Wikipedia

List of animal phyla

Wikimedia list article
(Redirected from Animal phyla)

List of animal phyla is a list of the major groups of animals usually classified as a phylum. Modern sources have been used: the list is different from that of Linnaeus or Cuvier. A list of this type may be arranged alphabetically; equally it might be arranged according to evolutionary relationships. No list will be completely satisfactory. Authorities differ in what they consider a phylum, and in the actual name of the phylum. Despite this, there is agreement on most phyla. Most modern surveys include groups above the phylum, based on evidence of common descent.

Differences of opinion about evolutionary relationships have been reduced by the use of molecular evolution and molecular clock research. These make use of protein amino acid sequences, and whole genome DNA sequence analysis. These modern techniques have led to changes and renaming of many higher categories. Classification based on traditional comparative anatomy had errors which needed to be corrected. For example, the old phylum Coelenterata, which had stood for almost two hundred years, was split down into two separate phyla, the Cnidaria and the Ctenophora.

The following list is based on evolutionary relationships:[1][2][3]

Phyla

change

Major groups in large text.

Ecdysozoa

change
  • Nematoda: the round worms. For purists, the name Nemata has priority.[4] Despite their rather limited body form, this is a major phylum, with huge numbers in every conceivable habitat. "More than 15,000 species have been described, of an estimated one million living species".[5]p90 Nematodes include both free-living and parasitic species of plants and animals, including man. Of their large number of species most are likely to be parasites.[6] Nematodes are one of the few life-forms in which each species has a defined number of cells.[7]
  • Nematomorpha: small group of nematode-like parasites. They spend their larval stage in the body cavity of arthropods. The adult stage is free, but non-feeding, though it may live for several months. About 250+ species.[5]p85
  • Priapulida or Priapula: small phylum of 18 species, with large front section which can be drawn back into the body cavity and extruded for feeding. The larger species are carnivores, seizing prey. The Burgess Shale fauna from the Cambrian shows that the living species are but a remnant of a once much larger group.[2]p358
  • Kinorhyncha: another small phylum with an introvert that carries a mouth at the end when extended.[5]p97 Two groups, described as classes in Sørensen.[8] 270 species have been described and many more are expected.[9][10]
  • Loricifera: a new phylum, discovered in the 1970s. They are microscopic, 100–485μm;[11] ~100 species. They have an exoskeleton called a lorica, and an introvert which can be withdrawn into the trunk. They live at the bottom of the water column attached to gravel. Three species live completely without oxygen. Now 37 described species, in nine genera.[12]
  • Onychophora: the velvet worms. Only 110 species from two families, they are relatives of the Arthropods.
  • Arthropoda: by far the largest phylum.[13] A recent estimate of the number of arthropods on Earth today is 3.7 million species.[14] It includes animals with jointed limbs and an exoskeleton made of chitin. There are many opinions about its classification. An arrangement found in several texts is: Superphylum Arthropoda: Phyla Chelicerata, Crustacea, Uniramia (Insects + Myriapoda).[1]p61 If Arthropoda is ranked as a phylum, its subdivisions rank as Subphyla:
  • Tardigrada: 'Water bears'. 700 species of microscopic animals from damp or aquatic habitats. Structure is constant: head, four segments, each with two legs. Terrestrial species are adapted to survive extreme conditions.

