<P> C. elegans is unsegmented, vermiform, and bilaterally symmetrical . It has a cuticle (a tough outer covering, as an exoskeleton), four main epidermal cords, and a fluid - filled pseudocoelom (body cavity). It also has some of the same organ systems as larger animals . About one in a thousand individuals is male and the rest are hermaphrodites . The basic anatomy of C. elegans includes a mouth, pharynx, intestine, gonad, and collagenous cuticle . Like all nematodes, they have neither a circulatory nor a respiratory system . The four bands of muscles that run the length of the body are connected to a neural system that allows the muscles to move the animal's body only as dorsal bending or ventral bending, but not left or right, except for the head, where the four muscle quadrants are wired independently from one another . When a wave of dorsal / ventral muscle contractions proceeds from the back to the front of the animal, the animal is propelled backwards . When a wave of contractions is initiated at the front and proceeds posteriorly along the body, the animal is propelled forwards . Because of this dorsal / ventral bias in body bends, any normal living, moving individual tends to lie on either its left side or its right side when observed crossing a horizontal surface . A set of ridges on the lateral sides of the body cuticle, the alae, are believed to give the animal added traction during these bending motions . </P> <P> The pharynx is a muscular food pump in the head of C. elegans, which is triangular in cross-section . This grinds food and transports it directly to the intestine . A set of "valve cells" connects the pharynx to the intestine, but how this valve operates is not understood . After digestion, the contents of the intestine are released via the rectum, as is the case with all other nematodes . No direct connection exists between the pharynx and the excretory canal, which functions in the release of liquid urine . </P> <P> Males have a single - lobed gonad, a vas deferens, and a tail specialized for mating, which incorporates spicules . Hermaphrodites have two ovaries, oviducts, spermatheca, and a single uterus . </P> <P> Numerous gut granules are present in the intestine of C. elegans, the functions of which are still not fully known, as are many other aspects of this nematode, despite the many years that it has been studied . These gut granules are found in all of the Rhabditida orders . They are very similar to lysosomes in that they feature an acidic interior and the capacity for endocytosis, but they are considerably larger, reinforcing the view of their being storage organelles . A remarkable feature of the granules is that when they are observed under ultraviolet light, they react by emitting an intense blue fluorescence . Another phenomenon seen is termed' death fluorescence' . As the worms die, a dramatic burst of blue fluorescence is emitted . This death fluorescence typically takes place in an anterior to posterior wave that moves along the intestine, and is seen in both young and old worms, whether subjected to lethal injury or peacefully dying of old age . Many theories have been posited on the functions of the gut granules, with earlier ones being eliminated by later findings . They are thought to store zinc as one of their functions . Recent chemical analysis has identified the blue fluorescent material they contain as a glycosylated form of anthranilic acid (AA). The need for the large amounts of AA the many gut granules contain is questioned . One possibility is that the AA is antibacterial and used in defense against invading pathogens . Another possibility is that the granules provide photoprotection: the bursts of AA fluorescence entail the conversion of damaging UV light to relatively harmless visible light . This is seen a possible link to the melanin--containing melanosomes . </P>

Where are c. elegans found in nature and what do they eat