Phylum
Encyclopedia
In biology, a phylum (ˈfaɪləm; plural
: phyla)The term was coined by Georges Cuvier
from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank
below kingdom
and above class
. "Phylum" is equivalent to the botanical term division.
The kingdom Animalia contains approximately 35 phyla; the kingdom Plantae contains 12 divisions. Current research in phylogenetics
is uncovering the relationships between phyla, which are contained in larger clades, like Ecdysozoa
and Embryophyta.
, as well as developmental or internal organizations. For example, though seemingly divergent, spider
s and crab
s both belong to Arthropod
a, whereas earthworm
s and tapeworms
, similar in shape, are from Annelid
a and Platyhelminthes
, respectively. Although Article 3.1 of the International Code of Botanical Nomenclature allows the use of the term "phylum" in reference to plant
s, the term "division" is almost always used by botanists.
The best known animal phyla are the Mollusca
, Porifera, Cnidaria
, Platyhelminthes
, Nematoda
, Annelid
a, Arthropod
a, Echinoderm
ata, and Chordata
, the phylum to which human
s belong, along with all other vertebrate species. Although there are 35 animal phyla, these nine include over 96% of animal species. Many phyla are exclusively marine, and only one phylum, the Onychophora (velvet worms) is entirely absent from the world's ocean
s—although ancestral onycophorans were marine.
without referring to (evolutionary) relatedness is an unsatisfactory approach, but the phenetic definition is more useful when addressing questions of a morphological nature—such as how successful different body plans were.
s, these three phyla should be combined.
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. So as to provide a handle on the size and significance of groups, a "body-plan" based definition of a phylum has been proposed by paleontologists Graham Budd and Sören Jensen. The definition was posited by paleontologists because it is extinct organisms that are typically hardest to classify, because they can be extinct off-shoots that diverged from a phylum's history before the characters that define the modern phylum were all acquired.
Its utility is that 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.
Further, organisms in the stem group to a phylum can bear all the aspects of the "body plan" of the phylum without all the characters necessary to fall within it. This weakens the idea that each of the phyla represents a distinct body plan.
Based upon this definition, which some say is unreasonably affected by the chance survival of rare groups, which vastly increase the size of phyla, representatives of many modern phyla did not appear until long after the Cambrian.
Plural
In linguistics, plurality or [a] plural is a concept of quantity representing a value of more-than-one. Typically applied to nouns, a plural word or marker is used to distinguish a value other than the default quantity of a noun, which is typically one...
: phyla)The term was coined by Georges Cuvier
Georges Cuvier
Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...
from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
below kingdom
Kingdom (biology)
In biology, kingdom is a taxonomic rank, which is either the highest rank or in the more recent three-domain system, the rank below domain. Kingdoms are divided into smaller groups called phyla or divisions in botany...
and above class
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
. "Phylum" is equivalent to the botanical term division.
The kingdom Animalia contains approximately 35 phyla; the kingdom Plantae contains 12 divisions. Current research in phylogenetics
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
is uncovering the relationships between phyla, which are contained in larger clades, like Ecdysozoa
Ecdysozoa
Ecdysozoa is a group of protostome animals, including Arthropoda , Nematoda, and several smaller phyla. They were first defined by Aguinaldo et al. in 1997, based mainly on trees constructed using 18S ribosomal RNA genes...
and Embryophyta.
General description and familiar examples
Informally, phyla can be thought of as grouping organisms based on general specialization of body planBody plan
A body plan is the blueprint for the way the body of an organism is laid out. An organism's symmetry, its number of body segments and number of limbs are all aspects of its body plan...
, as well as developmental or internal organizations. For example, though seemingly divergent, spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s and crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s both belong to Arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
a, whereas earthworm
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s and tapeworms
Cestoda
This article describes the flatworm. For the medical condition, see Tapeworm infection.Cestoda is the name given to a class of parasitic flatworms, commonly called tapeworms, of the phylum Platyhelminthes. Its members live in the digestive tract of vertebrates as adults, and often in the bodies...
, similar in shape, are from Annelid
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
a and Platyhelminthes
Flatworm
The flatworms, known in scientific literature as Platyhelminthes or Plathelminthes are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals...
, respectively. Although Article 3.1 of the International Code of Botanical Nomenclature allows the use of the term "phylum" in reference to plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s, the term "division" is almost always used by botanists.
The best known animal phyla are the Mollusca
Mollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
, Porifera, Cnidaria
Cnidaria
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,...
, Platyhelminthes
Flatworm
The flatworms, known in scientific literature as Platyhelminthes or Plathelminthes are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals...
