Why do more scientists use Caenorhabditis elegans as a model organism to study human system?

During the last two decades , the number of scientists using Caenorhabditis elegans ( C. elegans ) as the model organism , instead of experimental animals such as rat and mice, has increased. The fields of study included gene function, embryonic development and differentiation, embryonic morphogenesis, nervous system, meiotic cell division and genes involve in programmed cell death. Moreover, C. elegans has been drastically used as model organism after the revelation of mechanism of RNA interference and the discovery of green fluorescence protein (GFP) tagged technique to trace the localization of gene expression. This article reviewed the biological data of C. elegans, as well as provided some examples of research and reasons why scientists have been using C. elegans as model organism to study the above issues.