| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Astomonema Ott, Rieger, Rieger & Enderes 1982 | 0 | 0 | 1 |
| Astropecten Gray 1840 | 0 | 0 | 2 |
| Atlasaster Lambert 1931 | 0 | 0 | 1 |
| Balanoglossus delle Chiaje 1829 | 0 | 0 | 2 |
| Bathynoe cascadiensis Ruff 1991 | 0 | 0 | 2 |
| Bathynoe tuberculata (Treadwell 1906) | 0 | 0 | 2 |
| Bayerpolynoe floridensis Pettibone 1991 | 0 | 0 | 3 |
| Bdelloidea (Bdelloida) | 0 | 0 | 3 |
| Bdelloura | 0 | 0 | 3 |
| Benhamipolynoe antipathicola (Benham 1927) | 0 | 0 | 2 |
| Benhamipolynoe cairnsi Pettibone 1989 | 0 | 0 | 2 |
| Benthoscolex cubanus Hartman 1942 | 0 | 0 | 7 |
| Bhawania heteroseta Perkins 1985 | 0 | 0 | 5 |
| Bithyniidae | 0 | 0 | 1 |
| Blanfordia A. Adams 1863 | 0 | 0 | 3 |
