The Info List - Phylum

--- Advertisement ---


In biology, a PHYLUM (/ˈfaɪləm/ ; plural : 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 or Metazoa contains approximately 35 phyla, the plant kingdom Plantae contains about 12, and the fungus kingdom Fungi
contains about 7 phyla. Current research in phylogenetics is uncovering the relationships between phyla, which are contained in larger clades , like Ecdysozoa and Embryophyta .


* 1 General description and familiar examples

* 1.1 Definition based on genetic relation * 1.2 Definition based on body plan

* 2 Known phyla

* 2.1 Animal phyla * 2.2 Plant
phyla (divisions) * 2.3 Fungal divisions * 2.4 Protista phyla (divisions) * 2.5 Bacterial phyla/divisions * 2.6 Archaeal phyla/division/kingdoms

* 3 See also * 4 Notes * 5 References * 6 External links


The term phylum was coined by Haeckel from the Greek φῦλον _phylon_, "race, stock," related to φυλή _phyle_, "tribe, clan." In plant taxonomy, 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
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.


The most important objective measure in the above definitions is the "certain degree" that defines how different organisms need to be 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 cladistics , a method in which groups are placed on a "family tree" without any formal ranking of group size.


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. Representatives of many modern phyla did not appear until long _after_ the Cambrian.



_ This section NEEDS ADDITIONAL CITATIONS FOR VERIFICATION . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed. (February 2013)_ _(Learn how and when to remove this template message )_

Protostome Bilateria



Others (Radiata or Parazoa)


Acanthocephala Thorny head Thorny-headed worms :278 Reversible spiny proboscis that bears many rows of hooked spines 7003110000000000000♠approx. 1,100

Annelida Little ring :306 Annelids Multiple circular segment 7004170000000000000♠17,000+ extant

Arthropoda Jointed foot Arthropods Segmented bodies and jointed limbs, with Chitin
exoskeleton 7006113400000000000♠1,134,000+

Arm foot :336 Lampshells :336 Lophophore and pedicle 7002300000000000000♠300-500 extant

Bryozoa Moss
animals Moss
animals, sea mats, ectoprocts :332 Lophophore, no pedicle, ciliated tentacles , anus outside ring of cilia 7003500000000000000♠5,000 extant

Chaetognatha Longhair jaw Arrow worms :342 Chitinous spines either side of head, fins 7002100000000000000♠approx. 100 extant

Chordata With a cord Chordates Hollow dorsal nerve cord , notochord , pharyngeal slits , endostyle , post-anal tail 7005100000000000000♠approx. 100,000+

Cnidaria Stinging nettle Cnidarians Nematocysts (stinging cells) 7004110000000000000♠approx. 11,000

Ctenophora Comb bearer Comb jellies :256 Eight "comb rows" of fused cilia 7002100000000000000♠approx. 100 extant

Cycliophora Wheel carrying _Symbion_ Circular mouth surrounded by small cilia, sac-like bodies 7000300000000000000♠3+

Spiny skin Echinoderms :348 Fivefold radial symmetry in living forms, mesodermal calcified spines 7003700000000000000♠approx. 7,000 extant; approx. 13,000 extinct

Entoprocta Inside anus :292 Goblet worms Anus inside ring of cilia 7002150000000000000♠approx. 150

Gastrotricha Hairy stomach :288 Gastrotrich worms Two terminal adhesive tubes 7002690000000000000♠approx. 690

Gnathostomulida Jaw orifice Jaw worms :260

7002100000000000000♠approx. 100

Hemichordata Half cord :344 Hemichordates :344 Stomochord in collar, pharyngeal slits 7002100000000000000♠approx. 100 extant

Kinorhyncha Motion snout Mud dragons Eleven segments, each with a dorsal plate 7002150000000000000♠approx. 150

Loricifera Corset bearer Brush heads Umbrella-like scales at each end 7002122000000000000♠approx. 122

Micrognathozoa Tiny jaw animals _Limnognathia_ Accordion
-like extensible thorax 7000100000000000000♠1

