CBSE Class 9 Answered

Platyhelminthes includes acoelomate animals whereas Aschelminthes includes pseudocoelomate animals.

Anus is absent in Platyhelminthes whereas anus is present in the animals of Aschelminthes.

The animals belonging to Platyhelminthes are hermaphrodites whereas those belonging to Aschelminthes show separate sexes.

Animals belonging to Platyhelminthes are dorsoventrally flattened whereas the animals belonging to Aschelminthes may be worm-like, cylindrical or flattened.

Features of Mollusca:

i) Body soft.

ii) Bilaterally symmetrical.

iii) Body divisible into head, foot and visceral mass.

iv) Body covered by mantle which secretes hard calcareous shell.

v) Haemocoel present.

vi) Respiration by ctenidia or mantle.

vii) Excretion carried out by kidneys or metanephridia.

viii) Sexes usually separate.

ix) They are mostly aquatic, some are terrestrial.