How do earthworms play a role in the ecosystem?

earth worms and other members of PHYLUM ANNELIDA are different from other worms in that they are SEGMENTED meaning that internaly, earthworms separated into segments by a thin membrane called the SEPTUM. Earth worms are also known for their barrel shaped CLITELLUM -----------=----

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that usulally covers segments 32-37. one more thing... earth worms have a CLOSED circulatory system, while most other worms have OPEN circulatory systems. hope this helps