Mollusca Soft :320 Mollusks / molluscs Muscular foot and mantle round shell 7005112000000000000♠112,000

Nematoda Thread like Round worms, thread worms :274 Round cross section, keratin cuticle 7004250000000000000♠25,000–1,000,000

Nematomorpha Thread form :276 Horsehair worms, Gordian worms :276

7002320000000000000♠approx. 320

Nemertea A sea nymph :270 Ribbon worms, Rhynchocoela :270

7003120000000000000♠approx. 1,200

Onychophora Claw bearer Velvet worms :328 Legs tipped by chitinous claws 7002200000000000000♠approx. 200 extant

Orthonectida Straight swimming :268 Orthonectids :268 Single layer of ciliated cells surrounding a mass of sex cells 7001200000000000000♠approx. 20

Phoronida Zeus's mistress Horseshoe worms U-shaped gut 7001110000000000000♠11

Placozoa Plate animals Trichoplaxes :242 Differentiated top and bottom surfaces, two ciliated cell layers, amoeboid fiber cells in between 7000100000000000000♠1

Platyhelminthes Flat worm :262 Flatworms :262

7004250000000000000♠approx. 25,000

Porifera * Pore bearer Sponges :246 Perforated interior wall 7003500000000000000♠5,000+ extant

Priapulida Little Priapus Penis worms

7001160000000000000♠approx. 16

Rhombozoa Lozenge animal Rhombozoans :264 Single anteroposterior axial cell surrounded by ciliated cells 7001750000000000000♠75

Rotifera Wheel bearer Rotifers :282 Anterior crown of cilia 7003200000000000000♠approx. 2,000

Sipuncula Small tube Peanut worms :310 Mouth surrounded by invertible tentacles 7002144000000000000♠144–320

Tardigrada Slow step Water bears, moss piglets :324 Four-segmented body and head 7003100000000000000♠1,000+

Xenacoelomorpha Strange form without gut — Ciliated deuterostome 7000200000000000000♠2




Main article: Plant

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 Pteridophyta, while others place them both in Pteridophyta, 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 )


_ Anthoceros _-like plant Hornworts Horn-shaped sporophytes , no vascular system 7002100000000000000♠100-300+

Bryophyta _ Bryum _-like plant, moss plant Mosses Persistent unbranched sporophytes , no vascular system 7004120000000000000♠approx. 12,000

Charophyta _Chara _-like plant Charophytes

7003100000000000000♠approx. 1,000

Chlorophyta Yellow-green plant :200 Chlorophytes

7003700000000000000♠approx. 7,000

_ Cycas _-like plant, palm-like plant Cycads Seeds, crown of compound leaves 7002100000000000000♠approx. 100-200

_ Ginkgo
_-like plant Ginkgo, maidenhair tree Seeds not protected by fruit (single living species) 7000100000000000000♠only 1 extant

Glaucophyta Blue-green plant Glaucophytes


Gnetophyta _ Gnetum _-like plant Gnetophytes Seeds and woody vascular system with vessels 7001700000000000000♠approx. 70

Lycopodiophyta ,

Lycophyta _ Lycopodium _-like plant

Wolf plant Clubmosses "> _ Pteris _-like plant, fern plant Ferns ">:396 Ascomycetes, :396 sac fungi

Basidiomycota Small base fungus :402 Basidiomycetes :402

Blastocladiomycota Offshoot branch fungus Blastoclads

Little cooking pot fungus Chytrids

Glomeromycota Ball of yarn fungus :394 Glomeromycetes, AM fungi :394

Small seeds Microsporans :390

Neocallimastigomycota New beautiful whip fungus Neocallimastigomycetes

Zygomycota Pair fungus :392 Zygomycetes :392


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 article: 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. :120 Protista is a polyphyletic taxon (it includes groups not directly related to one another), 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. The phyla listed here are used for Chromista and Protozoa by the Catalogue of Life
, adapted from the system used by the International Society of Protistologists.




