| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Amathillopsis Heller 1875 | 1 | 0 | 0 |
| Amathillopsis spinigera Heller 1875 | 0 | 0 | 1 |
| Ammosphaeroidinidae | 1 | 0 | 0 |
| Ammotium Loeblich & Tappan 1953 | 1 | 0 | 0 |
| Ammotium cassis (Parker 1870) | 0 | 0 | 1 |
| Ampelisca Krøyer 1842 | 1 | 0 | 0 |
| Ampelisca macrocephala Liljeborg 1852 | 0 | 0 | 1 |
| Ampeliscidae Krøyer 1842 | 1 | 0 | 0 |
| Ampharete Malmgren 1866 | 3 | 0 | 0 |
| Ampharete arctica Malmgren 1866 | 0 | 0 | 1 |
| Ampharete borealis (M. Sars 1856) | 0 | 0 | 1 |
| Ampharete grubei | 0 | 0 | 1 |
| Ampharetidae | 4 | 0 | 0 |
| Amphidinium Claperède & Lachmann 1859 | 4 | 0 | 0 |
| Amphidinium crassum | 0 | 0 | 1 |