Lophotrochozoa

change
  • Sipuncula: 150 species, no certain fossil record. Small, tube-like marine animals with long tentacle-like front part which can be pulled in or out. The mouth is surrounded by a ring of cilia. Has pelagic larvae.
  • Mollusca: a great phylum by number of species and by variety of body forms; largely aquatic. Hugely important fossil record from the Lower Cambrian. A major food source for mankind, second only to fish. United by their mantle, the muscular 'foot', the radula (teeth band), and (ancestrally) by the shell. Number of living species estimated as 50,000 to 150,000. Classes: lesser classes are the Aplacophora, Monoplacophora, and Polyplacophora. Major classes are the Gastropods, Cephalopods, Bivalves and Scaphopods. A familiarity with bivalve evolution is valuable for identifying strata, so common are their fossils. Larvae are trochophores; or veligers (many gastropods & bivalves); glochidium (some freshwater bivalves).
  • Annelida: important phylum of both aquatic and terrestrial segmented worms. At least 15,000 living species. Fossil record weak, evolutionary history not well known. Classes: Polychaeta (marine worms), Oligochaeta (earthworms), Hirudinea (leeches). Larvae are trochophores or nectochaeta.
  • Bryozoa, also known as the Ectoprocta: An aquatic phylum with a huge fossil record (one of the most common in the Palaeozoic). Still fairly common, though little known to the public. There are now 5000 species, most of which build calcareous skeletons. They are almost all colonial, and all their zooids are clones.
  • Phoronida: A very small phylum, with 12 species. Live on the sea floor (benthic), build chitinous tubes covered with mud or sand or bore into calcareous rock. Usually have horeshoe-shaped lophophores with ciliated tentacles.
  • Nemertea or Nemertini: flat, unsegmented ribbon worms, mostly aquatic. They have also been called Rhynchocoela or proboscis worms. About 1400 species. There have been reports of extremely long ribbon worms, unconfirmed. Larvae are pilidiums.
  • Platyhelminthes: the flatworms. Classes: Turbellaria: free-living and aquatic (4,500 species); Trematoda: parasitic flukes of molluscs and vertebrates (~1500 species); Cestoda: tapeworms, parasitic in the digestive tract of vertebrates (3400 species); Monogenea: ectoparasites on the gills and skin of fish (1100 species). Müller's larva is characteristic of the free-living species, but in the parasitic groups development may be direct.
  • Rotifera: the rotifers. The rotifers (2200 species) are everywhere in transient pools and in sea and fresh water. The ring of cilia circling the mouth and the protective lorica are distinctive. The phylum now includes the Acanthocephala, parasitic thorn-headed worms.
  • Brachiopoda: the lamp-shells, with a huge fossil record going back to the Cambrian. 12,000 species, of which 350 are still living (or 100 according to Clarkson).[16]p158 They look rather like bivalves, and they do have an upper and lower part to the shell. However, their internal organisation is quite different.[2][17]p395 They were the dominant inshore fauna (infauna) of the Palaeozoic, but were much reduced by the two main extinction events, the P/Tr and K/T. Bivalve molluscs took over their inshore habitats in the Mesozoic, and since then the brachiopods have been confined to deeper water, except for a handful of species.
  • Entoprocta: A small phylum (150 species) of sessile benthic marine animals.
  • Gastrotricha: another phylum of small aquatic animals, with about 700 species. They are bilateral with a complete gut. They are covered with cilia, and have two terminal glands. One gland secretes cement, the other dissolves it. They have a short life span of a few days.

Deuterostomia

change
  • Xenacoelomorpha: A group of marine benthic worms consisting of 3 main lineages defined by a blind gut, a net-like nervous system, and lack of nephridia. The position of this group on the tree of life is currently debated as either the sister group to all other Bilateria[18] or as sister to all other Deuterostomia[19]
    • Xenoturbellida: Benthic marine worms, often found in the deeps sea, sizes between 2–20cm.[20]
    • Acoela: very small marine worms (usually under 2 millimeters in length) found in marine and brackish waters usually living in the benthos.
    • Nemertodermatida: small marine worms. ~11 described species. Closely related to Acoela, but differ in that unlike Acoela, they have a permanent intestinal cavity [21]
  • Echinodermata: One of the most important marine phyla, with radial symmetry. 17,000 living species, which all live in the ocean, mostly on the sea bed. This is the largest phylum which is entirely marine. The main classes are quite well-known. The Crinoids are 'sea lilies', a remnant of a once great clade; the Asterozoa are the starfish, major predators of shell-fish, and the brittle stars. The Echinozoa are the sea urchins, sand dollars and the sea cucumbers. There are also some extinct groups. The echinoderm fossil record is extensive. Larvae are varied and planktonic: pluteus (echinoids); dipleurula, then bipinneria; then brachiolaria (starfish); ophiopluteus (brittle stars); doliolaris (sea cucumbers).
  • Hemichordata: The Chordates' closest relatives, three groups which are brought together in most modern taxonomies.
    • Enteropneusta: the acorn worms. A small, well-defined group with 70 marine species. Relatives of the chordates.
    • †Graptolites: fossil colonial animals.
    • Pterobranchia: a small sub-phylum of two or three marine groups which usually build tubes, and form small colonies on sea floor. They have a long fossil record. Zooids carry prominent ciliated tentacles.
  • Chordata: the phylum which contains the vertebrates. As with the Arthropoda, some taxonomists regard this as a Superphylum, with three phyla. Here, the chordata has three sub-phyla:

