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.
Systems of the human body. Skin and nails are part of the integumentary system that helps protect the body. Earthworms have organ systems that help them move, breathe, and digest food. The endocrine system is responsible for producing and regulating hormones in the bloodstream to control bodily functions.he torso houses many of the human body's organ systems. The gonads are the organs that produce gametes, or the body's sex cells. The digestive tract is an organ system. The male reproductive system is quite different from the female system.