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Phylum facts for kids

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Biological classification L Pengo vflip Life Domain Kingdom Phylum Class Order Family Genus Species
The hierarchy of biological classification's eight major taxonomic ranks. A kingdom contains one or more phyla. Intermediate minor rankings are not shown.

In biology, a phylum (/ˈfləm/; pl.: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering the relationships among phyla within larger clades like Ecdysozoa and Embryophyta.

General description

The term phylum was coined in 1866 by Ernst Haeckel from the Greek phylon (φῦλον, "race, stock"), related to phyle (φυλή, "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"): "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 [a] Stamm [i.e., stock] (Phylon)." In plant taxonomy, 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 embranchements of Georges Cuvier.

Informally, phyla can be thought of as groupings of organisms based on general specialization of body plan. 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 definition), or a group of organisms with a certain degree of evolutionary relatedness (the 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 bearded worms 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 annelids, so the phyla were merged (the bearded worms are now an annelid family). On the other hand, the highly parasitic phylum Mesozoa was divided into two phyla (Orthonectida and Rhombozoa) when it was discovered the Orthonectida are probably deuterostomes and the Rhombozoa protostomes.

This changeability of phyla has led some biologists to call for the concept of a phylum to be abandoned in favour of placing taxa in clades 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 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 groups" 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 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


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.

