Nematodes
Scientific classification
Kingdom: Animalia Phylum: Nematoda Rudolphi, 1808
Classes
Adenophorea    Subclass Enoplia    Subclass Chromadoria Secernentea    Subclass Rhabditia    Subclass Spiruria    Subclass Diplogasteria    Subclass Tylenchia A roundworm taken from wet soil. ... For other uses, see Scientific classification (disambiguation). ... For other uses, see Animal (disambiguation). ... Karl Asmund Rudolphi (b. ... Subclasses Enoplia Chromadoria Adenophorea is a class of nematodes. ... Enoplia are a subclass of the roundworm species. ... Orders Monhysterida Desmoscolecida Araeolaimida Desmodorida The Chromadoria are a subclass of the class Adenophorea, (belonging to the phylum Nematoda - roundworms). ... This article needs to be wikified. ... Subclass Rhabditia, is mostly comprised of parasitic nematodes, though there are some free-living species as well. ... Orders Ascaridida Camallanida Drilonematida Spirurida Subclass Spiruria is comprised of mostly parasitic secernentean nematodes. ... Families Cylindrocorporidae Diplogasteridae Diplogasteroididae Odontopharyngidae Diplogasterida is an order of nematodes and the sole order of its subclass Diplogasteria. ...

The nematodes or roundworms (Phylum nematoda from Greek νῆμα (nema): "thread" + -ώδη -ode "like") are one of the most common phyla of animals, with over 80,000 different described species (over 15,000 are parasitic). They are ubiquitous in freshwater, marine, and terrestrial environments, where they often outnumber other animals in both individual and species counts, and are found in locations as diverse as Antarctica and oceanic trenches. Further, there are a great many parasitic forms, including pathogens in most plants, animals, and also in humans. Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... For other uses, see Animal (disambiguation). ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. ... A pathogen or infectious agent is a biological agent that causes disease or illness to its host. ...

The nematodes were originally named nematoidea by Rudolphi (1808). They were renamed nematodes by Burmeister 1837 (as a family; Leuckart 1848 and von Siebold 1848 both promoted them to the rank of order), then nematoda (Diesing 1861), though Nathan Cobb (1919) argued that they should be called nemata or nemates (and in English 'nemas' rather than 'nematodes'). After some confusion which saw the nematodes placed (often together with the horsehair worms, nematomorpha) as a class or order in various groups such as Aschelminthes, Lankester (1877) definitively promoted them to the level of phylum. Karl Asmund Rudolphi (b. ... Karl Moriz Diesing (1800–1867) was an Austrian zoologist, specializing in the study of helminthology. ... Nathan Augustus Cobb (30 June 1859 – 4 June 1932) born in Spencer, Massachusetts is known as the father of nematology in the United States. He provided the foundations for nematode taxonomy and described over 1000 different nematode species. ... Classes Nectonematoida Gordioidea Nematomorpha (sometimes called Gordiacea, and commonly known as horsehair worms or Gordian worms) are a phylum of parasitic animals which are morphologically and ecologically similar to nematode worms, hence the name. ... The Aschelminthes (sometimes Aeschelminthes), are an obsolete phylum of pseudocoelomate and other similar animals, including as classes the Nematoda, Rotifera, Gastrotricha, Kinorhyncha, and Nematomorpha, and sometimes the Priapulida and Entoprocta. ... Ray Lankester, by Leslie Ward, 1905. ... In biological taxonomy, a phylum (Greek plural: phyla) is a taxon in the rank below kingdom and above class. ...

Abundance

Of the pseudocoelomates, the nematodes are the most common. Nematodes have successfully adapted to nearly every niche from marine to fresh water, from the polar regions to the tropics, as well as the highest to the lowest of elevations. Though 20,000 species have been classified it is estimated that this number might be upwards of 500,000 if all were known.^[1]. In certain fertile areas the topsoil is estimated to contain in the billions of nematodes per acre.^[2] In the 1914 edition of the Yearbook of the United States Department of Agriculture N.A.Cobb wrote on the abundance of nematodes^[2]: Picture of Human body cavities - dorsal body cavity to the left and ventral body cavity to the right. ... Two lichens on a rock, in two different ecological niches In ecology, a niche; (pronounced nich, neesh or nish)[1] is a term describing the relational position of a species or population in its ecosystem[1]. The ecological niche; describes how an organism or population responds to the distribution of... Topsoil is the uppermost layer of soil, usually the top six to eight inches. ... One thousand million (1,000,000,000) is the natural number following 999,999,999 and preceding 1,000,000,001. ... An acre is the name of a unit of area in a number of different systems, including Imperial units and United States customary units. ... USDA redirects here. ...

