Caenorhabditis

Caenorhabditis is a genus of nematodes which live in bacteria-rich environments like compost piles and decaying dead animals. It contains the noted model organism Caenorhabditis elegans and several other species for which a genome sequence is either available or currently being determined. The two most-studied species in this genus (C. elegans and C. briggsae) are both hermaphrodites whereas all other species are gonochoristic (they have male and female sexes).^[1]

Ecology

Caenorhabditis occupy various nutrient and bacteria rich environments. They do not form self-sustaining populations in soil, as it lacks enough organic matter. Juvenile worms (dauer larvae) can be transported by invertebrates including millipedes, insects, isopods, and gastropods. Some species also appear to be associated with vertebrates including zebu cattle, although the nature of this association is not clear. The species can be classified as phoretic or necromenic based on their relationship to their invertebrate host. A phoretic worm rides on the host until it finds a favorable environment, and then leaves. A necromenic worm waits for the host to die, and lives on the bacteria which thrive in the dead animal. Many species are capable of both phoretic and necromenic lifestyles.^[2]

Species

Known species in this genus include:

• Caenorhabditis elegans - genome sequenced in 1998 ^[3]
• Caenorhabditis briggsae - genome sequence finished 2003 ^[4]
• Caenorhabditis remanei - genome sequenced by WashU GSC ^[5]

• Caenorhabditis brenneri (formerly referred to as C. sp 4 and Caenorhabditis sp. CB5161) - genome sequenced by WashU GSC ^[6]
• Caenorhabditis japonica - genome being sequenced by WashU GSC ^[7]
• Caenorhabditis sp. 3 PS1010 - genome sequenced at the California Institute of Technology in 2010 ^[8].
• Caenorhabditis drosophilae
• Caenorhabditis sp. SB341

References