2. Head not distinct but proboscis is elongated and prominent.
3. They have distinct metameric segmentation visible externally and the segments 45-48.
4. The setae are present only ventral sides in bundles.
5. They have three posterior gills and clitellum.
6. Male gonopore is present on the segment next to the one in which testes are present.
7. They reproduce asexually by transverse fission or through zooids in chain.
8. They are carnivorous and nermaphrodite Development is direct.