| Species name | Common name | Distribution | Max. Length (cm) |
|---|---|---|---|
| Hydra americana Hyman, 1929 |
White hydra | North America | |
| Hydra canadensis Rowan, 1930 |
Alberta hydra | North America | |
| Hydra cauliculata Hyman, 1938 |
North America | ||
| Hydra hymanae Hadley & Forrest, 1949 |
Jersey hydra | North America | |
| Hydra littoralis Hyman, 1931 |
Swiftwater hydra | North America | |
| Hydra minima Forrest, 1963 |
North America | ||
| Hydra oligactis Pallas, 1766 |
Brown hydra | North America | |
| Hydra oregona Griffin & Peters, 1939 |
Oregon hydra | North America | |
| Hydra pseudoligactis (Hyman, 1931) |
False brown hydra | North America | |
| Hydra rutgersensis Forrest, 1963 |
North America | ||
| Hydra utahensis Hyman, 1931 |
Utah hydra | North America |