| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Achaeus cranchii Leach 1817 (Cranch's spider crab) | 0 | 0 | 1 |
| Achelia | 4 | 0 | 0 |
| Achelia echinata Hodge 1864 | 0 | 0 | 1 |
| Neritopsina | 0 | 0 | 1 |
| Achelia laevis Hodge 1864 | 0 | 0 | 1 |
| Ammothella longipes (Hodge 1864) | 0 | 0 | 2 |
| Acidostoma Lilljeborg 1865 | 2 | 0 | 0 |
| Acidostoma obesum (Spence Bate 1862) | 0 | 0 | 2 |
| Acidostoma obesum (Spence Bate 1862) | 0 | 0 | 2 |
| Acinetospora Bornet 1891 | 1 | 0 | 0 |
| Acinetospora crinita | 0 | 0 | 1 |
| Acinetosporaceae | 5 | 0 | 0 |
| Acipenser | 1 | 0 | 0 |
| Acipenser sturio Linnaeus 1758 (Atlantic Sturgeon) | 0 | 0 | 1 |
| Acipenseridae (sturgeons) | 1 | 0 | 0 |
