Phylum Aschelminthes:
(i) Commonly known as round worms or nematodes and covered by cuticle.
(ii) Body is bilaterally symmetrical.
(iii) They are animals with elongated cylindrical and spindle-shaped body with pointed ends.
(iv) The body cavity is a false coelom called pseudocoelom.
(v) The alimentary canal lacks a muscle layer.
(vi) Respiratory organs and blood vascular systems are absent.
Example : Ascaris (Round worm), Oxyuris (Pin worm), Ancylostoma (Hook worm), Enterobius, and Rhabditis etc.