Unity, Diversity, and Evolution

by Ali, Katie and Stella

The nervous system is a vast network of cells that carry and transmit messages to and from all parts of the body. It is composed of the brain, spinal cord, and sensory nerves. Together, they regulate and coordinate the body's activities.
The nervous system consists of both a central nervous system (CNS), made up of the brain and spinal cord, and a peripheral nervous system (PNS), which consists of the sensory nerves. The CNS and PNS are unified by reflex and sensory arcs.

Meet the organisms that helped us to learn more about the unity and diversity of their nervous systems.


Alfonso "Alfie" the Pig Fetus
Zeus the Frog
Mario the Crayfish
Angelica the Starfish
Olga the Perch
Fran├žois the Mussel

***One important thing to consider is the difference between nervous systems of vertebrates (pig, frog, perch) and invertebrates (crayfish, starfish, mussel). In a vertebrate nervous system, the organism has a brain with specific parts including the cerebrum, which receives sensory information from transmitted information in response to stimuli. Vertebrates have a spinal column, and thus a spinal cord inside of it, which connects signals from the periphery to the brain. In general, the nervous system of vertebrates is much more organized that that in invertebrates.

Click the links above for more information about the parts of the nervous system, to see the nervous system of an individual organism, or any of these additional pages below:

Compare and contrast the organisms
Evolution of the nervous system
Test your NERVOUS SYSTEM knowledge after reading our page with this super sweet quiz we made just for you!