Morphology

Nematodes are unsegmented, bilaterally symmetric and triploblastic protostomes with a complete digestive system. Roundworms have no circulatory or respiratory systems so they use diffusion to breathe. Although they lack a circulatory system, nutrients are transported throughout the body via fluid in the pseudocoelom. They are thin and are round in cross section. Nematodes are one of the simplest animal groups to have a complete digestive system, with a separate orifice for food intake and waste excretion, a pattern followed by all subsequent, more complex animals. The body cavity is a pseudocoelom (persistent blastula), which lacks the muscles of coelomate animals used to force food down the digestive tract. Nematodes thus depend on internal/external pressures and body movement to move food through their digestive tracts. The mouth is often surrounded by various flaps or projections used in feeding and sensation. The portion of the body past the anus or cloaca is called the "tail." As they grow, their cells get larger, but the total number is constant, called eutely. The epidermis secretes a layered cuticle made of three layers of collagen^[2] that protects the body from drying out, from digestive juices, or from other harsh environments. Although this cuticle allows movement and shape changes via a hydrostatic skeletal system, it is very inelastic so does not allow the volume of the worm to increase. Therefore, as the worm grows, it has to molt and form new cuticles. The cuticles don't allow volume to increase so as to keep hydrostatic pressure inside the organism very high. For this reason, the roundworms do not possess circular muscles (just longitudinal ones) as they're not required. This hydrostatic pressure is the reason the roundworms are round. Illustration of the different types of symmetry of Life Forms On Earth. ... Triploblastic is a condition of the ovum in which there are three primary germinal layers: the ectoderm, mesoderm, and endoderm. ... Groups Ecdysozoa Lophotrochozoa Platyzoa Protostomes (from the Greek: first the mouth) are a taxon of animals. ... what was here was sick and improperly spelled. ... diffusion (disambiguation). ... Picture of Human body cavities - dorsal body cavity to the left and ventral body cavity to the right. ... Blastulation. ... This article is about the bodily orifice. ... In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, urinary, and genital tracts of certain animal species. ... Tropocollagen triple helix. ... A hydrostatic skeleton is one in which the bodys shape and/or function is maintained by an incompressible fluid such as blood or hemolymph. ... Ecdysis is the molting of the cuticula in arthropods and related groups (Ecdysozoa). ...

Most free-living nematodes are microscopic, though a few parasitic forms can grow to over a meter in length (typically as parasites of very large animals such as whales). There are no circular muscles, so the body can only undulate from side to side. Contact with solid objects is necessary for locomotion; its thrashing motions vary from mostly to completely ineffective at swimming. For other uses of Muscles, see Muscles (disambiguation). ...

Nematodes generally eat bacteria, fungi and protozoans, although some are filter feeders. Excretion is through a separate excretory pore. Nematodes also contract bacterial infections within excretion pores. Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... Protozoa (in Greek protos = first and zoon = animal) are single-celled creatures with nuclei that show some characteristics usually associated with animals, most notably mobility and heterotrophy. ... Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. ... The kidneys are important excretory organs in vertebrates. ...

Reproduction

Reproduction is usually sexual. Males are usually smaller than females (often much smaller) and often have a characteristically bent tail for holding the female for copulation. During copulation, one or more chitinized spicules move out of the cloaca and are inserted into genital pore of the female. Amoeboid sperm crawl along the spicule into the female worm. Nematode sperm is thought to be the only eukaryotic cell without the globular protein G-actin. A pair of lions copulating in the Maasai Mara, Kenya. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Spicules Spicules are skeletal structures that occur in most sponges. ... Amoeba (Chaos diffluens) Foraminiferan (Ammonia tepida) Heliozoan (Actinophrys sol) Amoeboids are cells that move or feed by means of temporary projections, called pseudopods (false feet). ... For other uses, see Sperm (disambiguation). ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... G-Actin (PDB code: 1j6z). ...

