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.
2. Describe how earthworms reproduce. Critical Thinking 1. The shape of the earthworm allows it to move easily through the soil. Why? 2. Why might it be advantageous for the earthworm to have setae located on the ventral surface rather than the dorsal surface? 3. The digestive system of an earthworm is sometimes described by biologists as a âtube