The lion’s mane jellyfish is a giant jellyfish of cold northern seas, with a reddish bell and a huge mass of trailing tentacles. It is the largest known jellyfish on Earth.
Interesting facts
- It is the largest known jellyfish in the world.
- Its hundreds of tentacles hang in clusters, like a lion’s mane.
- Its sting is painful but rarely dangerous.
- In 2010, a single dead lion’s mane broken into pieces stung about 150 swimmers in New Hampshire.
- Young fish shelter among its tentacles, protected from predators.
- It features in a Sherlock Holmes story, ‘The Adventure of the Lion’s Mane’.
Behaviour
Lion’s mane jellyfish drift near the surface, trailing their tentacles like a net to catch prey.
Breeding and young
Adults release eggs and sperm; larvae settle as polyps on the seabed, which produce young jellyfish in spring.
Threats and conservation
Not threatened.
Where to see it
- Coasts of Britain and Norway in summer
- Gulf of Maine, USA
- Alaska and British Columbia
- Public aquariums
Status source: IUCN Red List. Profile last reviewed September 2026.