Protostome Bilateria Nephrozoa
Basal/disputed Non-Bilateria
Phylum Meaning Common name Distinguishing characteristic Taxa described
Acanthocephala Thorn head Acanthocephalans, thorny-headed worms, spiny-headed worms Worm with a proboscis armed with hooks 1420
Annelida Little ring Segmented worms Multiple circular segments &&&&&&&&&&022000.&&&&&022,000+ extant
Agmata Fragmented Agmates Calcareous conical shells 5 species, extinct
Archaeocyatha Ancient cups Archaeocyathids An extinct taxon of sponge-grade, reef-building organisms living in warm tropical and subtropical waters during the Early Cambrian. 3 known classes (Extinct)
Arthropoda Jointed foot Arthropods Segmented bodies and jointed limbs, with Chitin exoskeleton &&&&&&&&01250000.&&&&&01,250,000+ extant; 20,000+ extinct
Brachiopoda Arm foot Lampshells Lophophore and pedicle &&&&&&&&&&&&0300.&&&&&0300–500 extant; 12,000+ extinct
Bryozoa (Ectoprocta) Moss animals Moss animals, sea mats, ectoprocts Lophophore, no pedicle, ciliated tentacles &&&&&&&&&&&06000.&&&&&06,000 extant
Chaetognatha Longhair jaw Arrow worms Chitinous spines either side of head, fins &&&&&&&&&&&&0100.&&&&&0100 extant
Chordata With a cord Chordates Hollow dorsal nerve cord, notochord, pharyngeal slits, endostyle, post-anal tail &&&&&&&&&&055000.&&&&&055,000+
Cnidaria Stinging nettle Cnidarians Nematocysts (stinging cells) &&&&&&&&&&016000.&&&&&016,000
Ctenophora Comb bearer Comb jellies Eight "comb rows" of fused cilia &&&&&&&&&&&&0100.&&&&&0100–150 extant
Cycliophora Wheel carrying Symbion Circular mouth surrounded by small cilia, sac-like bodies &&&&&&&&&&&&&&03.&&&&&03+
Echinodermata Spiny skin Echinoderms Fivefold radial symmetry in living forms, mesodermal calcified spines &&&&&&&&&&&07500.&&&&&07,500 extant; approx. 13,000 extinct
Entoprocta Goblet worms &&&&&&&&&&&&0150.&&&&&0150
Gastrotricha Hairy stomach Gastrotrich worms Two terminal adhesive tubes &&&&&&&&&&&&0690.&&&&&0690
Gnathostomulida Jaw orifice Jaw worms Tiny worms related to rotifers with no body cavity &&&&&&&&&&&&0100.&&&&&0100
Hemichordata Half cord Acorn worms, hemichordates Stomochord in collar, pharyngeal slits &&&&&&&&&&&&0130.&&&&&0130 extant
Kinorhyncha Motion snout Mud dragons Eleven segments, each with a dorsal plate &&&&&&&&&&&&0150.&&&&&0150
Loricifera Armour bearer Brush heads Umbrella-like scales at each end &&&&&&&&&&&&0122.&&&&&0122
Micrognathozoa Tiny jaw animals None Accordion-like extensible thorax &&&&&&&&&&&&&&01.&&&&&01
Mollusca Soft Mollusks / molluscs Muscular foot and mantle round shell &&&&&&&&&&085000.&&&&&085,000+ extant; 80,000+ extinct
(Nomen inquirendum)
None distinct anterior/posterior parts and being densely ciliated, especially around the "mouth". 1
Nematoda Thread like Round worms, thread worms Round cross section, keratin cuticle &&&&&&&&&&025000.&&&&&025,000
Nematomorpha Thread form Horsehair worms, Gordian worms Long, thin parasitic worms closely related to nematodes &&&&&&&&&&&&0320.&&&&&0320
Nemertea A sea nymph Ribbon worms, rhynchocoela Unsegmented worms, with a proboscis housed in a cavity derived from the coelom called the rhynchocoel &&&&&&&&&&&01200.&&&&&01,200
Onychophora Claw bearer Velvet worms Worm-like animal with legs tipped by chitinous claws &&&&&&&&&&&&0200.&&&&&0200 extant
Orthonectida Orthonectid Parasitic, microscopic, simple, wormlike organisms 20
Petalonamae Shaped like leaves None An extinct phylum from the Ediacaran. They are bottom-dwelling and immobile, shaped like leaves (frondomorphs), feathers or spindles. 3 classes, extinct
Phoronida Zeus's mistress Horseshoe worms U-shaped gut &&&&&&&&&&&&&011.&&&&&011
Placozoa Plate animals Trichoplaxes Differentiated top and bottom surfaces, two ciliated cell layers, amoeboid fiber cells in between &&&&&&&&&&&&&&04.&&&&&04+
Platyhelminthes Flat worm Flatworms Flattened worms with no body cavity. Many are parasitic. &&&&&&&&&&029500.&&&&&029,500
Porifera Pore bearer Sponges Perforated interior wall, simplest of all known animals &&&&&&&&&&010800.&&&&&010,800 extant
Priapulida Little Priapus worms &&&&&&&&&&&&&020.&&&&&020
Proarticulata Before articulates Proarticulates An extinct group of mattress-like organisms that display "glide symmetry." Found during the Ediacaran. 3 classes, extinct
Rhombozoa (Dicyemida) Lozenge animal Rhombozoans Single anteroposterior axial celled endoparasites, surrounded by ciliated cells &&&&&&&&&&&&0100.&&&&&0100+
Rotifera Wheel bearer Rotifers Anterior crown of cilia &&&&&&&&&&&02000.&&&&&02,000
Saccorhytida Saccus : "pocket" and "wrinkle" None Saccorhytus is only about 1 mm (1.3 mm) in size and is characterized by a spherical or hemispherical body with a prominent mouth. Its body is covered by a thick but flexible cuticle. It has a nodule above its mouth. Around its body are 8 openings in a truncated cone with radial folds. Considered to be a deuterostome or an early ecdysozoan. 2 species, extinct
Tardigrada Slow step Water bears, moss piglets Microscopic relatives of the arthropods, with a four segmented body and head &&&&&&&&&&&01000.&&&&&01,000
Trilobozoa Three-lobed animal Trilobozoan A taxon of mostly discoidal organisms exhibiting tricentric symmetry. All are Ediacaran-aged 18 genera, extinct
Vetulicolia Ancient dweller Vetulicolian Might possibly be a subphylum of the chordates. Their body consists of two parts: a large front part and covered with a large "mouth" and a hundred round objects on each side that have been interpreted as gills or openings near the pharynx. Their posterior pharynx consists of 7 segments. 15 species, extinct
Xenacoelomorpha Strange hollow form Subphylum Acoelomorpha and xenoturbellida Small, simple animals. Bilaterian, but lacking typical bilaterian structures such as gut cavities and circulatory systems &&&&&&&&&&&&0400.&&&&&0400+
Total: 40 1,525,000