Other Bilateria phyla

change
  • Cycliophora: a recently discovered group of tiny animals which live on lobsters. One genus and three species so far.
  • Gnathostomulida: jaw worms, a small phylum of small marine animals (100 species). Hermaphrodite, live in muddy benthic habitat, scape food from particles with their jaw.
  • Chaetognatha: arrow worms. Only about 120 species, but huge numbers in the plankton; some are benthic. They are predators, up to 12 cm long. They use a neurotoxin to subdue prey.
  • Orthonectida: a small phylum of parasites of marine invertebrates.

Non-Bilateria

change
  • Ctenophora: comb jellies. ~200 described species, Aquatic, all marine, usually transparent with eight comb rows of fused cilia. Mostly pelagic but several benthic species.
  • Porifera: sponges. 5000 species, aquatic mainly marine but several fresh water species, Have collared cells with long cilia. Sessile, have cell differentiation.[23] Skeleton are of spongin, or are calcareous CaCO3, or silicious SiO2.

Reflections

change

At least 21 phyla are exclusively aquatic, with several others in quasi-aquatic habitats on land. None are entirely terrestrial. This is testimony to the importance of water for life, and to the sea in particular. It is fairly certain that all phyla originated in the sea or, at any rate, in water. Most made their first showing in the Cambrian, or in the Ediacaran. Most of the soft-bodied phyla have left few fossils.

Phyla may be grouped according to evidence about their evolutionary relationships. The list above puts similar groups together.

This kind of megataxonomy is becoming more convincing as DNA sequence analysis proceeds through the phyla. Some entirely fossil groups are still placed where they are on anatomy and commonsense rather than hard molecular evidence. The trilobites are a good example. Their position in the Arthropoda is based on not much more than their bilateral symmetry and an exoskeleton. These groupings are discussed further in the references to this page.[1][2][16]

Sortable table

change

This table has the advantage of being sortable. The terminology differs in places from the above descriptions. Also, by listing living species only for most phyla, those with huge fossil records (like Bryozoa and Brachiopods) are lower in the order despite being important aquatic forms in the Palaeozoic era.

Phylum Meaning Common name Distinguishing characteristic Species described
Acanthocephala Thorny headed worms Thorny-headed worms Reversible spiny proboscis. Now usually included in Rotifera. approx. 1,329 extant (= living)
Acoelomorpha Without gut Acoels No mouth or alimentary canal (alimentary canal = digestive tract in digestive system) 483
Annelida Little ring Segmented worms Multiple circular segment 20,481+ extant
Arthropoda Jointed foot Arthropods Chitin exoskeleton 1,106,738+
Brachiopoda Arm foot Lamp shells Lophophore and pedicle 11,082 extant
Bryozoa Moss animals Moss animals, sea mats Lophophore, no pedicle, ciliated tentacles 5,609 extant
Chaetognatha Longhair jaw Arrow worms Chitinous spines either side of head, fins 132 extant
Chordata With a cord Chordates Hollow dorsal nerve cord, notochord, pharyngeal slits, endostyle, post-anal tail 65,000+
Cnidaria Stinging nettle Coelenterates Nematocysts (stinging cells) 11,791
Ctenophora Comb bearer Comb jellies Eight "comb rows" of fused cilia 210 extant
Cycliophora Wheel carrying Symbion Circular mouth surrounded by small cilia 2
Echinodermata Spiny skin Echinoderms Fivefold radial symmetry in living forms, mesodermal calcified spines 10,832
Entoprocta Inside anus Goblet worm Anus inside ring of cilia 171
Gastrotricha Hair stomach Meiofauna Two terminal adhesive tubes 851
Gnathostomulida Jaw orifice Jaw worms 101
Hemichordata Half cord Acorn worms, pterobranchs Stomochord in collar, pharyngeal slits 139
Kinorhyncha Motion snout Mud dragons Eleven segments, each with a dorsal plate 188
Loricifera Corset bearer Brush heads Umbrella-like scales at each end 27
Micrognathozoa Tiny jaw animals — Accordion-like extensible thorax. Newly discovered; close to Rotifers. 1
Mollusca Soft Mollusks / molluscs Muscular foot and mantle round shell 85,844
Nematoda Thread like Round worms Round cross section, keratin cuticle 3,452
Nematomorpha Thread form Horsehair worms 361
Nemertea A sea nymph Ribbon worms 1,351
Onychophora Claw bearer Velvet worms Legs tipped by chitinous claws 205
Orthonectida Straight swim Single layer of ciliated cells surrounding a mass of sex cells 25
Phoronida Zeus's mistress Horseshoe worms U-shaped gut 19
Placozoa Plate animals 2
Platyhelminthes Flat worms Flat worms 18,089
Porifera* Pore bearer Sponges Perforated interior wall 9,049
Priapulida Little Priapus 22
Rhombozoa Lozenge animal — Single axial cell form front to back, surrounded by ciliated cells 75
Rotifera Wheel bearer Rotifers crown of cilia at front 2,011
Sipuncula Small tube Peanut worms Mouth surrounded by invertible tentacles 205
Tardigrada Slow step Water bears Four segmented body and head 1,018
Xenoturbellida Strange flatworm — Ciliated deuterostome 4
Total: 35 1,356,899 and more species being discovered every day
Protostome Bilateria
Deuterostome
Basal/disputed
Others (Radiata or Parazoa)

