Arrange the following animal nervous system structures in order of increasing evolutionary complexity, from the most primitive form to the most advanced form.
- 1Diffuse nerve net without a centralized brain
- 2Ladder-like nervous system with paired cerebral ganglia
- 3Solid ventral nerve cord with segmental ganglia
- 4Dorsal hollow nerve cord with a highly specialized brain
Answer
The correct evolutionary progression from most primitive to most advanced is: Diffuse nerve net without a centralized brain, followed by Ladder-like nervous system with paired cerebral ganglia, then Solid ventral nerve cord with segmental ganglia, and finally Dorsal hollow nerve cord with a highly specialized brain.
The evolutionary trajectory of animal nervous systems progressed from decentralized nerve nets in radial organisms (cnidarians), to ladder-like systems with primitive anterior ganglia in early bilateral organisms (flatworms), to ventral nerve cords with segmental ganglia in coelomate invertebrates (annelids and arthropods), culminating in the hollow dorsal nerve cords and brain centralization characteristic of vertebrates.
Step-by-Step Solution
Key Concept
Evolutionary trend of animal nervous system centralization and cephalization.