The kingdom Plantae is defined in various ways by different biologists (see Current definitions of Plantae). All definitions include the living embryophytes (land plants), to which may be added the two green algae divisions, Chlorophyta and Charophyta, to form the clade Viridiplantae. The table below follows the influential (though contentious) Cavalier-Smith system in equating "Plantae" with Archaeplastida, a group containing Viridiplantae and the algal Rhodophyta and Glaucophyta 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 gymnosperms (i.e. including cycads, ginkgos and gnetophytes), or for conifers alone as below.

Since the first publication of the APG system in 1998, which proposed a classification of angiosperms up to the level of orders, 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.

Land plants Viridiplantae
Green algae
Other algae (Biliphyta)
Division Meaning Common name Distinguishing characteristics Species described
Anthocerotophyta Anthoceros-like plants Hornworts Horn-shaped sporophytes, no vascular system &&&&&&&&&&&&0100.&&&&&0100-300+
Bryophyta Bryum-like plants, moss plants Mosses Persistent unbranched sporophytes, no vascular system &&&&&&&&&&012000.&&&&&012,000
Charophyta Chara-like plants Charophytes &&&&&&&&&&&01000.&&&&&01,000
Chlorophyta (Yellow-)green plants Chlorophytes &&&&&&&&&&&07000.&&&&&07,000
Cycadophyta Cycas-like plants, palm-like plants Cycads Seeds, crown of compound leaves &&&&&&&&&&&&0100.&&&&&0100-200
Ginkgophyta Ginkgo-like plants Ginkgo, maidenhair tree Seeds not protected by fruit (single living species) &&&&&&&&&&&&&&01.&&&&&01 extant; 50+ extinct
Glaucophyta Blue-green plants Glaucophytes &&&&&&&&&&&&&015.&&&&&015
Gnetophyta Gnetum-like plants Gnetophytes Seeds and woody vascular system with vessels &&&&&&&&&&&&&070.&&&&&070


Lycopodium-like plants

Wolf plants

Clubmosses & spikemosses Microphyll leaves, vascular system &&&&&&&&&&&01290.&&&&&01,290 extant
Magnoliophyta Magnolia-like plants Flowering plants, angiosperms Flowers and fruit, vascular system with vessels &&&&&&&&&0300000.&&&&&0300,000


Marchantia-like plants

Liver plants

Liverworts Ephemeral unbranched sporophytes, no vascular system &&&&&&&&&&&09000.&&&&&09,000


Polypodium-like plants
Ferns Megaphyll leaves, vascular system &&&&&&&&&&010560.&&&&&010,560
Picozoa Extremely small animals Picozoans, picobiliphytes, biliphytes 1


Pinus-like plants

Cone-bearing plant

Conifers Cones containing seeds and wood composed of tracheids &&&&&&&&&&&&0629.&&&&&0629 extant
Prasinodermophyta Prasinoderma-like plants Picozoans, picobiliphytes, biliphytes 8
Rhodophyta Rose plants Red algae Use phycobiliproteins as accessory pigments. &&&&&&&&&&&07000.&&&&&07,000
Total: 14


