Subclass Rhabditia is mostly composed of

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

nematode 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 bro ...

s (particularly in the Strongylida), though there are some free-living species as well (particularly in the

Rhabditida Rhabditida is an order of free-living, zooparasitic, and phytoparasitic microbivorous nematodes living in soil. The Cephalobidae, Panagrolaimidae, Steinernematidae, and Strongyloididae seem to be closer to the Tylenchia, regardless of whet ...

). Phasmids (posterior sensory structures) are well-developed, while amphids (anterior sensory structures) are poorly developed or absent in this group. In an alternate classification system, they are treated as

suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

Rhabditina, with the orders listed here being ranked as

infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

s. Also, the

Diplogasterida Diplogasterida was an order of nematodes. It was sometimes placed in a monotypic subclass Diplogasteria, but molecular phylogenetic evidence has shown it to be embedded in the family Rhabditidae (formerly Rhabditina). The confusion of having a hi ...

, which are sometimes considered a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

subclass, are probably better placed in the Rhabditia. On the other hand, the old placement of the Ascaridida in Rhabditia instead of

Spiruria Subclass Spiruria comprises mostly parasitic secernentean nematodes. In an alternate classification, they are treated as suborder Spirurina, with the orders listed here being ranked as infraorders. The Ascaridida and the Oxyurida, which includ ...

seems unwarranted. The

contain a number of families which are probably better placed in the Tylenchia; alternatively, the latter group may entirely be merged with the Rhabditia.

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 ...

(ToL) (2002b)
Nematoda
Version of 2002-JAN-01. Retrieved 2008-NOV-02.ToL (2002)

References

Protostome subclasses Parasitic nematodes {{Rhabditida-stub

See also

References