, Nematoda
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
, Annelid
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
a, Arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
a, Echinoderm
Echinoderm
Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone....
ata, and Chordata
Chordate
Chordates are animals which are either vertebrates or one of several closely related invertebrates. They are united by having, for at least some period of their life cycle, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail...
, the phylum to which human
Human
Humans are the only living species in the Homo genus...
s belong, along with all other vertebrate species. Although there are 35 animal phyla, these nine include over 96% of animal species. Many phyla are exclusively marine, and only one phylum, the Onychophora (velvet worms) is entirely absent from the world's ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
s—although ancestral onycophorans were marine.
Defining a phylum
At the most basic level, 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 hierarchyLinnaean taxonomy
Linnaean taxonomy can mean either of two related concepts:# the particular form of biological classification set up by Carl Linnaeus, as set forth in his Systema Naturæ and subsequent works...
without referring to (evolutionary) relatedness is an unsatisfactory approach, but the phenetic definition is more useful when addressing questions of a morphological nature—such as how successful different body plans were.
Definition based on genetic relation
The largest objective measure in the above definitions is the "certain degree"—how unrelated do organisms need to be to be members of different phyla? The minimal requirement is that all organisms in a phylum should be related closely enough for them to be clearly more closely related to one another than to any other group. However, even this is problematic, as the requirement depends on our current knowledge about organisms' relationships: As more data becomes available, particularly from molecular studies, we are better able to judge 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, since Onychophora and Tardigrada have now been accepted as stem groups of the arthropodArthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s, these three phyla should be combined.
This changeability of phyla has led some biologists to call for the concept of a phylum to be abandoned in favour of cladistics
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
, a method in which groups are placed on a "family tree" without any formal ranking of group size. So as to provide a handle on the size and significance of groups, a "body-plan" based definition of a phylum has been proposed by paleontologists Graham Budd and Sören Jensen. The definition was posited by paleontologists because it is extinct organisms that are typically hardest to classify, because they can be extinct off-shoots that diverged from a phylum's history before the characters that define the modern phylum were all acquired.
Definition based on body plan
By Budd and Jensen's definition, phyla are defined by a set of characters shared by all their living representatives. This has a couple of small problems—for instance, characters common to most members of a phylum may be secondarily lost by some members. It is also defined 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 more major problem is that it relies on an objective decision of which group of organisms should be considered a phylum.Its utility is that 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.
Further, organisms in the stem group to a phylum can bear all the aspects of the "body plan" of the phylum without all the characters necessary to fall within it. This weakens the idea that each of the phyla represents a distinct body plan.
Based upon this definition, which some say is unreasonably affected by the chance survival of rare groups, which vastly increase the size of phyla, representatives of many modern phyla did not appear until long after the Cambrian.
Animal phyla
| Phylum | Meaning | Common name | Distinguishing characteristic | Species described |
|---|---|---|---|---|
| Acanthocephala Acanthocephala Acanthocephala is a phylum of parasitic worms known as acanthocephales, thorny-headed worms, or spiny-headed worms, characterized by the presence of an evertable proboscis, armed with spines, which it uses to pierce and hold the gut wall of its host... |
Thorny headed worms | Thorny-headed worms | Reversible spiny proboscis Proboscis A proboscis is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In simpler terms, a proboscis is the straw-like mouth found in several varieties of species.-Etymology:... |
756 approx. |
| Acoelomorpha Acoelomorpha The Acoelomorpha are a disputed phylum of animals with planula-like features that were considered to belong to the phylum Platyhelminthes. In 2004 molecular studies demonstrated that they are a separate phylum, although their position in the tree of life is contentious; most researchers believe... |
Without gut | Acoels | No mouth or alimentary canal (alimentary canal = digestive tract in digestive system) | |
| Annelida | Little ring | Segmented worms | Multiple circular segment | 17,000+ extant |
