Klasse: Hydrozoans (Hydrozoa)
| Year | Arter/grupper | Localities | Participants | Observations |
|---|---|---|---|---|
| 2014 | 2 | 2 | 2 | 2 |
| 2013 | 1 | 1 | 1 | 1 |
| 2002 | 2 | 2 | 2 | 3 |
| 2001 | 4 | 3 | 3 | 24 |
| 2000 | 1 | 1 | 1 | 2 |
| 1996 | 1 | 1 | 2 | 2 |
| 1994 | 1 | 2 | 2 | 2 |
| 1993 | 1 | 1 | 1 | 4 |
| 1992 | 1 | 1 | 1 | 1 |
| 1991 | 1 | 1 | 1 | 1 |
| 1990 | 1 | 1 | 1 | 1 |
| 1989 | 1 | 11 | 11 | 11 |
| Totalt alle år | 8 | 25 | 26 | 54 |