Nematode worms. Fluorescent light microscopy footage of specimens of the nematode roundworm Caenorhabditis elegans. Fluorescent dyes have been used to highlight the head and internal organs (red and yellow), but this is only visible part of the way through the clip when the right sort of light is used to trigger the fluorescence. The light also triggers rapid movement by the nematode worms. Nematodes are small worms found in a range of environments worldwide. C. elegans is a transparent, soil-dwelling nematode, found in temperate climates. It feeds on bacteria, and reaches lengths of about 1 millimetre. C. elegans is used extensively in biological research. It can reproduce by self-fertilisation (resulting in identical offspring), and takes a short time to reach maturity.