The nervous system of Platyhelminthes is characterized by which arrangement?

• A. Two Nerve Cords; Anterior Centralized Ganglia (Brain)
• B. Nerve Net
• C. Single Nerve Cord
• D. No Nervous System

Answer: (A)

Flatworms have a cephalized, ladder-like nervous system. Two ventral nerve cords run along the length of the body and are connected by transverse nerves, creating a ladder pattern. At the anterior end, these cords connect to a pair of cerebral ganglia that act like a simple brain, giving the animal centralized processing for sensory input and motor control. This setup is more centralized than a diffuse nerve net but not as complex as vertebrate brains. The idea of a nerve net would be too diffuse for flatworms, and a single nerve cord wouldn’t capture the paired longitudinal cords with cross-connections and an anterior ganglion.