Answer the following questions about planarians

1. Cephalization is the process in animals by which nervous and sensory tissues become concentrated in the "head." Animals with elongated, bilaterally symmetrical bodies have even more specialized nervous systems. Such animals exhibit cephalization, an evolutionary trend toward a clustering of sensory neurons and interneurons at the anterior (front) end. One or more nerve cords extending toward the posterior (back) end connect these structures with nerves elsewhere in the body.

2. The nervous system is more advanced than the nerve net of cnidarians and consists of a small brain and a pair of longitudinal nerves.  These longitudinal nerves branch into smaller transverse nerves  to reach the body organs.

3.  Flatworms (planaria) have an incomplete digestive system with a  single opening (same with hydra) and a large gastrovascular cavity for digestion.

4. Radial symmetry (radiata) versus bilateral symmetry (bilateria). Also, in radiata, all members of radiata are also diploblastic, but in bilateria, all members are triploblastic...