- Kingdom: Animalia
- Phylum: Cnidaria
- Class: Scyphozoa
- Order: Semaeostomaeida
- Family: Cyaniidae
- Scientific name: Cyanea capillata
- Norwegian: rød brennmanet
The Lion's mane jellyfish is vivid yellow, orange or sometimes even red. The flattened umbrella may reach a diameter of 2 metres. Swimmers should be aware. It is very unpleasant to get tangled in the sometimes 30 metres long tentacles. As most other jellyfishes, they reproduce in spring and die in the winter. Some survive the winter as larvae.
The medusa is seen in the summer or early fall. In southern areas small medusae appear in April, mature specimens are most frequent from June to September. In the northern regions, mature specimens have a peak abundance in August and September. The lion's mane jellyfish keeps near the surface, it is rarely seen deeper than 20 metres.
Possible cosmopolitan, but most frequent on the northern hemisphere.