Groups formerly ranked as phyla

change

This list is to help when you read older literature which may use out-of-date terms.

Name as phylum Common name Current consensus
Aschelminthes Pseudocoelomates Divided into several pseudocoelomate phyla.
Craniata — Subgroup of phylum Chordata; perhaps synonymous with Vertebrata.
Cephalochordata Lancelets Subphylum of phylum Chordata.
Cephalorhyncha — Superphylum Scalidophora.
Coelenterata — Divided into phyla Cnidaria and Ctenophora.
Echiura Spoon worms Class of phylum Annelida.
Enterepneusta Acorn worms Class of phylum Hemichordata.
Gephyra Peanut worms and spoon worms Divided into phyla Sipuncula and Echiura.
Mesozoa Mesozoans Divided into phyla Orthonectida and Rhombozoa.
Myxozoa Severely modified Cnidarians.
Pentastomida Tongue worms Subclass of Maxillopoda of phylum Arthropoda.
Pogonophora Beard worms Part of family Siboglinidae of phylum Annelida.
Pterobranchia — Class of phylum Hemichordata.
Symplasma Glass sponges Class Hexactinellida of phylum Porifera.
Urochordata Tunicates Subphylum of phylum Chordata.
Vestimentifera Vent worms Part of family Siboglinidae of phylum Annelida.

