Nematoda

Nematoda

The Nematoda or nematodes are a phylum of worms also known as roundworms. They are a diverse animal phylum inhabiting a broad range of environments. Nematode species can be difficult to distinguish, and although over 25,000 have been described, of which more than half are parasitic, the total number of nematode species has been estimated to be about 1 million.

Taxonomy and naming

The name Nematoda, from the Greek words νῆμα (nema, "thread") and εἶδος (eidos, "species"), was first used by Karl Rudolphi in 1808. In 1910, Nathan Cobb proposed that nematodes should be recognized alone as a phylum.

Anatomy

Nematodes have a clear tube-like digestive system, which extends from the mouth to the anus. Most nematodes possess some type of hard cuticle layer which protects their bodies from the environment.

Life cycle

The life cycle of a nematode is usually simple with the worm growing, feeding and reproducing without any need for a secondary host. Some species, however, are parasitic and require a host to complete their life cycle.

Ecology

Nematodes play crucial roles in the environment. They are involved in the decomposition process, assist in nutrient cycling and some predatory species help control the populations of other soil organisms.

Human health

Some nematodes are parasitic and can cause diseases in humans and other animals. They are a major cause of morbidity and mortality in the developing world and also cause significant problems in developed countries.

See also

• Parasitology
• Helminthiasis
• Soil life

References

Nematoda Resources
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