| Arthropoda | Jointed foot | Arthropods | Chitin Chitin Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world... exoskeleton Exoskeleton An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers... |
1,134,000+ |
| Brachiopoda | Arm foot | Lamp shells | Lophophore Lophophore The lophophore is a characteristic feeding organ possessed by four major groups of animals: the Brachiopoda, Bryozoa, Entoprocta, and Phoronida. All lophophores are found in aquatic organisms.-Characteristics:... and pedicle Pedicle Pedicle or pedicel may refer to:*Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures... |
300-500 extant |
| Bryozoa Bryozoa The Bryozoa, also known as Ectoprocta or commonly as moss animals, are a phylum of aquatic invertebrate animals. Typically about long, they are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia... |
Moss animals | Moss animals, sea mats | Lophophore, no pedicle, ciliated tentacle Tentacle A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like... s |
5,000 extant |
| Chaetognatha Chaetognatha Chaetognatha, meaning hair-jaws, and commonly known as arrow worms, are a phylum of predatory marine worms that are a major component of plankton worldwide. About 20% of the known species are benthic, that is belonging to the lowest zone of the ocean, or benthic zone, and can attach to algae and... |
Longhair jaw | Arrow worms | Chitin Chitin Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world... ous spines either side of head, fins |
100 extant approx. |
| Chordata | Cord | Chordates | Hollow dorsal nerve cord Dorsal nerve cord The dorsal nerve cord is one of the embryonic features unique to chordates, along with a notochord, a post-anal tail and pharyngeal slits. The dorsal nerve cord is a hollow cord dorsal to the notochord.It is formed from a part of the ectoderm that rolls, forming the hollow tube, compared to other... , notochord Notochord The notochord is a flexible, rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body, while in most vertebrates it becomes... , pharyngeal slit Pharyngeal slit Pharyngeal slits are filter-feeding organs found in non-vertebrate chordates and hemichordates living in aquatic environments. These repeated segments are controlled by similar developmental mechanisms. Some hemichordate species can have as many as 200 gill slits... s, endostyle Endostyle An endostyle is a longitudinal ciliated groove on the ventral wall of the pharynx which produces mucus to gather food particles. It is found in urochordates and cephalochordates, and in the larvae of lampreys. It aids in transporting food to the esophagus. It is also called the hypopharyngeal groove... , post-anal Anus The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,... tail Tail The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds... |
100,000+ approx. |
| Cnidaria Cnidaria Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,... |
Stinging nettle | Coelenterates | Nematocysts (stinging cells) | 11,000 approx. |
| Ctenophora | Comb bearer | Comb jellies | Eight "comb rows" of fused cilia | 100 extant approx. |
| Cycliophora | Wheel carrying | Symbion | Circular mouth surrounded by small cilia | 3+ |
| Echinodermata | Spiny skin | Echinoderms | Fivefold radial symmetry Symmetry Symmetry generally conveys two primary meanings. The first is an imprecise sense of harmonious or aesthetically pleasing proportionality and balance; such that it reflects beauty or perfection... in living forms, mesodermal calcified spines |
7,000 extant approx.; 13,000 extinct approx. |
| Entoprocta Entoprocta Entoprocta, whose name means "anus inside", is a phylum of mostly sessile aquatic animals, ranging from long. Mature individuals are goblet-shaped, on relatively long stalks. They have a "crown" of solid tentacles whose cilia generate water currents that draw food particles towards the mouth, and... |
Inside anus Anus The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,... |
Goblet worm | Anus inside ring of cilia | 150 approx. |
| Gastrotricha | Hair stomach | Meiofauna | Two terminal adhesive tubes | 690 approx. |
| Gnathostomulida | Jaw orifice | Jaw worms | 100 approx. | |
| Hemichordata Hemichordata Hemichordata is a phylum of marine deuterostome animals, generally considered the sister group of the echinoderms. They date back to the Lower or Middle Cambrian and include two main classes: Enteropneusta , and Pterobranchia. A third class, Planctosphaeroidea, is known only from the larva of a... |
Half cord | Acorn worms, pterobranchs | Stomochord Stomochord The stomochord is a flexible, hollow tube found in hemichordates. Stomochords were initially considered a variant of a primitive notochord, but are now recognized to not share histological composition to that of the notochord found in chordates.... in collar, pharyngeal slit Pharyngeal slit Pharyngeal slits are filter-feeding organs found in non-vertebrate chordates and hemichordates living in aquatic environments. These repeated segments are controlled by similar developmental mechanisms. Some hemichordate species can have as many as 200 gill slits... s |
100 extant approx. |
| Kinorhyncha Kinorhyncha Kinorhyncha is a phylum of small marine pseudocoelomate invertebrates that are widespread in mud or sand at all depths as part of the meiobenthos... |
Motion snout | Mud dragons | Eleven segments, each with a dorsal plate | 150 approx. |
