Platyhelminthes:

Organization:  Organ level

Symmetry:  Bilateral

Coelom:  Absent

Segmentation:  Absent

Arrangement of embryonic layers: Diploblastic

Digestive system:  Incomplete (both intercellular and extracellular)

Circulatory system:  Absent

Respiratory system:  Absent

Habitat:  Endo-parasites

Sexuality: Hermaphrodite (sexes are not separate, egg and sperm are produced in same individual).

 Notochord: Absent

 Reproduction:  Sexual

Fertilization:  Internal and indirect

Excretory organ:  Flame cells for excretion and osmo-regulation.

Distinctive features:

• They are commonly called, flat worms, because they are dorso-ventrally flat.
• Parasitic forms have hooks and suckers to absorb nutrition from host.