| Enoplea | |
|---|---|
 | |
| Mermis nigrescens | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Nematoda |
| Class: | Enoplea Inglis, 1983 |
| Subclasses | |
Enoplea (enopleans) is aclass, which with the classesSecernentea[1] andChromadorea make up thephylumNematoda in currenttaxonomy.[2][3][4] The Enoplea are considered to be a more ancestral group than theChromadorea, and researchers have referred to its members as the "ancestrally diverged nematodes", compared to the "more recently diverged nematodes" of Chromadorea.[5]
The Enoplea are distinguished from the Chromadorea by a number of characteristics. The enopleanesophagus is cylindrical or "bottle-shaped", compared to the bulbous chromadorean esophagus. Enopleans have pocket-likeamphids, 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, orsetae. The enopleanexcretory system is simple, sometimes made up of a single cell, while chromadoreans have more complex, tubular systems, sometimes with glands.[6][7]
Phylogenetic analysis of phylum Nematoda suggests three distinct basalclades, thedorylaims,enoplids andchromadorids.[8] These represent Clades I, II and C+S of Blaxter (1998).[9] Of these, the first two appear to havesister clade 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.
Two subclasses are divided intoorders.[6][8][10]
Several orders of enopleans are mainlyfreshwater animals, and several includemarine species.[11]
Many enopleans areparasites of plants and animals, including humans. The orders Triplonchida and Dorylaimida include plant-parasitic nematodes that arevectors of plant pathogens. The orders Mermithida and Marimermithida include parasites ofinvertebrates. The orders Dioctophymatida, Trichinellida, and Muspiceida include parasites of vertebrates such as birds and mammals. Examples areTrichinella spiralis, a nematode known for causingtrichinosis in humans who consume it in undercookedpork,Haycocknema perplexum which can be life-threatening to humans,[12] andwhipworms (genusTrichuris), which are parasites of mammals, including cats, dogs, and humans.[6]
