Klasse: Hydrozoans (Hydrozoa)
| Species | Lenke til artsinfo | Reg. date | Obs. date | Location |
|---|---|---|---|---|
| Hydrozoans (Hydrozoa indet.) | 1993-12-08 | 1993-12-08 | Helgeroafjorden (Vestfold, Norway) | |
| Hydroider (Hydroidea indet.) | 2001-01-24 | 2001-01-24 | Espegrend (Vestland, Norway) | |
| Hydroider (Hydroidea indet.) | 2001-01-24 | 2001-01-24 | Espegrend (Vestland, Norway) | |
| Hydra sp. | 1992-06-12 | 1992-06-12 | Harestuvannet (Akershus, Norway) |
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