Amoebozoa Amorphous animal Amoebas

_Amoeba _

Bigyra Two ring


Choanozoa Funnel animal

Ciliophora Cilia bearer Ciliates



Euglenozoa True eye animal


Foraminifera Hole bearers Forams Complex shells with one or more chambers Forams


Loukozoa Groove animal



Small spore

Myzozoa Suckling animal


Slime molds

Ochrophyta Yellow plant Diatoms


Egg fungus :184 Oomycetes


Radiozoa Ray animal Radiolarians




The Catalogue of Life
includes Rhodophyta and Glaucophyta in kingdom Plantae, but other systems consider these phyla part of Protista.


Main article: Bacterial phyla

Currently there are 29 phyla accepted by List of Prokaryotic names with Standing in Nomenclature (LPSN)

* Acidobacteria , phenotipically diverse and mostly uncultured * Actinobacteria , High-G+C Gram positive species * Aquificae , only 14 thermophilic genera, deep branching * Armatimonadetes * Bacteroidetes * Caldiserica , formerly candidate division OP5, _Caldisericum exile_ is the sole representative * Chlamydiae , only 6 genera * Chlorobi
, only 7 genera, green sulphur bacteria * Chloroflexi , green non-sulphur bacteria * Chrysiogenetes , only 3 genera (_Chrysiogenes arsenatis_, _Desulfurispira natronophila_, _Desulfurispirillum alkaliphilum_) * Cyanobacteria , also known as the blue-green algae * Deferribacteres * Deinococcus-Thermus , _Deinococcus radiodurans_ and _Thermus aquaticus_ are "commonly known" species of this phyla * Dictyoglomi * Elusimicrobia , formerly candidate division Thermite Group 1 * Fibrobacteres * Firmicutes , Low-G+C Gram positive species, such as the spore-formers Bacilli (aerobic) and Clostridia (anaerobic) * Fusobacteria * Gemmatimonadetes * Lentisphaerae , formerly clade VadinBE97 * Nitrospira * Planctomycetes * Proteobacteria , the most known phyla, containing species such as _ Escherichia coli _ or _ Pseudomonas aeruginosa _ * Spirochaetes , species include _ Borrelia burgdorferi _, which causes Lyme disease * Synergistetes * Tenericutes , alternatively class Mollicutes
in phylum Firmicutes (notable genus: _ Mycoplasma _) * Thermodesulfobacteria * Thermotogae , deep branching * Verrucomicrobia


Currently there are 5 phyla accepted by List of Prokaryotic names with Standing in Nomenclature (LPSN).

* Crenarchaeota , second most common archaeal phylum * Euryarchaeota , most common archaeal phylum * Korarchaeota * Nanoarchaeota , ultra-small symbiotes, single known species * Thaumarchaeota


