The Deferribacteraceae are a family of gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram stain, gram-staining method of bacterial differentiation. They are characterized by th ...
# Deinococcus-Thermus, ''Deinococcus radiodurans'' and ''Thermus aquaticus'' are "commonly known" species of this phyla # Dictyoglomi #
Elusimicrobia The phylum Elusimicrobia, previously known as "Termite Group 1", has been shown to be widespread in different ecosystems like marine environment, sewage sludge, contaminated sites and soils, and toxic wastes. The high abundance of 'Elusimicrobia' ...
, formerly candidate division Thermite Group 1 #
Fibrobacteres Fibrobacteres is a small bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micromet ...

Fibrobacteres
#
Firmicutes The Firmicutes (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman ...
, Low-G+C Gram positive species, such as the spore-formers
Bacilli Bacilli is a taxonomic Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification scheme. Originally ...
(aerobic) and
Clostridia The Clostridia are a highly polyphyletic class of Firmicutes The Firmicutes (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the ar ...
(anaerobic) #
Fusobacteria Fusobacteria are obligately anaerobic non-sporeforming Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram stain, gram-staining method of bacterial differentiation. They are characteriz ...
#
Gemmatimonadetes The Gemmatimonadetes (alternatively Gemmatimonadota) are a phylum of bacterium, bacteria established in 2003. The phylum contains two classes Gemmatimonadetes and Longimicrobia. Species The type species ''Gemmatimonas aurantiaca'' strain T-27T wa ...
#
Lentisphaerae Lentisphaerae is a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of ...
, formerly clade VadinBE97 #
Nitrospira ''Nitrospira'' (from Latin: nitro, meaning "nitrate" and Greek: spira, meaning "spiral") translate into “a nitrate spiral” is a genus of bacteria within the monophyletic clade of Nitrospirae Nitrospirae is a phylum of bacteria. It contains ...
#
Planctomycetes The Planctomycetes are a phylum of widely distributed bacteria, occurring in both water, aquatic and terrestrial habitats. They play a considerable role in global carbon and nitrogen cycles, with many species of this phylum capable of anaerobic amm ...
#
Proteobacteria Proteobacteria is a major phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plu ...
, the most known phyla, containing species such as ''
Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative bacteria, Gram-negative, Facultative anaerobic organism, facultative anaer ...

Escherichia coli
'' or ''
Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram stain, gram-staining method of bacterial differentiation. They are characterized ...
'' #
Spirochaetes A spirochaete () or spirochete is a member of the phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical ...
, species include ''
Borrelia burgdorferi ''Borrelia burgdorferi'' is a bacterial Bacteria (; common noun bacteria, singular bacterium) are a type of biological cell. They constitute a large domain of prokaryotic microorganism A microorganism, or microbe,, ''mikros'', " ...
'', which causes Lyme disease # #
Tenericutes Tenericutes (tener cutis: soft skin) is a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of ...
, alternatively class
Mollicutes Mollicutes is a class of bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micromet ...
in phylum
Firmicutes The Firmicutes (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman ...
(notable genus: ''
Mycoplasma ''Mycoplasma'' (plural mycoplasmas or mycoplasmata) is a genus of bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokary ...
'') # #
Thermotogae The Thermotogae are a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural ...
, deep branching #
Verrucomicrobia Verrucomicrobia is a phylum of Gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram stain, gram-staining method of bacterial differentiation. They are characterized by their cell ...


Archaea

Currently there are five phyla accepted by
List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature ('LPSN'') is an online database that maintains information on the naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of Nomenclat ...
(LPSN). #
Crenarchaeota The Crenarchaeota (also known as Crenarchaea or eocytes) are archaea that have been classified as a phylum (biology), phylum of the Archaea domain. Initially, the Crenarchaeota were thought to be sulfur-dependent extremophiles but recent studies ...
, second most common archaeal phylum #
Euryarchaeota Euryarchaeota (Greek for "broad old quality") is a phylum (biology), phylum of archaea. It is one of two phyla of archaea, the other being crenarchaeota. Euryarchaeota are highly diverse and include methanogens, which produce methane and are ofte ...
, most common archaeal phylum #
Korarchaeota In alpha taxonomy, taxonomy, the Korarchaeota are a phylum (biology), phylum of the Archaea. The name is derived from the Greek noun koros or kore, meaning ''young man'' or ''young woman,'' and the Greek adjective archaios which means ''ancient.' ...

Korarchaeota
#
Nanoarchaeota Nanoarchaeota (Greek, "dwarf or tiny ancient one") are a phylum (biology), phylum of the Archaea.See the National Center for Biotechnology Information, NCBI]webpage on Nanoarchaeota Data extracted from the This phylum currently has only one repr ...
, ultra-small symbiotes, single known species #
Thaumarchaeota The Thaumarchaeota or Thaumarchaea (from the grc, θαῦμα, thaûma, miracle) are a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of ...


See also

*
Cladistics Cladistics (; ) is an approach to biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular ...

Cladistics
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Phylogenetics In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...

Phylogenetics
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Systematics Biological Biology is the natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), o ...
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Taxonomy Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification scheme. Originally used only about biological ...


Notes


References


External links


Are phyla "real"? Is there really a well-defined "number of animal phyla" extant and in the fossil record?


{{Authority control Plant divisions,