Eggs may be embryonated or unembryonated when passed by the female, meaning that their fertilized eggs may not yet be developed. In free-living roundworms, the eggs hatch into larva, which eventually grow into adults; in parasitic roundworms, the life cycle is often much more complicated.

Nematodes have a simple nervous system, with a main nerve cord running along the ventral side. Sensory structures at the anterior end are called amphids, while sensory structures at the posterior end are called phasmids. ...

Free-living species

In free-living species, development usually consists of four molts of the cuticle during growth. Different species feed on materials as varied as algae, fungi, small animals, fecal matter, dead organisms and living tissues. Free-living marine nematodes are important and abundant members of the meiobenthos. They play an important role in the decomposition process, aid in recycling of nutrients in marine environments and are sensitive to changes in the environment caused by pollution. One roundworm of note is Caenorhabditis elegans, which lives in the soil and has found much use as a model organism. C. elegans has had its entire genome sequenced, as well as the developmental fate of every cell determined, and every neuron mapped. Introduction Meiofauna are small benthic invertebrates that live in both marine and fresh water environments. ... Binomial name Maupas, 1900 Caenorhabditis elegans (IPA: ) is a free-living nematode (roundworm), about 1 mm in length, which lives in temperate soil environments. ... A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. ...

Some Nematodes can undergo cryptobiosis. Cryptobiosis is an ametabolic state of life entered by some lower organisms in response to adverse environmental conditions such as desiccation, freezing, and oxygen deficiency. ...

Parasitic species

Parasitic forms often have quite complicated life cycles, moving between several different hosts or locations in the host's body. Infection occurs variously by eating uncooked meat with larvae in it, by entrance into unprotected cuts or directly through the skin, by transfer via blood-sucking insects, and so forth. An Anopheles stephensi mosquito obtaining a blood meal from a human host through its pointed proboscis. ...

Nematodes commonly parasitic on humans include whipworms, hookworms, pinworms, ascarids, and filarids. The species Trichinella spiralis, commonly known as the trichina worm, occurs in rats, pigs, and humans, and is responsible for the disease trichinosis. Baylisascaris usually infests wild animals but can be deadly to humans as well. Haemonchus contortus is one of the most abundant infectious agents in sheep around the world, causing great economic damage to sheep farms. In contrast, entomopathogenic nematodes parasitize insects and are considered by humans to be beneficial. Binomial name Trichuris trichiura (Linnaeus, 1771) The human Whipworm (Trichuris trichiura or Trichocephalus trichiuris), is a roundworm, which causes trichuriasis when it infects a human large intestine. ... Species Species N. americanus and A. duodenale The hookworm is a parasitic nematode worm that lives in the small intestine of its host, which may be a mammal such as a dog, cat, or human. ... The pinworm (Genus Enterobius) is a parasitic roundworm of the phylum Nematoda. ... Binomial name Ascaris lumbricoides Ascaris lumbricoides is a human parasitic roundworm, which causes ascariasis, and occurs in roughly one billion people worldwide, including four million in the US. is the largest nematode (roundworm) which parasitizes the human intestine. ... Binomial name (Owen, 1835) The species Trichinella spiralis is an important parasite, occurring in rats, pigs, and humans, and is responsible for the disease trichinosis. ... Trichinosis, also called trichinellosis, or trichiniasis, is a parasitic disease caused by eating raw or undercooked pork and wild game products infected with the larvae of a species of roundworm Trichinella spiralis, commonly called the trichina worm. ... Baylisascaris is a genus of roundworms that infest more than fifty animal species. ... Haemonchus contortus egg Haemonchus contortus, also known as red stomach worm, wire worm or Barbers pole worm, is very common parasite and one the most pathogenic nematode of ruminants. ... Nematodes emerging from a wax moth cadaver. ...

One form of nematode is entirely dependent upon the wasps which are the sole source of fig fertilization. They prey upon the wasps, riding them from the ripe fig of the wasp's birth to the fig flower of its death, where they kill the wasp, and their offspring await the birth of the next generation of wasps as the fig ripens. Species About 800, including: Ficus altissima Ficus americana Ficus aurea Ficus benghalensis- Indian Banyan Ficus benjamina- Weeping Fig Ficus broadwayi Ficus carica- Common Fig Ficus citrifolia Ficus coronata Ficus drupacea Ficus elastica Ficus godeffroyi Ficus grenadensis Ficus hartii Ficus lyrata Ficus macbrideii Ficus macrophylla- Moreton Bay Fig Ficus microcarpa- Chinese...

