- Kingdom: Animalia
- Phylum: Cnidaria
- Class: Hydrozoa
- Subclass: Hydroidolina
- Order: Leptothecata
- Family: Laodiceidae
- Scientific name: Staurophora mertensii
- Norwegian: korsmanet
Characteristics:
Hydroid stage: The hydranths are approximately 1 mm and hardly visible for scuba divers.
Medusa stage: The bell is large, the diameter may reach 30 cm. The shape is flattened, the height is approximately 1/8 of the diameter. The stomach, mouth and four radial canals form a large cross, nearly reaching the umbrella margin. There are a large number of marginal tentacles.
Habitat:
The hydroid is probably coastal. The medusa has been found on all depths, from the surface and down to a depth of 150 meters.
Distribution:
This species is considered bipolar, existing both in the Arctic as well as Antarctic. In the North Atlantic ocean it can be found as far south as the North Sea.