Enoplea (enopleans) is a

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

, which with the classes

Secernentea Secernentea was a class of nematodes in the Classical Phylogeny System (Chitwood, 1958) and is no longer in use. This morphological-based classification system has been replaced by the Modern Phylogeny system, where taxonomy assignment is based o ...

Tree of Life Web Project The Tree of Life Web Project is an Internet project providing information about the diversity and phylogeny of life on Earth. This collaborative peer reviewed project began in 1995, and is written by biologists from around the world. The site h ...

(ToL) (2002)
Nematoda
Version of January 1, 2002. Retrieved November 2, 2008. and

Chromadorea The Chromadorea are a class of the roundworm phylum, Nematoda. They contain a single subclass (Chromadoria) and several orders. With such a redundant arrangement, the Chromadoria are liable to be divided if the orders are found to form several ...

make up the

phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature f ...

Nematoda The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broa ...

in current

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

. The Enoplea are considered to be a more ancestral group than the

, and researchers have referred to its members as the "ancestrally diverged nematodes", compared to the "more recently diverged nematodes" of Chromadorea.

Description

The Enoplea are distinguished from the Chromadorea by a number of characteristics. The enoplean

esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...

is cylindrical or "bottle-shaped", compared to the bulbous chromadorean esophagus. Enopleans have pocket-like

amphid Amphids (Greek: ''amphi'', around, double) are innervated invaginations of cuticle in nematodes. They are usually found in the anterior (head) region of the animal, at the base of the lips. Amphids are the principal olfactosensory organs of nematod ...

s, while chromadoreans have amphids shaped like slits, pores, coils, or spirals. An enoplean is smooth or marked with fine lines, while a chromadorean may have rings, projections, or

seta In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...

e. The enoplean

excretory system The excretory system is a passive biological system that removes excess, unnecessary materials from the body fluids of an organism, so as to help maintain internal chemical homeostasis and prevent damage to the body. The dual function of excreto ...

is simple, sometimes made up of a single cell, while chromadoreans have more complex, tubular systems, sometimes with glands.Class Enoplea.
Nemaplex: Nematode-Plant Expert Information System. University of California, Davis. Version October 9, 2012.

Taxonomy

Phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

of phylum Nematoda suggests three distinct basal

clades A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, t ...

, the

dorylaims Dorylaimia is a subclass of nematodes. Description In general, members of subclass Dorylaimia exhibit a great diversity of terrestrial and freshwater species, most of which are large predators or omnivorous free-living species. Some are plant ...

enoplids Enoplida is an order of nematodes. It is one of two orders in Enoplia, which is one of two subclasses in Class Enoplea.

and

chromadorids The Chromadorea are a class of the roundworm phylum, Nematoda. They contain a single subclass (Chromadoria) and several orders. With such a redundant arrangement, the Chromadoria are liable to be divided if the orders are found to form several c ...

. These represent Clades I, II and C+S of Blaxter (1998). Of these, the first two appear to have

sister clade In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

status, allowing resolution into two classes, Enoplea and Chromadorea, and division of the former into two subclasses corresponding to Clades I and II respectively, the Enoplia and Dorylaimia.

Subdivision

Two subclasses are divided into

orders Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

. *Subclass

Enoplia The Enoplia are a subclass of nematodes in the class Enoplea. Description Enoplians are characterized by amphids shaped like ovals, stirrups, or pouches. Their bodies are smooth, without rings or lines. The esophagus is cylindrical and gland ...

**Order

Enoplida Enoplida is an order of nematodes. It is one of two orders in Enoplia, which is one of two subclasses in Class Enoplea.

**Order Trefusiida **Order

Triplonchida Triplonchida is an order of terrestrial nematodes, and is one of two orders making up the subclass Enoplia The Enoplia are a subclass of nematodes in the class Enoplea. Description Enoplians are characterized by amphids shaped like oval ...

*Subclass

Dorylaimia Dorylaimia is a subclass of nematodes. Description In general, members of subclass Dorylaimia exhibit a great diversity of terrestrial and freshwater species, most of which are large predators or omnivorous free-living species. Some are plant ...

**Order

Dorylaimida Dorylaimida (dorylaims) is a diverse order of nematodes with both soil and freshwater species. Taxonomy History The order originated with the description of '' Dorylaimus stagnalis'' by Dujardin in 1845, and in 1876 De MAn proposed the fam ...

**Order

Mermithida Mermithida is an order of nematode worms. The order includes two families, and most members are endoparasites on arthropods. One of the morphological characteristic of the order is the presence of a stichosome.Chitwood, B. G. & Chitwood, M. B. ...

**Order

Mononchida Mononchida is an order of nematodes. Mononchid Taxonomy Order Mononchida Jairajpuri, 1969 contains two Suborders as follows: Suborder Mononchina Kirjanova and Krall, 1969 Superfamily Mononchoidea Filipjev, 1934 Family Mononchidae Flipj ...

**Order Dioctophymatida **Order

Trichinellida The Trichocephalida (Trichinellida or Trichurida in other classifications) is an order of parasitic nematodes. Taxonomy The order Trichocephalida includes, according to modern classifications, the single suborder Trichinellina Hodda, 2007, which ...

**Order Isolaimida **Order

Muspiceida Muspiceida is an order of nematodes belonging to the class Enoplea Enoplea (enopleans) is a class, which with the classes SecernenteaTree of Life Web Project (ToL) (2002)Nematoda Version of January 1, 2002. Retrieved November 2, 2008. and Ch ...

**Order Marimermithida

Ecology

Several orders of enopleans are mainly

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

animals, and several include

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

species. Many enopleans are

parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

of plants and animals, including humans. The orders Triplonchida and Dorylaimida include plant-parasitic nematodes that are vectors of plant pathogens. The orders Mermithida and Marimermithida include parasites of

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s. The orders Dioctophymatida, Trichinellida, and Muspiceida include parasites of vertebrates such as birds and mammals. Examples are ''

Trichinella spiralis ''Trichinella spiralis'' is a viviparous nematode parasite, occurring in rodents, pigs, bears, hyenas and humans, and is responsible for the disease trichinosis. It is sometimes referred to as the "pork worm" due to it being typically encounte ...

'', a nematode known for causing

trichinosis Trichinosis, also known as trichinellosis, is a parasitic disease caused by roundworms of the ''Trichinella'' type. During the initial infection, invasion of the intestines can result in diarrhea, abdominal pain, and vomiting. Migration of larv ...

in humans who consume it in undercooked

pork Pork is the culinary name for the meat of the domestic pig (''Sus domesticus''). It is the most commonly consumed meat worldwide, with evidence of pig husbandry dating back to 5000 BCE. Pork is eaten both freshly cooked and preserved; ...

, '' Haycocknema perplexum'' which can be life-threatening to humans, and

whipworms ''Trichuris trichiura, Trichocephalus trichiuris'' or whipworm, is a parasitic roundworm (a type of helminth) that causes trichuriasis (a type of helminthiasis which is one of the neglected tropical diseases) when it infects a human large intes ...

(genus ''Trichuris''), which are parasites of mammals, including cats, dogs, and humans.

References

Bibliography

* * * {{Taxonbar, from=Q1933805 Protostome classes