Plant parasitic nematodes include several groups causing severe crop losses. The most common genera are: Aphelenchoides (foliar nematodes), Meloidogyne (root-knot nematodes), Heterodera, Globodera (cyst nematodes) such as the potato cyst nematode, Nacobbus, Pratylenchus (lesion nematodes), Ditylenchus, Xiphinema, Longidorus, Trichodorus. Several phytoparasitic nematode species cause histological damages to roots, including the formation of visible galls (Meloidogyne) which are useful characters for their diagnostic in the field. Some nematode species transmit plant viruses through their feeding activity on roots. One of them is Xiphinema index, vector of GFLV (Grapevine Fanleaf Virus), an important disease of grapes. Foliar nematodes are plant parasitic roundworms in the genus Aphelenchoides. ... The potato root nematode or potato cyst nematode (PCN) is a 1-mm long roundworm that lives on the roots of plants of the Solanaceae family, such as potatoes. ...

Other nematodes attack bark and forest trees. The most important representative of this group is Bursaphelenchus xylophilus, the pine wood nematode, present in Asia and America and recently discovered in Europe.

The largest nematode ever recorded, Placentonema gigantissima, was discovered parasitizing the placenta of a sperm whale, measuring 8.5 m in length with a diameter of 0.3 mm, and containing 32 ovaries (Gubanov, 1951).

Other large nematodes include: Dioctophyma renale, the giant kidney worm, a parasite most commonly found in mink but also in dogs and humans, that can reach up to 103 cm in length.^[3] There are very few or no other articles that link to this one. ... For other uses, see Mink (disambiguation). ...

Gubanov, N.M. 1951. Dokl Akad Nauk SSSR. 1951 Apr 21;77(6):1123-5. Translated: [Giant nematoda from the placenta of Cetacea; Placentonema gigantissima nov. gen., nov. sp.].

Gardening

Soybean cyst nematode and egg

Depending on the species, a nematode may be beneficial or detrimental to a gardener's cause. Image File history File links Download high resolution version (900x600, 193 KB)Low-temperature scanning electron micrograph of soybean cyst nematode and its egg. ... Image File history File links Download high resolution version (900x600, 193 KB)Low-temperature scanning electron micrograph of soybean cyst nematode and its egg. ... Binomial name Heterodera glycines Ichinohe, 1952 The soybean cyst nematode (SCN), Heterodera glycines, plant-parasitic nematode that is a devastating pest of the soybean (Glycine max) worldwide. ...

From a gardening perspective, there are two categories of nematode: predatory ones, which will kill garden pests like cutworms, and pest nematodes, like the root-knot nematode, which attack garden plants. The term cutworm is used for the larvae of many species of moth. ... Larva of root-knot nematode, Meloidogyne incognita, magnified 500X, shown here penetrating a tomato root Root-knot nematodes are plant-parasitic nematodes from the genus Meloigogyne. ...

Predatory nematodes can be bred by soaking a specific recipe of leaves and other detritus in water, in a dark, cool place, and can even be purchased as an organic form of pest control. Detritus may refer to: In geology, detritus is the name for loose fragments of rock that have been worn away by erosion. ... Organic movement broadly refers to the organizations and individuals involved worldwide in the promotion of sustainable agriculture and organic farming, and a general opposition to agribusiness. ... A crop duster applies low-insecticide bait that is targeted against Western corn rootworms Pest control refers to the regulation or management of another species defined as a pest, usually because it is believed to be detrimental to a persons health, the ecology or the economy Pest control is...

Phylogeny

While it has recently been suggested that nematodes are related to the arthropods and priapulids and should be grouped with them in the Ecdysozoa (molting animals), there is substantial resistance within the nematology community. Grouping organisms based on behaviors is not generally accepted. While there seems to be some evolutionary connection between these phyla, the exact nature of their relationship is still being debated. Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... Priapulida (priapulid worms, or penis worms) are a phylum of marine worms with an extensible spiny proboscis. ... Phyla Scalidophora (288 species)   Priapulida (16 species)   Kinorhyncha (150 species)   Loricifera (122 species) Nematoda (20,000+ species) Nematomorpha (320 species) Panarthropoda (6,181,000-10,193,000+ species)   Onychophora (200 species)   Tardigrada (1,000+ species)   Arthropoda (6,180,000-10,192,000+ species) The Ecdysozoa are a group of protostome... This article is about evolution in biology. ...