Division Meaning Common name Distinguishing characteristics Species described
Ascomycota Bladder fungus Ascomycetes, sac fungi Tend to have fruiting bodies (ascocarp). Filamentous, producing hyphae separated by septa. Can reproduce asexually. 30,000
Basidiomycota Small base fungus Basidiomycetes, club fungi Bracket fungi, toadstools, smuts and rust. Sexual reproduction. 31,515
Blastocladiomycota Offshoot branch fungus Blastoclads Less than 200
Chytridiomycota Little cooking pot fungus Chytrids Predominantly Aquatic saprotrophic or parasitic. Have a posterior flagellum. Tend to be single celled but can also be multicellular. 1000+
Glomeromycota Ball of yarn fungus Glomeromycetes, AM fungi Mainly arbuscular mycorrhizae present, terrestrial with a small presence on wetlands. Reproduction is asexual but requires plant roots. 284
Microsporidia Small seeds Microsporans 1400
Neocallimastigomycota New beautiful whip fungus Neocallimastigomycetes Predominantly located in digestive tract of herbivorous animals. Anaerobic, terrestrial and aquatic. approx. 20
Zygomycota Pair fungus Zygomycetes Most are saprobes and reproduce sexually and asexually. approx. 1060
Total: 8

Phylum Microsporidia is generally included in kingdom Fungi, though its exact relations remain uncertain, and it is considered a protozoan by the International Society of Protistologists (see Protista, below). Molecular analysis of Zygomycota has found it to be 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 (of uncertain placement): Entomophthoromycotina, Kickxellomycotina, Mucoromycotina, and Zoopagomycotina.


{{Main|Protista taxonomy} Kingdom Protista (or Protoctista) is included in the traditional five- or six-kingdom model, where it can be defined as containing all eukaryotes that are not plants, animals, or fungi. Protista is a paraphyletic 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 and Chromista in the Cavalier-Smith system.

Protist taxonomy has long been unstable, with different approaches and definitions resulting in many competing classification schemes. Many of the phyla listed below are used by the Catalogue of Life, and correspond to the Protozoa-Chromista scheme, with updates from the latest (2022) publication by Cavalier-Smith. Other phyla are used commonly by other authors, and are adapted from the system used by the International Society of Protistologists (ISP). Some of the descriptions are based on the 2019 revision of eukaryotes by the ISP.

