The arthropod nervous system is characterized by:

• A. Dorsal nerve cord with fused ganglia
• B. Ventral nerve cord with fused ganglia
• C. Nerve net
• D. Brain only

Answer: (B)

Arthropods organize their nervous system along the belly side with a ventral nerve cord that runs the length of the body, and each body segment has a ganglion (nerve cell cluster) connected by nerve tissue. In many arthropods these segmental ganglia are fused into larger ganglia, forming a continuous ventral nerve cord. This arrangement supports coordinated control of limbs and segment-specific movements, while a brain (a pair of cerebral ganglia) sits at the front to process sensory input.

This is why the ventral nerve cord with fused ganglia best describes arthropods. The other patterns don’t fit: a dorsal nerve cord is the hallmark of chordates, a nerve net is typical of cnidarians, and having only a brain would ignore the substantial segmental nervous coordination along the ventral cord that arthropods possess.