Caenorhabditis

Caenorhabditis is a genus of nematodes (roundworms) in the phylum Nematoda and the family Rhabditidae. The genus includes many species, with Caenorhabditis elegans being the best studied. C. elegans is a small, transparent worm about 1 mm long that lives in soil and decaying vegetation.

Reproduction and ecology: Reproductive modes vary among species. Caenorhabditis elegans is primarily a self-fertilizing hermaphrodite with males, while other species are gonochoristic, having separate males and females. They inhabit moist soil, compost, and leaf litter in various regions, often in temperate environments.

Lifecycle and morphology: Caenorhabditis species undergo four larval molts and reach adulthood in a few days under optimal conditions. Many species can enter a dauer larva stage, a diapause form that helps survival during harsh environmental conditions.

Genetics and genomics: The genome of C. elegans is relatively small, on the order of about 100 megabases, and encodes roughly 20,000 protein-coding genes. The organism has a fully mapped cell lineage and a robust set of genetic tools, including RNA interference and targeted mutagenesis. C. elegans was the first multicellular organism to have its entire genome sequenced and remains a central model for developmental biology, neurobiology, aging, and gene function studies.

Laboratory use and significance: Caenorhabditis species are extensively used in research due to ease of culture on agar with nonpathogenic E. coli, rapid generation times, and transparent bodies that enable direct observation of development. The genus has contributed to major advances in genetics and cell biology and serves as a valuable comparative model in evolutionary biology.