| The oligochaetes include earthworms and a group of related, mostly freshwater, species of annelids. |
| In echiurans, sipunculans and in most polychaete annelids at least portions of the coelomic lining form the somatic and visceral musculature. |
| Morphology places sipunculans with annelids and molluscs, and their mitochondrial genes relate them to annelids. |
| Silurian ramphoprionid polychaete annelids, represented by their jaws, are described from extensive collections from Gotland, Sweden. |
| Many annelids and molluscs share patterns of development in early embryonic stages. |
| Arthropods, chordates and annelids are the three segmented phyla in the animal kingdom. |
