Blue jellyfish
Cyanea lamarckii
IUCN Status:Not Evaluated
The blue jellyfish is a small, strikingly coloured jellyfish, with a bright blue bell and long, frilly tentacles that deliver only a mild sting. They drift with the currents feeding on tiny plankton. They’re most common in late spring and summer, especially after spells of calm weather, and often appear alongside other seasonal visitors like moon and compass jellyfish.
What do they look like?
They're called blue jellyfish for a reason - purplish-blue lines radiate visibly through their bell-shaped body.
Where can they be found?
Found all around the UK, especially in summer
Did you know... A blue jellyfish’s age can be identified by the colour of their bell. When young, they are pale, but as they age, the bell becomes bright purple-blue.
Key facts
The blue jellyfish has a relatively mild sting - though this can still be painful.
While it appears quite similar to the lion’s mane (but much smaller), it has only recently been classed as a different species, though they are still related.
| IUCN status | Not Evaluated |
|---|---|
| Sting strength | Blue jellyfish have a mild sting. It is similar in strength to a stinging nettle. It can cause mild discomfort and be itchy. It is therefore best to avoid touching a blue jellyfish even after it has died. |
| Length | Up to 30cm (across the bell) |
| Weight | Lacking data |
| Speed and distance | Like many species of jellyfish, they're not strong swimmers and move slowly through the water with a pulsating movement. This also means they're susceptible to being moved by tides and currents. |
| Habitat | Open ocean |
| Diet | They live off a diet of phytoplankton or zooplankton, as well as the eggs and larvae of other aquatic animals, such as fish if they're caught in their tentacles. Like most jellyfish, they use tiny "harpoon-like" stinging cells (Nematocysts) in their tentacles, that shoot out when touched to grab hold of prey and inject them with venom. |
| Age lifespan | Like most jellyfish, they do not have long lifespans, usually less than one year |