| Loricifera Loricifera Loricifera is a phylum of very small to microscopic marine sediment-dwelling animals with twenty-two described species, in eight genera. Aside from these described species, there are approximately 100 more that have been collected and not yet described. Their size ranges from 100 µm to ca.... |
Corset bearer | Brush heads | Umbrella-like scales at each end | 122 approx. |
| Micrognathozoa | Tiny jaw animals | — | Accordion Accordion The accordion is a box-shaped musical instrument of the bellows-driven free-reed aerophone family, sometimes referred to as a squeezebox. A person who plays the accordion is called an accordionist.... like extensible thorax Thorax The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:... |
1 |
| Mollusca Mollusca The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest... |
Soft | Mollusks / molluscs | Muscular foot and mantle Mantle (mollusc) The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes... round shell |
112,000 |
| Nematoda | Thread like | Round worms | Round cross section, keratin Keratin Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails... cuticle Cuticle A cuticle , or cuticula, is a term used for any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticles" are non-homologous; differing in their origin, structure, function, and chemical composition... |
80,000–1,000,000 |
| Nematomorpha Nematomorpha Nematomorpha is a phylum of parasitic animals that are superficially morphologically similar to nematode worms, hence the name. They range in size in most species from long and can reach in extreme cases up to 2 metres, and in diameter... |
Thread form | Horsehair worms | 320 approx. | |
| Nemertea Nemertea Nemertea is a phylum of invertebrate animals also known as "ribbon worms" or "proboscis worms". Alternative names for the phylum have included Nemertini, Nemertinea and Rhynchocoela. Although most are less than long, one specimen has been estimated at , which would make it the longest animal ever... |
A sea nymph | Ribbon worms | 1,200 approx. | |
| Onychophora | Claw bearer | Velvet worms | Legs tipped by chitinous claws | 200 extant approx. |
| Orthonectida Orthonectida Orthonectida is a small phylum of poorly-known parasites of marine invertebrates that are among the simplest of multi-cellular organisms. Members of this phylum are known as orthonectids.-Biology:... |
Straight swim | Single layer of ciliated cells surrounding a mass of sex cells | 20 approx. | |
| Phoronida | Zeus's mistress | Horseshoe worms | U-shaped gut | 20 |
| Placozoa | Plate animals | 1 | ||
| Platyhelminthes | Flat worms | Flat worms | 25,000 approx. | |
| Porifera* | Pore bearer | Sponges | Perforated interior wall | 5,000+ extant |
| Priapulida Priapulida Priapulida is a phylum of marine worms. They are named for their extensible spiny proboscis, which, in some species, may have a shape like that of a human penis... |
Little Priapus | 16 | ||
| Rhombozoa Rhombozoa Dicyemida, or Rhombozoa, is a phylum of tiny parasites that live in the renal appendages of cephalopods. Although the name "Dicyemida" precedes "Rhombozoa" in usage, and is preferred by most contemporary authors, "Rhombozoa" still enjoys much popular support.Classification is controversial... |
Lozenge animal | — | Single axial Axial Axial may mean:* Along the same line as an axis of rotation in geometry* A type of modal frame in music* One of several anatomical directions in an animal body* Axial age, the period from 800 to 200 BC in China, India and the western world... cell Cell (biology) The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos.... surrounded by ciliated cells |
75 |
| Rotifera | Wheel bearer | Rotifers | Anterior crown of cilia | 2,000 approx. |
| Sipuncula Sipuncula The Sipuncula or Sipunculida is a group containing 144-320 species of bilaterally symmetrical, unsegmented marine worms... |
Small tube | Peanut worms | Mouth surrounded by invertible tentacles | 144–320 |
| Tardigrada | Slow step | Water bears | Four segmented body and head | 1,000+ |
| Xenoturbellida | Strange flatworm | — | Ciliated deuterostome | 2 |
| Total: 35 | 2,000,000- |
Groups formerly ranked as phyla
| Name as phylum | Common name | Current consensus |
|---|---|---|
| Aschelminthes | Pseudocoelomates | Divided into several pseudocoelomate phyla. |
| Craniata Craniata Craniata is a proposed clade of chordate animals that contains the Myxini , Petromyzontida , and Gnathostomata as living representatives... |
— | Subgroup of phylum Chordata; perhaps synonymous with Vertebrata. |
| Cephalochordata Cephalochordata Cephalochordata is a chordate subphylum defined by the presence of a notochord that persists throughout life. It is represented in the modern oceans by the lancelets... |
Lancelets | Subphylum of phylum Chordata. |
| Cephalorhyncha | — | Superphylum Scalidophora Scalidophora Scalidophora is a group of marine pseudocoelomate invertebrates, consisting of the three phyla Kinorhyncha, Priapulida, and Loricifera. The members of the group share a number of characteristics, including introvert larvae and moulting of the cuticle... . |
| Echiura Echiura The Echiura, or spoon worms, are a small group of marine animals. They are often considered to be a group of annelids, although they lack the segmented structure found in other members of that group, and so may also be treated as a separate phylum... |
