What are annelids?

Annelids have cylindrical bodies which are divided into many segments along the anterior and posterior axis. The number of segments varies from species to species. Not only are the features and appearance of the body segments similar, but the nervous system structure, circulation and excretory organs are all arranged repetitively, segment by segment, down the body. Common species in this group include earthworms and leaches. Although there are at least six other phyla, members of which are called worms, the annelids are the most common.