| Features | Sipunculids | Annelid |
| 1. External segmentation | In Sipunculids species there are no External segmentation | Most of an annelid's body consists of segments, that are partially identical, having the same sets of internal organs and external chaetae and in some species appendages. |
| 2. Repetition of internal organs | The internal organs of sipunculids are not repeated like annelid | The internal organ of the Annelid are repeated. |
| 3. Septa between segmentation | Septa between segments are seen in most sipunculid species. | There are no septa between two segment in any species. |
| 4. Cuticle materiel | Sipunculids have a body wall somewhat similar to that of annelids in that it consists of a non-ciliated epidermis overlaid by a cuticle an outer layer of cuticular and an inner layer of longitudinal musculature | Annelid's cuticle are made of collagen fibres usually in layers that spiral in alternating directions so that the fibres cross each other. |
| 5. Moulting | Sipunculid doesn't have any moulting of their any body part structure. | Annelids moult their jaws, and leeches moult their skin. |
| 6. Body Cavity | Coelom is the main body cavity of the sipunculids In sipunculids there are two coelom main and proboscis. | Coelom is the main body cavity of the annelid, but this is reduced or missing in many leeches and some small poly-chaetae |
| 7. Circulatory system | Circulatory system open outflow, return via branched vein. | Circulatory systems are closed in most species. |
- 56 reads