Spoon worms | Class of phylum Annelida. |
| Enterepneusta | Acorn worms | Class of phylum Hemichordata Hemichordata Hemichordata is a phylum of marine deuterostome animals, generally considered the sister group of the echinoderms. They date back to the Lower or Middle Cambrian and include two main classes: Enteropneusta , and Pterobranchia. A third class, Planctosphaeroidea, is known only from the larva of a... . |
| Gephyra | Peanut worms and spoon worms | Divided into phyla Sipuncula Sipuncula The Sipuncula or Sipunculida is a group containing 144-320 species of bilaterally symmetrical, unsegmented marine worms... and Echiura Echiura The Echiura, or spoon worms, are a small group of marine animals. They are often considered to be a group of annelids, although they lack the segmented structure found in other members of that group, and so may also be treated as a separate phylum... . |
| Mesozoa Mesozoa The Mesozoa are enigmatic, minuscule, worm-like parasites of marine invertebrates. It is still unclear as to whether they are degenerate platyhelminthes or truly-primitive, basal metazoans. Generally, these tiny, elusive creatures consist of a somatoderm of ciliated cells surrounding one or... |
Mesozoans | Divided into phyla Orthonectida Orthonectida Orthonectida is a small phylum of poorly-known parasites of marine invertebrates that are among the simplest of multi-cellular organisms. Members of this phylum are known as orthonectids.-Biology:... and Rhombozoa Rhombozoa Dicyemida, or Rhombozoa, is a phylum of tiny parasites that live in the renal appendages of cephalopods. Although the name "Dicyemida" precedes "Rhombozoa" in usage, and is preferred by most contemporary authors, "Rhombozoa" still enjoys much popular support.Classification is controversial... . |
| Myxozoa Myxozoa The Myxozoa are a group of parasitic animals of aquatic environments. Over 1300 species have been described and many have a two-host lifecycle, involving a fish and an annelid worm or bryozoan. The average size of a Myxosporea spore usually ranges from 10 μm to 20 μm and Malacosporea up... |
Severely modified Cnidarians. | |
| Pentastomida Pentastomida Pentastomida are an enigmatic group of parasitic invertebrates commonly known as tongue worms due to the resemblance of the species of the genus Linguatula to a vertebrate tongue.... |
Tongue worms | Subclass of Maxillopoda Maxillopoda Maxillopoda is a diverse class of crustaceans including barnacles, copepods and a number of related animals. It does not appear to be a monophyletic group, and no single character unites all the members.-Description:... of phylum Arthropoda. |
| Pogonophora Pogonophora There are two taxa with the name Pogonophora:*Pogonophora - an obsolete animal phylum, now treated as part of the family Siboglinidae*Pogonophora - a genus in the Euphorbiaceae... |
Beard worms | Part of family Siboglinidae Siboglinidae Siboglinidae, also known as the beard worms, is a family of polychaete annelid worms whose members made up the former phyla Pogonophora and Vestimentifera. They are composed of about 100 species of vermiform creatures and live in thin tubes buried in sediments at ocean depths from 100 to 10,000 m... of phylum Annelida. |
| Pterobranchia Pterobranchia Pterobranchia is a clade of small, worm-shaped animals. They belong to the hemichordata, and live in secreted tubes on the ocean floor. Pterobranchia feed by filtering plankton out of the water with the help of cilia attached to tentacles. There are about 30 known living species in the group.The... |
— | Class of phylum Hemichordata Hemichordata Hemichordata is a phylum of marine deuterostome animals, generally considered the sister group of the echinoderms. They date back to the Lower or Middle Cambrian and include two main classes: Enteropneusta , and Pterobranchia. A third class, Planctosphaeroidea, is known only from the larva of a... . |
| Symplasma | Glass sponges | Class Hexactinellida of phylum Porifera. |
| Urochordata | Tunicates | Subphylum of phylum Chordata. |
| Vestimentifera | Vent worms | Part of family Siboglinidae Siboglinidae Siboglinidae, also known as the beard worms, is a family of polychaete annelid worms whose members made up the former phyla Pogonophora and Vestimentifera. They are composed of about 100 species of vermiform creatures and live in thin tubes buried in sediments at ocean depths from 100 to 10,000 m... of phylum Annelida. |
Plant divisions
| Division | Meaning | Common name | Distinguishing characteristics |
| Anthocerotophyta | Flower-horn plants | Hornworts | Horn-shaped sporophyte Sporophyte All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants... s, no vascular system |
| Bryophyta Moss Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems... |
Moss plants | Mosses | Persistent unbranched sporophyte Sporophyte All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants... s, no vascular system |
| Marchantiophyta Marchantiophyta The Marchantiophyta are a division of bryophyte plants commonly referred to as hepatics or liverworts. Like other bryophytes, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information.... |
Marchantia plants | Liverworts | Ephemeral unbranched sporophyte Sporophyte All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants... s, no vascular system |
