The nematode is an elegant model organism. It is fully transparent and the developmental lineage and position of each cell can be followed. They are usually hermaphrodites (i.e. it is both male and female). The adult hermaphrodite comprises exactly 959 somatic cells. Genes can be selective silenced by feeding them with plasmids expressing siRNA constructs. Their lifespan is about 2-3 weeks, but they can entire an alternative development stage and become so called DAUERs (German for sustained/endurance/continuity). DAUERs do not age.