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.
An earthworm also has the same type nervous system as a human, just like a pig. As for the circulatory system, a humanâs pumps blood to and from the body and lungs with the help of the heart, blood vessels, and arteries.A pig, however, has a heart, blood, blood vessels, lungs, and a circulatory mechanism.ody Systems of Various Organisms. All organisms in the world have a range of systems and organs in their body. Some organisms may share similar body systems while others have absolutely nothing in common. Several of those organisms include humans, pigs, crayfish, and earthworms.