The spinal cord begins at the occipital bone and extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column.
Earthworms are invertebrates, lacking a skeleton. To support and shape the body, they are filled with coelomic fluid. Earthworms sometimes appear to have a belt or saddle around their bodies; this is a clitelum, a structure containing maturing eggs.
Earthworm-Nervous System. The earthworm has a simple yet sensitive nervous system. Its cerebral ganglion, or brain, is connected to the ventral nerve cord, which runs the length of its body.