Bilateral Symmetry

• A bilaterally symmetrical animal can only be cut in one vertical plane through its centre to form two mirror images
• It has a definite dorsal (top) and ventral (bottom) side, a left and right side, an anterior and a posterior end
• Development of a specialised, sensitive area, the head, at the anterior end of the body
• Concentration of nerve cells at the anterior end of the body is known as cephalisation
• A central nervous system is found which proves an advantage for locomotion