Aschelminthes:

Organization:  Organ level

Symmetry:  Bilateral

Coelom:  Pseudo-coelomates

Segmentation:  Absent

Arrangement of embryonic layers: Triploblastic

Digestive system:  Complete

Circulatory system:  Absent

Respiratory system:  Absent

Habitat: Free-living, marine, terrestrial and parasitic.

Sexuality: Dioecious (sexes are separate).

 Notochord: Absent

 Reproduction:  Sexual

Fertilization: Internal (indirect / direct)

Excretory organ:  Excretory pore helps in excretion and osmo-regulation.

Distinctive features: 

• They are commonly called, round worms, as their body is round.
• Alimentary canal is complete with a well developed muscular pharynx.
• Females are longer than males.