Solution:
The characters of flatworms include :
- Flatworms are bilaterally symmetrical, triploblastic and acoelomate animals with organ level of organisation.
- Specialised cells called flame cells help in osmoregulation and excretion.
- Flatworms have dorso-ventrally flattened body, hence are called flatworms.
- Fertilisation is internal and development includes many larval stage.
