| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Aaptoryctes | 1 | 0 | 0 |
| Aaptoryctes ivyi | 0 | 0 | 1 |
| Aaptos Gray 1867 | 1 | 0 | 0 |
| Aaptos aaptos (Schmidt 1864) | 0 | 0 | 1 |
| Aaptos angulospiculata | 0 | 0 | 1 |
| Aaptos bergmanni de Laubenfels 1950 | 0 | 0 | 1 |
| Aaptos spongia | 0 | 0 | 1 |
| Aaroniella | 1 | 0 | 0 |
| Aaroniella badonneli (Danks & L. 1950) | 0 | 0 | 1 |
| Aartsenia Warén 1991 | 1 | 0 | 0 |
| Aartsenia arctica (Dall & Bartsch 1909) | 0 | 0 | 2 |
| Aatocrinus | 1 | 0 | 0 |
| Aatocrinus permicus | 0 | 0 | 1 |
| Ababa | 1 | 0 | 0 |
| Ababa tantilla (Le Conte 1866) | 0 | 0 | 1 |
