Paraplegia is paralysis that involves loss of motor and sensory control of the trunk and two extremities. In addition, paraplegia for the most part is the result of a spinal cord injury due to an accident or other trauma. Most common accidents contain motor vehicle accidents and falls in those aged over 65.
The new species come from old ancestors of the animals that were there, over time they slowly evolved, and they adapted to that new environment.
Yes, it's important to prevent damage to the nerve cells because if they were to get damaged you could get paralyzed. When your nerve cells are damaged the signals to move different parts of your body don't make it through to the muscles which leads to paralysis.