| Lycopodiophyta Lycopodiophyta The Division Lycopodiophyta is a tracheophyte subdivision of the Kingdom Plantae. It is the oldest extant vascular plant division at around 410 million years old, and includes some of the most "primitive" extant species... |
Wolf foot plants | Clubmosses & Spikemosses | Microphyll Microphyll The terminology of fossil plants is in places a little confusing. In the discipline's 200+ year history, certain concepts have become entrenched, even though improved understanding has threatened the foundations upon which they are based... leaves Leaf A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants.... , vascular system |
| Pteridophyta | Fern plants | Ferns & Horsetails | Prothallus gametophyte Gametophyte A gametophyte is the haploid, multicellular phase of plants and algae that undergo alternation of generations, with each of its cells containing only a single set of chromosomes.... s, vascular system |
| Pteridospermatophyta Pteridospermatophyta The term Pteridospermatophyta refers to several distinct groups of extinct seed-bearing plants . The oldest fossil evidence of plants of this type is of late Devonian age, and they flourished particularly during the Carboniferous and Permian periods... |
Fern with seeds plant | Seed ferns | Only known from fossils, mostly Devonian Devonian The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya... , ranking in dispute |
| Coniferophyta | Sap/pitch plants | Conifers | Cones containing seeds and wood composed of tracheids |
| Cycadophyta | Palm plants | Cycads | Seeds, crown of compound leaves |
| Ginkgophyta | Ginkgo plants | Ginkgo, Maidenhair | Seeds not protected by fruit (single species) |
| Gnetophyta Gnetophyta The plant division Gnetophyta or gnetophytes consists of three genera of woody plants grouped in the gymnosperms. The living Gnetophyta consists of around 70 species across the three genera Gnetum , Welwitschia , and Ephedra .The gnetophytes differ from other gymnosperms The plant division... |
Gnetophytes | Seeds and woody vascular system with vessels | |
| Anthophyta Flowering plant The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies... (or Magnoliophyta Flowering plant The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies... ) |
Flower plant | Flowering plants | Flowers and fruit, vascular system with vessels |
Fungal divisions
| Phylum | Meaning | Common name | Distinguishing characteristics |
| Chytridiomycota Chytridiomycota Chytridiomycota is a division of the Fungi kingdom. The name is derived from the Greek chytridion, meaning "little pot", describing the structure containing unreleased spores. In older classifications, chytrids were placed in the Class Phycomycetes under the subdivision Myxomycophyta of the... |
Little pot mushroom | Chytrids | Cellulose in cell walls, flagellated gametes |
| Deuteromycota | Second mushroom | Imperfect fungi | Unclassified fungi; only asexual reproduction observed |
| Zygomycota Zygomycota Zygomycota, or zygote fungi, is a phylum of fungi. The name comes from zygosporangia, where resistant spherical spores are formed during sexual reproduction. Approximately 1060 species are known. They are mostly terrestrial in habitat, living in soil or on decaying plant or animal material... |
Yolk mushroom | Zygomycetes | Blend gametangia Gametangia A gametangium is an organ or cell in which gametes are produced that is found in many multicellular protists, algae, fungi, and the gametophytes of plants... to form a zygosporangium |
| Glomeromycota Glomeromycota Glomeromycota is one of seven currently recognized phyla within the kingdom Fungi, with approximately 230 described species. Members of the Glomeromycota form arbuscular mycorrhizas with the roots or thalli of land plants. Geosiphon pyriformis forms an endocytobiotic association with Nostoc... |
Ball mushroom | None | Form arbuscular mycorrhizae with plants |
| Ascomycota Ascomycota The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya. Its members are commonly known as the Sac fungi. They are the largest phylum of Fungi, with over 64,000 species... |
Bag/Wineskin Mushroom | Sac fungi | Produce spores in an 'ascus Ascus An ascus is the sexual spore-bearing cell produced in ascomycete fungi. On average, asci normally contain eight ascospores, produced by a meiotic cell division followed, in most species, by a mitotic cell division. However, asci in some genera or species can number one , two, four, or multiples... ' |
| Basidiomycota Basidiomycota Basidiomycota is one of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya within the Kingdom Fungi... |
Basidium Mushroom | Club Fungi | Produce spores from a 'basidium Basidium thumb|right|500px|Schematic showing a basidiomycete mushroom, gill structure, and spore-bearing basidia on the gill margins.A basidium is a microscopic, spore-producing structure found on the hymenophore of fruiting bodies of basidiomycete fungi. The presence of basidia is one of the main... ' |
Bacterial Phyla/Divisions
Currently there are 29 phyla accepted by LPSN- AcidobacteriaAcidobacteriaAcidobacteria are a newly devised phylum of Bacteria, whose members are physiologically diverse and ubiquitous, especially in soils, but are under-represented in culture....
