Caenorhabiditis elegans is a free-living (non-parasitic) species of soil nematode which makes a good model organism for biological study because it has a small genome of only six chromosomes. It also has a short generation time of about three days (at room temperature), and is easy to grow at high densities (up to 10,000 worms on one Petri dish).

C. elegans has been thoroughly studied by geneticists, developmental biologists and neurologists. The worms can be used to study genetic manipulation, gene therapy, and the molecular basis of differentiation during embryonic development. Much of the world's knowledge about aging, genetic inheritance, and the factors that control gene expression during development comes from studying this and other nematodes.

The full taxonomic classification of C. elegans is:

Kingdom Animalia
Phylum Nematoda
Class Secernentea
Subclass Rhabditia
Order Rhabditida
Family Rhabditidae
Genus Caenorhabiditis
Species Elegans

From the science dictionary at