Blue jellyfish

Blue jellyfish

Blue jellyfish ©Linda Pitkin/2020VISION

Blue jellyfish

Scientific name: Cyanea lamarckii
Often confused with the larger but similarly shaped lion’s mane jellyfish, the blue jellyfish can be colourless when young and develop a striking blue-purple bell as it matures.

Species information


Bell: up to 30cm across

Conservation status


When to see

May to October


This beautiful jellyfish is often seen around the UK coastline in summer and autumn. They are attracted inshore by blooms of plankton that provide a plentiful supply of food. The blue jellyfish can drift along, easily capturing prey with its dense array of stinging tentacles.

Like many of the jellyfish species, this animal does sting, so if you find one on the beach it's best not to handle it.

How to identify

A typical looking jellyfish, with a dome-shaped bell and stinging tentacles trailing underneath. The bell colour depends on maturity and can vary from pale yellow to purple. Paler (younger) individuals are easily confused with the larger lion's mane jellyfish.


Recorded along all UK coastlines in summer months.

Did you know?

A group of jellyfish is known as a “smack”, but is more commonly referred to as a “bloom”.