Why are earthworms classified as annelids?

Earthworms are classified as annelids due to their segmented body structure, which is a defining characteristic of the phylum Annelida. This segmentation allows for greater flexibility and mobility, as well as specialized functions in different body segments. Additionally, earthworms possess a coelom, or body cavity, which is also a trait of annelids. Their segmented bodies, along with features such as a closed circulatory system and a segmented nervous system, further solidify their classification within this phylum.