Structure and Function: Earthworms have segmented skin and bilateral symmetry. They are worms and have worm parts and the inside of the worms have some organs but not that many because they are just worms. They have a closed circulatory system.
Ecology: Earthworms and many other annelids spend their lives burrowing through the soil,aerating it, and mixing it to the depths of more than two meters. Their tunnels provide passageways for plant roots and water and allow the growth of beneficial, oxygen-requiring soil bacteria. Earthworms pull plant matter down into the soil and pass it through the gut. The gut grinds the soil and partially digests it. Then, they mix it with the bacteria for a faster decomposition. Worms also mine minerals from deeper soil layers, bringing them to the surface.