Nematodes
They are also known as Roundworms.
The some examples of Nematodes are:
1. Ascaris lumbricoides (roundworm)
2. Trichinella spiralis (trichinosis)
3. Trichuris trichiura (whipworm)
Nematodes are colourless, unsegmented, lack appendages, predaceous, parasitic and may be free-living.