Stramenopiles "Chromista"
"Sarcomastigota" "Protozoa"
Orphan groups
Phylum Meaning Common name Distinguishing characteristics Species described Image
Amoebozoa Amorphous animals Amoebozoans Presence of pseudopodia for amoeboid movement, tubular cristae. &&&&&&&&&&&02400.&&&&&02,400 Amoeba proteus.jpg
Apicomplexa Apical infolds Apicomplexans, sporozoans Mostly parasitic, at least one stage of the life cycle with flattened subpellicular vesicles and a complete apical complex, non-photosynthetic apicoplast. &&&&&&&&&&&06000.&&&&&06,000 Toxoplasma gondii.jpg
Apusomonas-like animals Gliding biciliates with two or three connectors between centrioles 32 Podomonas kaiyoae C.jpg
Bigyra Two rings Stramenopiles with a double helix in ciliary transition zone Aplanonet3.jpg
Cercozoa Flagellated animal Cercozoans Defined by molecular phylogeny, lacking distinctive morphological or behavioural characters. Euglypha sp.jpg
Chromerida Chromera-like organisms Chrompodellids, chromerids, colpodellids Biflagellates, chloroplasts with four membranes, incomplete apical complex, cortical alveoli, tubular cristae. 8 Vitrella brassicaformis LM Michalek 2020.png
Funnel animals Opisthokont protists Filose pseudopods; some with a colar of microvilli surrounding a flagellum &&&&&&&&&&&&0300.&&&&&0300 Desmarella moniliformis.jpg
Ciliophora Cilia bearers Ciliates Presence of multiple cilia and a cytostome. &&&&&&&&&&&04500.&&&&&04,500 Paramecium bursaria.jpg
Cryptista Hidden Defined by molecular phylogeny, flat cristae. &&&&&&&&&&&&0246.&&&&&0246 Rhodomonas salina CCMP 322.jpg
Dinoflagellata Whirling flagellates Dinoflagellates Biflagellates with a transverse ribbon-like flagellum with multiple waves beating to the cell’s left and a longitudinal flagellum beating posteriorly with only one or few waves. &&&&&&&&&&&02957.&&&&&02,957 extant
955 fossil
CSIRO ScienceImage 6736 dinoflagellate.jpg
Endomyxa Within mucus Defined by molecular phylogeny, typically plasmodial endoparasites of other eukaryotes. Vampyrella lateritia.jpg
Early groove Heterotrophic biflagellates with ventral feeding groove. &&&&&&&&&&&&&023.&&&&&023 Stygiella incarcerata.jpg
Euglenozoa True eye animals Biflagellates, one of the two cilia inserted into an apical or subapical pocket, unique ciliary configuration. &&&&&&&&&&&02037.&&&&&02,037 extant
20 fossil
Euglenoid movement.jpg
Ochre plants, heterokont plants Heterokont algae, stramenochromes, ochrophytes, heterokontophytes Biflagellates with tripartite mastigonemes, chloroplasts with four membranes and chlorophylls a and c, tubular cristae. &&&&&&&&&&021052.&&&&&021,052 extant
2,262 fossil
Diatoms through the microscope.jpg
Haptista Fasten Thin microtubule-based appendages for feeding (haptonema in haptophytes, axopodia in centrohelids), complex mineralized scales. &&&&&&&&&&&&0517.&&&&&0517 extant
1,205 fossil
Coccolithus pelagicus 2.jpg
Hemimastigophora Incomplete or atypical flagellates Hemimastigotes Ellipsoid or vermiform phagotrophs, two slightly spiraling rows of around 12 cilia each, thecal plates below the membrane supported by microtubules and rotationally symmetrical, tubular and saccular cristae. &&&&&&&&&&&&&010.&&&&&010 Hemimastix amphikineta.png
Malawimonada Malawimonas-like organisms Malawimonads Small free-living bicilates with two kinetosomes, one or two vanes in posterior cilium. &&&&&&&&&&&&&&03.&&&&&03 Malawimonasms.jpg
Metamonada Middle monads Metamonads Anaerobic or microaerophilic, some without mitochondria; four kinetosomes per kinetid Giardia muris trophozoite SEM 11643.jpg
(often considered fungi)
Opisthokont spores Parasites with chitinous spores and extrusive host-invasion apparatus Fibrillanosema spore.jpg
Percolozoa Percolomonas-like animals Complex life cycle containing amoebae, flagellates and cysts. Naegleria fowleri lifecycle stages.JPG
Perkinsozoa Perkinsus-like animals Perkinsozoans, perkinsids Parasitic biflagellates, incomplete apical complex, formation of zoosporangia or undifferentiated cells via a hypha-like tube. &&&&&&&&&&&&&026.&&&&&026 Dinovorax pyriformis PMC5609580 fig1c.png
Provora Devouring voracious protists Defined by molecular phylogeny, free-living eukaryovorous heterotrophic biflagellates with ventral groove and extrusomes. &&&&&&&&&&&&&&07.&&&&&07 Outline drawing of Ubysseya fretuma.svg
Pseudofungi False fungi Defined by molecular phylogeny, phagotrophic heterokonts with a helical ciliary transition zone. &&&&&&&&&&&01200.&&&&&01,200 Phytophthora cactorum.jpg
Retaria Reticulopodia-bearing organisms Feeding by reticulopodia (or axopodia) typically projected through various types of skeleton, closed mitosis. &&&&&&&&&&010000.&&&&&010,000 extant
50,000 fossil
Foraminifères de Ngapali.jpg
Groove-bearing animals Aerobic flagellates (none, 1, 2 or 4 flagella) with dorsal semi-rigid pellicle of one or two submembrane dense layers, ventral feeding groove, branching ventral pseudopodia, typically filose. &&&&&&&&&&&&&040.&&&&&040+ Collodictyon telophase constrict.jpg
Telonemia Telonema-like organisms Telonemids Phagotrophic pyriform biflagellates with a unique complex cytoskeleton, tubular cristae, tripartite mastigonemes, cortical alveoli. &&&&&&&&&&&&&&07.&&&&&07 Telonema rivulare (electron micrography).jpg
Total: 26, but see below.