, phenotipically diverse and mostly uncultured - ActinobacteriaActinobacteriaActinobacteria are a group of Gram-positive bacteria with high guanine and cytosine content. They can be terrestrial or aquatic. Actinobacteria is one of the dominant phyla of the bacteria....
, High-G+C Gram positive species - AquificaeAquificaeThe Aquificae phylum is a diverse collection of bacteria that live in harsh environmental settings. They have been found in hot springs, sulfur pools, and thermal ocean vents. Members of the genus Aquifex, for example, are productive in water between 85 to 95 °C. They are the dominant members of...
, only 14 thermophilic genera, deep branching - BacteroidetesBacteroidetesThe phylum Bacteroidetes is composed of three large classes of bacteria that are widely distributed in the environment, including in soil, in sediments, sea water and in the guts and on the skin of animals....
- Caldiserica, formerly candidate division OP5, Caldisericum exile is the sole representative
- ChlamydiaeChlamydiaeChlamydiae is a bacterial phylum and class whose members are obligate intracellular pathogens. Many Chlamydiae coexist in an asymptomatic state within specific hosts, and it is widely believed that these hosts provide a natural reservoir for these species....
, only 6 genera - Chlorobi, only 7 genera
- ChloroflexiChloroflexiChloroflexi is one of four classes of bacteria in the phylum Chloroflexi, known as filamentous green non-sulfur bacteria. They produce energy from light and are named for their green pigment, usually found in photosynthetic bodies called chlorosomes....
, - Chrysiogenetes, only 3 genera (Chrysiogenes arsenatis, Desulfurispira natronophila, Desulfurispirillum alkaliphilum)
- Cyanobacteria, also known as the blue-green algae
- Deferribacteres
- Deinococcus-ThermusDeinococcus-ThermusThe Deinococcus-Thermus are a small group of bacteria composed of cocci highly resistant to environmental hazards.There are two main groups.* The Deinococcales include two families, with three genera, Deinococcus and Truepera, the former with several species that are resistant to radiation; they...
, Deinococcus radiodurans and Thermus aquaticus are "commonly known" species of this phyla - Dictyoglomi
- ElusimicrobiaElusimicrobiaThe phylum Elusimicrobia previosuly known as 'Termite Group 1' has been shown to be widespread in different ecosystems like marine environment, sewage sludge, contaminated sites and soils...
, formerly candidate division Thermite Group 1 - FibrobacteresFibrobacteresFibrobacteres is a small bacterial phylum which includes many of the major rumen bacteria, allowing for the degradation of plant-based cellulose in ruminant animals. Members of this phylum were categorized in other phyla...
- FirmicutesFirmicutesThe Firmicutes are a phylum of bacteria, most of which have Gram-positive cell wall structure. A few, however, such as Megasphaera, Pectinatus, Selenomonas and Zymophilus, have a porous pseudo-outer-membrane that causes them to stain Gram-negative...
, Low-G+C Gram positive species, such as the spore-formers BacilliBacilliBacilli refers to a taxonomic class of bacteria. It includes two orders, Bacillales and Lactobacillales, which contain several well-known pathogens like Bacillus anthracis .-Ambiguity:...
(aerobic) and ClostridiaClostridiaThe Clostridia are a class of Firmicutes, including Clostridium and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the genus Clostridium are all Gram-positive and have the ability to...
(anaerobic) - FusobacteriaFusobacteriaFusobacteria are obligately anaerobic non-sporeforming gram-negative bacilli. Since the first reports in the late nineteenth century, various names have been applied to these organisms, sometimes with the same name being applied to different species...
- GemmatimonadetesGemmatimonadetesThe Gemmatimonadetes are a family of bacteria, given their own phylum . The first member of this phylum was discovered in 2003 in activated sludge in a sewage treatment system. The bacteria was named Gemmatimonas aurantiaca and is a gram-negative rod-shaped aerobe that appears to replicate by...
- LentisphaeraeLentisphaeraeLentisphaerae is a phylum of bacteria closely related to Chlamydiae and Verrucomicrobia.It includes two monotypic orders Lentisphaerales and Victivallales. Phylum members can be aerobic or anaerobic and fall under two distinct phenotypes. One consists of terrestrial gut microbiota from mammals...
, formerly clade VadinBE97 - Nitrospira
- PlanctomycetesPlanctomycetesPlanctomycetes are a phylum of aquatic bacteria and are found in samples of brackish, and marine and fresh water. They reproduce by budding. In structure, the organisms of this group are ovoid and have a holdfast, called the stalk, at the nonreproductive end that helps them to attach to each other...