* Biology portal

* Cladistics * Phylogenetics
* Systematics
* Taxonomy



* ^ _A_ _B_ McNeill, J.; et al., eds. (2012). _International Code of Nomenclature for algae, fungi, and plants (Melbourne Code), Adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011_ (electronic ed.). International Association for Plant
Taxonomy. Retrieved 2017-05-14. * ^ " Life
sciences". _The American Heritage New Dictionary of Cultural Literacy_ (third ed.). Houghton Mifflin Company. 2005. Retrieved 2008-10-04. Phyla in the plant kingdom are frequently called divisions. * ^ Berg, Linda R. (2 March 2007). _Introductory Botany: Plants, People, and the Environment_ (2 ed.). Cengage Learning. p. 15. ISBN 9780534466695 . Retrieved 2012-07-23. * ^ Valentine 2004 , p. 8. * ^ Naik, V.N. (1984). _Taxonomy of Angiosperms_. Tata McGraw-Hill. p. 27. ISBN 9780074517888 . * ^ Collins AG, Valentine JW (2001). "Defining phyla: evolutionary pathways to metazoan body plans." Evol. Dev. 3: 432-442. * ^ Valentine, James W. (2004). _On the Origin of Phyla_. Chicago: University Of Chicago Press. p. 7. ISBN 0-226-84548-6 . Classifications of organisms in hierarchical systems were in use by the seventeenth and eighteenth centuries. Usually organisms were grouped according to their morphological similarities as perceived by those early workers, and those groups were then grouped according to their similarities, and so on, to form a hierarchy. * ^ _A_ _B_ _C_ _D_ _E_ Budd, G.E.; Jensen, S. (May 2000). "A critical reappraisal of the fossil record of the bilaterian phyla". _Biological Reviews_. 75 (2): 253–295. PMID 10881389 . doi :10.1111/j.1469-185X.1999.tb00046.x . Retrieved 2007-05-26. * ^ Rouse G.W. (2001). "A cladistic analysis of Siboglinidae Caullery, 1914 (Polychaeta, Annelida): formerly the phyla Pogonophora and Vestimentifera". _Zoological Journal of the Linnean Society_. 132 (1): 55–80. doi :10.1006/zjls.2000.0263 . * ^ Pawlowski J, Montoya-Burgos JI, Fahrni JF, Wüest J, Zaninetti L (October 1996). "Origin of the Mesozoa inferred from 18S rRNA gene sequences". _Mol. Biol. Evol_. 13 (8): 1128–32. PMID 8865666 . doi :10.1093/oxfordjournals.molbev.a025675 . * ^ Budd, G. E. (September 1998). "Arthropod body-plan evolution in the Cambrian with an example from anomalocaridid muscle". _Lethaia_. Blackwell Synergy. 31 (3): 197–210. doi :10.1111/j.1502-3931.1998.tb00508.x . * ^ Briggs, D. E. G. ; Fortey, R. A. (2005). "Wonderful strife: systematics, stem groups, and the phylogenetic signal of the Cambrian radiation". _Paleobiology_. 31 (2 (Suppl)): 94–112. doi :10.1666/0094-8373(2005)0312.0.CO;2 . * ^ _A_ _B_ _C_ _D_ _E_ _F_ _G_ _H_ _I_ _J_ _K_ _L_ _M_ _N_ _O_ _P_ _Q_ _R_ _S_ _T_ _U_ _V_ _W_ _X_ _Y_ _Z_ _AA_ _AB_ _AC_ _AD_ _AE_ _AF_ _AG_ _AH_ _AI_ _AJ_ _AK_ _AL_ _AM_ _AN_ _AO_ _AP_ Margulis, Lynn; Chapman, Michael J. (2009). _Kingdoms and Domains_ (4th corrected ed.). London: Academic Press. ISBN 9780123736215 . * ^ Feldkamp, S. (2002) _Modern Biology_. Holt, Rinehart, and Winston, USA. (pp. 725) * ^ Hodda, M (2011). " Phylum
Nematoda Cobb, 1932. In: Zhang, Z.-Q. (Ed.) Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness". _Zootaxa_. 3148: 63–95. * ^ Zhang, Z (2013). "Animal biodiversity: An update of classification and diversity in 2013. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013)". _Zootaxa_. 3703 (1): 5–11. doi :10.11646/zootaxa.3703.1.3 . * ^ Species
Register. "Flatworms — Phylum