References

change
  1. ↑ 1.0 1.1 1.2 Arthur, Wallace 1997. The origin of animal body plans: a study in evolutionary developmental biology. Cambridge.
  2. ↑ 2.0 2.1 2.2 2.3 Nielsen, Claus 2001. Animal evolution: interrelationships of the living phyla. 2nd ed, Oxford.
  3. ↑ Valentine, James W. 2004. On the origin of phyla. Chicago University Press.
  4. ↑ "ITIS Standard Report Page: Nematoda". www.itis.gov.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Barnes R.S.K. Calow P. & Olive P.J.W. 1993. The invertebrates: a new synthesis. Blackwell, Oxford.
  6. ↑ See discussion in Price P.W. Evolutionary biology of parasites, p24 et seq. Princeton N.J.
  7. ↑ Abercrombie M; Hickman M; Johnson M.L. & Thain M. 1992. The Penguin dictionary of biology, 4th ed. London: Penguin Books, p388/9.
  8. ↑ Sørensen M.V. & others 2015. Phylogeny of Kinorhyncha based on morphology and two molecular loci. PLoS One 10, 1–33.
  9. ↑ Altenburger, Andreas; Rho, Hyun S.; Chang, Cheon Y.; Sørensen, Martin V. (December 2015). "Zelinkaderes yong sp. nov. from Korea – the first recording of Zelinkaderes (Kinorhyncha: Cyclorhagida) in Asia". Zoological Studies. 54 (25): e25. doi:10.1186/s40555-014-0103-6. PMC 6661445. PMID 31966112.
  10. ↑ "Species list of Kinorhyncha - Hiroshi Yamasaki website". sites.google.com. Retrieved 2018-09-20.
  11. ↑ Millionths of a metre
  12. ↑ Neves, Ricardo Cardoso; Reichert, Heinrich; Sørensen, Martin Vinther; Kristensen, Reinhardt Møbjerg (2016). "Systematics of phylum Loricifera: Identification keys of families, genera and species". Zoologischer Anzeiger. 265: 141–70. doi:10.1016/j.jcz.2016.06.002.
  13. ↑ Discussion in Grimaldi D. & Engel M.S. 2005. Evolution of the Insects. Cambridge, p646/7. ISBN 978-0-521-82149-0
  14. ↑ Counting creatures, Research highlights, Nature vol 465, 27 May 2010 p400.
  15. ↑ Barnes
  16. ↑ 16.0 16.1 Clarkson E.N.K. 1998. Invertebrate palaeontology and evolution. 4th ed, Blackwell, Oxford.
  17. ↑ Rudwick M.J.S. 1970. Living and fossil brachiopods. Hutchinson, London.
  18. ↑ Johanna Taylor Cannon, Bruno Cossermelli Vellutini, Julian 3rd Smith, Fredrik Ronquist, Ulf Jondelius & Andreas Hejnol (2016). "Xenacoelomorpha is the sister group to Nephrozoa". Nature. 530 (7588): 89–93. Bibcode:2016Natur.530...89C. doi:10.1038/nature16520. PMID 26842059. S2CID 205247296.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  19. ↑ Herve Philippe, Albert J. Poustka, Marta Chiodin, Katharina J. Hoff, Christophe Dessimoz, Bartlomiej Tomiczek, Philipp H. Schiffer, Steven Muller, Daryl Domman, Matthias Horn, Heiner Kuhl, Bernd Timmermann, Noriyuki Satoh, Tomoe Hikosaka-Katayama, Hiroaki Nakano, Matthew L. Rowe, Maurice R. Elphick, Morgane Thomas-Chollier, Thomas Hankeln, Florian Mertes, Andreas Wallberg, Jonathan P. Rast, Richard R. Copley, Pedro Martinez & Maximilian J. Telford (2019). "Mitigating Anticipated Effects of Systematic Errors Supports Sister-Group Relationship between Xenacoelomorpha and Ambulacraria". Current Biology : CB. 29 (11): 1818–1826. doi:10.1016/j.cub.2019.04.009. PMID 31104936. S2CID 155104811.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  20. ↑ Greg W. Rouse, Nerida G. Wilson, Jose I. Carvajal & Robert C. Vrijenhoek (2016). "New deep-sea species of Xenoturbella and the position of Xenacoelomorpha". Nature. 530 (7588): 94–97. Bibcode:2016Natur.530...94R. doi:10.1038/nature16545. PMID 26842060. S2CID 3870574.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ↑ Jondelius, Ulf; Ruiz-Trillo, Inaki; Baguna, Jaume; Riutort, Marta (2002). "The Nemertodermatida are basal bilaterians and not members of the Platyhelminthes". Zoologica Scripta. 31 (2): 201–215. doi:10.1046/j.1463-6409.2002.00090.x. ISSN 0300-3256. S2CID 84015834.
  22. ↑ Michael Eitel, Warren R. Francis, Frederique Varoqueaux, Jean Daraspe, Hans-Jurgen Osigus, Stefan Krebs, Sergio Vargas, Helmut Blum, Gray A. Williams, Bernd Schierwater & Gert Worheide (2018). "Comparative genomics and the nature of placozoan species". PLOS Biology. 16 (7): e2005359. doi:10.1371/journal.pbio.2005359. PMC 6067683. PMID 30063702.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  23. ↑ Cells of different types
  • Ruppert, Edward E; Fox, Richard Barnes, Robert D. 2003. Invertebrate zoology: a functional evolutionary approach. Revision of Barnes' standard textbook. 1008 pages. ISBN 978-8131501047
Retrieved from "https://simple.wikipedia.org/w/index.php?title=List_of_animal_phyla&oldid=9879484"