Thread worms

the thread worms (Nematoda) and/oreingedeutscht Nematoden are one of the species-richest trunks of the animal realm. So far more than 20,000 different kinds were described.

characteristics

Nematoden are triploblastische Urmünder(Protostomia). They have a typically wurmförmige shape, long and in the cross section approximately. A segmenting is missing. The body cavity is a close Pseudocoel, as also with many other smaller animal trunks. The mouth lies in front and frequently by extensions is surrounded, thosefor food intake and for groping to be used. The Anus lies briefly before the pointed Hinterende. The epidermis separates a multi-layer Cuticula, which protects the Nematoden against drainage or other unfavorable environmental condition, with parasitischen kinds also before the digesting juicesthe landlord. The presence of a “rigid” Cutikula in connection with the longitudinal musculature (Nematoden have no ring muscles) permits them only a schlängelnde progressive movement.

to way of life

the Nematoden seem nearly everywhere, in the sea, to fresh water and in terrestrialBiotopes. Frequently are present more Nematoden after kinds and number than all other multi-cell animals (Metazoa). There is also a substantial number of parasitischer kinds, both in plants (sees about Rübenälchen) and in animals including humans. In addition belongsfor example the reeling worm (Ascaris of lumbricoides), the micro falling airs Wuchereria bancrofti and Brugia malayi, the moving falling air (Loa loa), the larva worm (Enterobius vermicularis) or the dwarf thread worm (Strongyloides stercoralis).

The Nematoden skins itself andtherefore as well as due to RNA - investigations are counted within the Urmünder (Protostomia) to the skin animals (Ecdysozoa). Most free-living Nematoden is microscopically small and belongs to the Meiofauna. Only parasites, as the horse reeling worm several meters can become long. Nematoden possessLongitudinal musculature as well as a hydraulic skeleton working antagonistically in addition. The food is different and reaches with free-living kinds of bacteria and algae over mushrooms, carrion and Fäkalien up to predatory captured animals.

reproduction

the reproduction sexually often takes placewith two separated sexes. The males are typically smaller than the females and have often a characteristically bent tail. However Hermaphroditen also fertilizing is not, like for example Caenorhabditis elegans rarity. With free-living kinds the development takes place usually directlywith four striking doing gene in the process of growth. Parasites have often a quite complicated cycle with landlord changes or organ changes in the landlord.

The infection of the landlord e.g. happens. by raw meat with larvae (Trichinen) or by admission of worm eggs inFäkalien (for example with dogs) or fäkal contaminated food (with worm eggs) due to hygiene lacking (fertilization of salad with excrement, no hand washing after chair course) in addition, can by active penetration of (to fall-air-form) larvae happened (hook worms, e.g. Ancylostoma duodenale or Necator americanus).

taxonomy

the Nematoden were originally introduced of Nathan Cobb in the year 1919 as trunk Nemata, were not classified later than class Nematoda in one any longer valid trunk Aschelminthes. Here the thread worms are led as own trunk.

• Class Adenophorea
  • Subclass Enoplia
  • subclass Chromadoria
• class Secernentea
  • subclass Rhabditia
  • subclass Spiruria
  • subclass Diplogasteria

humans and thread worms

the kind Caenorhabditis elegans became due to its simple attitude and the cell Konstanz (Eutelie) a popular “domestic animal” a Genetiker and functionedas model organism. The Nematode Pristionchus pacificus was established as satellite organism to Caenorhabditis elegans. By the comparison of these two kinds can be investigated, how itself development process - which changes transition from the egg to the adult organism in the course of the evolution.

Web on the left of

Commons: Thread worms - pictures, videos and/or audio files

• Nematode Net Nematoden systematics

• Pristionchus pacificus the WikiOnchus side Max Planck of institute for development biology [1]