Lion's mane jellyfish

The lion's mane jellyfish may look like an ethereal beauty in the water but don't be fooled, the traditional red colouring of the jellyfish is a warning of its painful sting.

What do they look like?

Spot them by their large reddish-brown, umbrella shaped bell, and from their mass of short, thick, folded arms as well as long hair-like tentacles.

Where can they be found?

North UK seas – May to October. Found in the cold waters of Arctic, North Atlantic, and North Pacific seas, but have been seasonally seen in warmer southern waters.

Did you know... The largest one recorded had tentacles 36.6 metres long! They’re a favourite food for the leatherback turtle.

Key facts

Always an exciting find for beach combers, the lion’s mane jellyfish lives up to its name, with fantastic deep-red, fiery tentacles. Be careful though – even beached they can deliver a painful sting.

IUCN status	Not Evaluated
Sting strength	Lion's mane jellyfish have one of the most painful stings of UK jellyfish which causes intense pain almost immediately after being stung. Be very careful if you find yourself near a lion's mane jellyfish both in the water or when it is beached as they can still sting after death.
Length	Typically 50cm but can reach 2 metres in diameter.
Weight	Varies greatly, but have been recorded to reach over 1,000 KG!
Habitat	Open, cooler seas
Diet	Jellyfish often prey on other jellyfish, with the lion’s mane’s diet including the smaller moon jellyfish. They also eat small fish, tiny crustaceans, zooplankton, fish larvae and eggs. To catch their food, they use specialised "harpoon-like" stinging cells (nematocysts) that shoot out and inject venom when touched, to hold and immobilise their prey.
Age lifespan	Jellyfish generally don’t have very long lifespans, but while some species only live a few hours, the lion’s mane is comparatively long at a few years.
Speed and distance	Like many species of jellyfish, lion's mane are not strong enough to swim easily against the water current, so often turn up on beaches at lower tides. However, they can move slowly through the water by contracting and relaxing their "bell", which helps propel them.