#phylum classification
- Annelids — A major phylum of bilaterally symmetrical invertebrate animals (Annelida), comprising segmented worms such as earthworms, leeches, and marine polychaetes. Structurally, their body is characterized by homonomous metamerism, being divided externally and internally (by transverse septa) into a series of repeating ring-like segments, possessing a closed circulatory system and a ventral ganglionic nerve cord.