That the roundworms have a large number of peculiar apomorphies and in many cases a parasitic lifestyle confounds analyses; the DNA sequence data hitherto analyzed is equivocal on ecdysozoan monophyly. Genetic analyses of roundworms suggest that - as is also indicated by their unique morphological features - the group has been under intense selective pressure during its early radiation, resulting apparently in accelerated rates of both morphological and molecular evolution. Until a strong phylogenetic tree based on combined evidence is produced, most agree that the Nematoda should simply be referred to as part of the Metazoa. This cladogram shows the relationship among various insect groups. ... part of a DNA sequence A DNA sequence (sometimes genetic sequence) is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, The possible letters are A, C, G, and T, representing the four nucleotide subunits of a DNA strand (adenine, cytosine, guanine... In phylogenetics, a group is monophyletic (Greek: of one race) if it consists of an inferred common ancestor and all its descendants. ... For other uses, see Natural selection (disambiguation). ... A phylogeny (or phylogenesis) is the origin and evolution of a set of organisms, usually of a species. ... Phyla Radiata Cnidaria Ctenophora - Comb jellies Bilateria Protostomia Acoelomorpha Platyhelminthes - Flatworms Nemertina - Ribbon worms Gastrotricha Gnathostomulida - Jawed worms Micrognathozoa Rotifera - Rotifers Acanthocephala Priapulida Kinorhyncha Loricifera Entoprocta Nematoda - Roundworms Nematomorpha - Horsehair worms Cycliophora Mollusca - Mollusks Sipuncula - Peanut worms Annelida - Segmented worms Tardigrada - Water bears Onychophora - Velvet worms Arthropoda - Insects, etc. ...

Cultural references

• The first episode of the children's television show Doug involves a nematode, though it is posited that the animal is purely fictional. See Doug Bags a Neematoad

• In the SpongeBob SquarePants episode Home Sweet Pineapple, nematodes eat Spongebob's pineapple house, and he is forced to find a new home. In Best Day Ever, SpongeBob leads hungry nematodes away from the Krusty Krab by playing the song "Best Day Ever" with his nose.

• The "fiery serpents" plague mentioned in Numbers 21:6-9 could very well be the parasitic nematode.^{[citation needed]}

Doug is an Emmy Award-winning American Animated Sitcom that originally aired on Nickelodeon, and starred 6th grader Douglas Yancey Funnie. ... Doug Bags a Nematoad is the very first episode of the Nickelodeon animated television series, Doug. ... This article is about the series. ... Production Order Home Sweet Pineapple is a SpongeBob SquarePants episode from season one. ... Production Order Best Day Ever is a SpongeBob SquarePants episode from season four. ...

Robustness

• Hundreds of nematode worms (C. elegans), featured in a research project on mission STS-107, survived the Space Shuttle Columbia Disaster.^[4]

The STS-107 crewmembers strike a ‘flying’ pose for their traditional in-flight crew portrait in the SPACEHAB aboard the Space Shuttle Columbia. ... For further information about Columbias mission and crew, see STS-107. ...

See also

• Toxocariasis
• Acanthocheilonema viteae
• Xiphinema List of species
• Ascariasis

Toxocariasis is a parasitic infection with the dog or cat roundworm, Toxocara canis or Toxocara cati, respectively. ... Acanthocheilonema viteae is an important parasite. ... Xiphinema is a genus of plant-parasitic roundworms. ... Binomial name Ascaris lumbricoides Linnaeus, 1758 Ascariasis is a human disease caused by the parasitic roundworm Ascaris lumbricoides. ...

References

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 41st day of the year in the Gregorian calendar. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... is the 121st day of the year (122nd in leap years) in the Gregorian calendar. ...

External links

Wikimedia Commons has media related to:

Nematoda

• http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html
• Nematode.net: Repository of parasitic nematode sequences.
• http://www.nematodes.org/
• NeMys World free-living Marine Nematodes database
• Nematode Virtual Library
• International Federation of Nematology Societies
• Society of Nematologists
• Australasian Association of Nematologists
• Research on nematodes and longevity