What is the body symmetry of Platyhelminthes?

• A. Bilateral
• B. Radial
• C. Asymmetrical
• D. Spherical

Answer: (A)

Bilateral symmetry means the body has a left and a right side that are mirror images along a single plane running from head to tail. Platyhelminthes, the flatworms, exhibit this arrangement, which supports directional movement and often a concentration of sensory organs at the anterior end. This head-oriented organization helps them sense their environment and navigate while living close to moist surfaces. Radial symmetry would give many planes of symmetry around a central axis, as seen in jellyfish; asymmetry lacks a consistent left-right axis (as in some sponges); and spherical symmetry implies a ball-like form with infinite symmetry planes, which does not describe flatworms. Therefore, bilateral symmetry is the correct body plan.