a C. elegans adult hermaphrodite

An introduction to the nematode
Caenorhabditis elegans

Mark Blaxter, Institute of Evolutionary Biology, University of Edinburgh, UK

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Caenorhabditis elegans is a
small,
freeliving,
bacteriovorous,
soil nematode.

Caenorhabditis is a member of the Rhabditidae, a large and diverse group of nematodes found in terrestrial habitats.
small: C. elegans adults are ~1 mm long.
freeliving: Some rhabditids are pathogenic to or parasitic on animals, but C. elegans does not appear to harm anything (except bacteria). It does associate with woodlice, though, probably to use them as transport hosts. Follow this link for an introduction to the C. elegans lifecycle.
bacteriovorous: In the wild, C. elegans eats many different kinds of bacteria. In the lab, C. elegans is fed on E. coli. We use a leaky uracil biosynthesis deficient mutant of E. coli to ensure that the bacteria do not outgrow the nematodes.
soil: While C. elegans is found in the soil, it is most commonly 'captured' in compost heaps and other nutrient-rich environments. It has been isolated from temperate regions world wide.

Reproduction in C. elegans

Adult C. elegans are usually self-fertilising, protandrous hermaphrodites.

self-fertilising: thus it is easy to generate homozygous mutant stocks
protandrous: the hermaphrodite gonad produces germ cells which first differentiate as sperm (circa 250 sperm are produced) and then produces eggs.
hermaphrodite: having both male and female germ cells.
In a self-fertilising population of C. elegans, fecundity is determined by hermaphrodite sperm supply.

C. elegans can form males. These are fully functional, and produce only sperm. They transfer the sperm to the female hermaphrodites during mating. Maqles are relatively rarely seen in the wild: about 0.05% of nematodes in a wild-type population are male.