Platyhelminthes". Marine Discovery Centres. Retrieved 2007-04-09. * ^ _A_ _B_ Cavalier-Smith, Thomas (22 June 2004). "Only Six Kingdoms of Life". _Proceedings: Biological Sciences_. London: Royal Society. 271 (1545): 1251–1262. access-date= requires url= (help ) * ^ Mauseth 2012 , pp. 514, 517. * ^ _A_ _B_ _C_ Cronquist, A.; A. Takhtajan; W. Zimmermann (April 1966). "On the higher taxa of Embryobionta". _Taxon_. International Association for Plant
Taxonomy (IAPT). 15 (15): 129–134. JSTOR 1217531 . doi :10.2307/1217531 . * ^ Chase, Mark W. & Reveal, James L. (October 2009), "A phylogenetic classification of the land plants to accompany APG III", _Botanical Journal of the Linnean Society_, 161 (2): 122–127, doi :10.1111/j.1095-8339.2009.01002.x * ^ Mauseth, James D. (2012). _ Botany : An Introduction to Plant Biology_ (5th ed.). Sudbury, MA: Jones and Bartlett Learning. ISBN 978-1-4496-6580-7 . p. 489 * ^ _A_ _B_ Mauseth 2012 , p. 489. * ^ Mauseth 2012 , p. 540. * ^ Mauseth 2012 , p. 542. * ^ Mauseth 2012 , p. 543. * ^ Mauseth 2012 , p. 509. * ^ Crandall-Stotler, Barbara; Stotler, Raymond E. (2000). "Morphology and classification of the Marchantiophyta". In A. Jonathan Shaw & Bernard Goffinet (Eds.). _Bryophyte Biology_. Cambridge: Cambridge University Press. p. 21. ISBN 0-521-66097-1 . CS1 maint: Uses editors parameter (link ) * ^ Mauseth 2012 , p. 535. * ^ Holt, Jack R.; Iudica, Carlos A. (1 October 2016). "Blastocladiomycota". _Diversity of Life_. Susquehanna University. Retrieved 29 December 2016. * ^ Holt, Jack R.; Iudica, Carlos A. (9 January 2014). "Chytridiomycota". _Diversity of Life_. Susquehanna University. Retrieved 29 December 2016. * ^ Holt, Jack R.; Iudica, Carlos A. (12 March 2013). "Microsporidia". _Diversity of Life_. Susquehanna University. Retrieved 29 December 2016. * ^ Holt, Jack R.; Iudica, Carlos A. (23 April 2013). "Neocallimastigomycota". _Diversity of Life_. Susquehanna University. Retrieved 29 December 2016. * ^ _A_ _B_ Hibbett DS, Binder M, Bischoff JF, Blackwell M, Cannon PF, Eriksson OE, et al. (May 2007). "A higher-level phylogenetic classification of the Fungi" (PDF). _Mycological Research_. 111 (Pt 5): 509–47. PMID 17572334 . doi :10.1016/j.mycres.2007.03.004 . * ^ _A_ _B_ Ruggiero, Michael A.; Gordon, Dennis P.; Orrell, Thomas M.; et al. (29 April 2015). "A Higher Level Classification of All Living Organisms". _PLOS One_. 10 (6). Retrieved 28 December 2016. * ^ White, Merlin M.; James, Timothy Y.; O'Donnell, Kerry; et al. (Nov–Dec 2006). "Phylogeny of the Zygomycota Based on Nuclear Ribosomal Sequence Data". _Mycologia_. Lawrence, KS: Mycological Society of America. 98 (6): 872–884. access-date= requires url= (help ) * ^ Hagen, Joel B. (January 2012). "Five Kingdoms, More or Less: Robert Whittaker and the Broad Classification of Organisms". _BioScience_. 62 (1): 67–74. * ^ Blackwell, Will H.; Powell, Martha J. (June 1999). "Reconciling Kingdoms with Codes of Nomenclature: Is It Necessary?". _Systematic Biology_. 48 (2): 406–412. * ^ Davis, R. A. (19 March 2012). "Kingdom PROTISTA". _College of Mount St. Joseph_. Retrieved 28 December 2016. * ^ _A_ _B_ "Taxonomic tree". _Catalogue of Life_. 23 December 2016. Retrieved 28 December 2016. * ^ Corliss, John O. (1984). "The Kingdom Protista and its 45 Phyla". _BioSystems_. 17: 87–176. * ^ _A_ _B_ J.P. Euzéby. "List of Prokaryotic names with Standing in Nomenclature: Phyla". Retrieved 2016-12-28.


_ Look up PHYLUM _ in Wiktionary, the free dictionary.

* Are phyla "real"? Is there really a well-defined "number of