Write a conclusion about the complication of the structure of flatworms.

Signs of a high organization of flatworms compared to coelenterates:
1. Bilateral (bilateral) symmetry associated with active movement.
2. Three layers of cells (ectoderm, mesoderm, endoderm).
3. The appearance of tissues – epithelial, connective, muscular, nervous.
4. From tissues are formed organs, from organs – systems of organs. In flatworms:
a) ladder-type nodal nervous system
b) the digestive system (protostomes)
c) excretory system – protonephridia
d) reproductive system
5. Sense organs (eyes, organs of touch).
6. Three types of muscles – longitudinal, annular, dorsal and abdominal.