| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Acoela (acoel flatworms) | 1 | 0 | 0 |
| Acoetidae | 1 | 0 | 0 |
| Acontiophorus Brady 1880 | 1 | 0 | 0 |
| Acontiophorus scutatus (Brady & Robertson 1873) | 0 | 0 | 1 |
| Acrenhydrosoma Lang 1944 | 2 | 0 | 0 |
| Acrenhydrosoma perplexum (Scott T. 1899) | 0 | 0 | 2 |
| Acrenhydrosoma perplexum (Scott T. 1899) | 0 | 0 | 2 |
| Acrilloscala Sacco 1890 | 1 | 0 | 0 |
| Acrilloscala geniculata (Brocchi 1814) | 0 | 0 | 1 |
| Acrochaete | 2 | 0 | 0 |
| Ulvella parasitica | 0 | 0 | 2 |
| Ulvella repens | 0 | 0 | 2 |
| Ulvella wittrockii | 0 | 0 | 2 |
| Acrochaetiaceae | 4 | 0 | 0 |
| Acrochaetiales | 1 | 0 | 0 |
