i) They are also called round worms.
ii) They have elongated bodies and both end of the body are pointed.
iii) Digestive system is present as a tubular straight canal.
iv) Mouth is present in anterior and anus is present in posterior.
v) Free-living nematodes are found in upper layer of soil, fresh water and in
seawater.
vi) Their common examples are Ascaris, Hook Worm, Filaria, and Trichinella etc.