The number of protist phyla varies greatly from one classification to the next. The Catalogue of Life includes Rhodophyta and Glaucophyta in kingdom Plantae, but other systems consider these phyla part of Protista. In addition, less popular classification schemes unite Ochrophyta and Pseudofungi under one phylum, Gyrista, and all alveolates except ciliates in one phylum Myzozoa, later lowered in rank and included in a paraphyletic phylum Miozoa. Even within a phylum, other phylum-level ranks appear, such as the case of Bacillariophyta (diatoms) within Ochrophyta. These differences became irrelevant after the adoption of a cladistic approach by the ISP, where taxonomic ranks are excluded from the classifications after being considered superfluous and unstable. Many authors prefer this usage, which lead to the Chromista-Protozoa scheme becoming obsolete.


Currently there are 40 bacterial phyla (not including "Cyanobacteria") that have been validly published according to the Bacteriological Code

  1. Abditibacteriota
  2. Acidobacteriota, phenotypically diverse and mostly uncultured
  3. Actinomycetota, High-G+C Gram positive species
  4. Aquificota, deep-branching
  5. Armatimonadota
  6. Atribacterota
  7. Bacillota, Low-G+C Gram positive species, such as the spore-formers Bacilli (aerobic) and Clostridia (anaerobic)
  8. Bacteroidota
  9. Balneolota
  10. Bdellovibrionota
  11. Caldisericota, formerly candidate division OP5, Caldisericum exile is the sole representative
  12. Calditrichota
  13. Campylobacterota
  14. Chlamydiota
  15. Chlorobiota, green sulphur bacteria
  16. Chloroflexota, green non-sulphur bacteria
  17. Chrysiogenota, only 3 genera (Chrysiogenes arsenatis, Desulfurispira natronophila, Desulfurispirillum alkaliphilum)
  18. Coprothermobacterota
  19. Deferribacterota
  20. Deinococcota, Deinococcus radiodurans and Thermus aquaticus are "commonly known" species of this phyla
  21. Dictyoglomota
  22. Elusimicrobiota, formerly candidate division Thermite Group 1
  23. Fibrobacterota
  24. Fusobacteriota
  25. Gemmatimonadota
  26. Ignavibacteriota
  27. Kiritimatiellota
  28. Lentisphaerota, formerly clade VadinBE97
  29. Mycoplasmatota, notable genus: Mycoplasma
  30. Myxococcota
  31. Nitrospinota
  32. Nitrospirota
  33. Planctomycetota
  34. Pseudomonadota, the most well-known phylum, containing species such as Escherichia coli or Pseudomonas aeruginosa
  35. Rhodothermota
  36. Spirochaetota, species include Borrelia burgdorferi, which causes Lyme disease
  37. Synergistota
  38. Thermodesulfobacteriota
  39. Thermomicrobiota
  40. Thermotogota, deep-branching
  41. Verrucomicrobiota


Currently there are 2 phyla that have been validly published according to the Bacteriological Code

  1. Nitrososphaerota
  2. Thermoproteota, second most common archaeal phylum

Other phyla that have been proposed, but not validly named, include:

  1. "Euryarchaeota", most common archaeal phylum
  2. "Korarchaeota"
  3. "Nanoarchaeota", ultra-small symbiotes, single known species

See also

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