ANo ito? - ProteobacteriaProteobacteriaThe Proteobacteria are a major group of bacteria. They include a wide variety of pathogens, such as Escherichia, Salmonella, Vibrio, Helicobacter, and many other notable genera....
, the most known phyla, containing species such as Escherichia coliEscherichia coliEscherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
or Pseudomonas aeruginosaPseudomonas aeruginosaPseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many... - Spirochaetes, species include Borrelia burgdorferiBorrelia burgdorferiBorrelia burgdorferi is a species of Gram negative bacteria of the spirochete class of the genus Borrelia. B. burgdorferi is predominant in North America, but also exists in Europe, and is the agent of Lyme disease....
, which causes Lyme disease - SynergistetesSynergistetesSynergistetes is a phylum of bacteria. Members are Gram-negative,rod-shaped obligate anaerobes. Species within this phylum have been implicated in periodontal disease, gastrointestinal infections and soft tissue infections.- Phylogeny:...
- TenericutesTenericutesTenericutes is a phylum of bacteria that contains the Class Mollicutes. The name was validated in 1984 as a new division ....
, alternatively class MollicutesMollicutesThe Mollicutes are a class of bacteria distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin mollis , and cutis . They are parasites of various animals and plants, living on or in the host's cells. Individuals are very small, typically only 0.2–0.3 μm in size...
in phylum FirmicutesFirmicutesThe Firmicutes are a phylum of bacteria, most of which have Gram-positive cell wall structure. A few, however, such as Megasphaera, Pectinatus, Selenomonas and Zymophilus, have a porous pseudo-outer-membrane that causes them to stain Gram-negative...
(notable genus: MycoplasmaMycoplasmaMycoplasma refers to a genus of bacteria that lack a cell wall. Without a cell wall, they are unaffected by many common antibiotics such as penicillin or other beta-lactam antibiotics that target cell wall synthesis. They can be parasitic or saprotrophic. Several species are pathogenic in humans,...
) - ThermodesulfobacteriaThermodesulfobacteriaThe Thermodesulfobacteria are a phylum of thermophilic sulfate-reducing bacteria.-Phylogeny:The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature and the phylogeny is based on 16S rRNA-based LTP release 106 by The All-Species Living Tree Project...
- ThermomicrobiaThermomicrobiaThe Thermomicrobia are a group of thermophilic green non-sulfur bacteria. Until 2004, they were classified as a distinct phylum. It has recently been proposed, on the basis of an analysis of genetic affiliations, that the Thermomicrobia should more properly be reclassified as a class belonging to...
- ThermotogaeThermotogaeThermotogae is a phylum of the domain "Bacteria". This phylum comprises merely the class "Thermotogae", with the order "Thermotogales" and the family "Thermotogaceae"....
, deep branching - VerrucomicrobiaVerrucomicrobiaVerrucomicrobia is a recently described phylum of bacteria. This phylum contains only a few described species . The species identified have been isolated from fresh water and soil environments and human feces...
Archaeal Phyla/Division
- CrenarchaeotaCrenarchaeotaIn taxonomy, the Crenarchaeota has been classified as either a phylum of the Archaea kingdom or a kingdom of its own...
, Second most common archaeal phylum - EuryarchaeotaEuryarchaeotaIn the taxonomy of microorganisms, the Euryarchaeota are a phylum of the Archaea.The Euryarchaeota include the methanogens, which produce methane and are often found in intestines, the halobacteria, which survive extreme concentrations of salt, and some extremely thermophilic aerobes and anaerobes...
, most common archaeal phylum - KorarchaeotaKorarchaeotaIn taxonomy, the Korarchaeota are a phylum of the Archaea.Analysis of their 16S rRNA gene sequences suggests that they are a deeply-branching lineage that does not belong to the main archaeal groups, Crenarchaeota and Euryarchaeota...
- NanoarchaeotaNanoarchaeotaIn taxonomy, the Nanoarchaeota are a phylum of the Archaea. This phylum currently has only one representative, Nanoarchaeum equitans.-External links:...
, ultra-small symbiotes - ThaumarchaeotaThaumarchaeotaIn taxonomy, the Thaumarchaeota are a newly-proposed phylum of the Archaea, containing so far four species, Nitrosopumilus maritimus, Cenarchaeum symbiosum, Nitrososphaera viennensis, and Nitrososphaera gargensis...
See also
- CladisticsCladisticsCladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
- PhylogeneticsPhylogeneticsIn biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
- SystematicsSystematicsBiological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...
- TaxonomyTaxonomyTaxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...