Invertebrates
Barrel Jellyfish
Rhizostoma pulmo · also called dustbin-lid jellyfish
Off a Cornish beach in July, a barrel jellyfish pulses slowly through the shallows, a bell the size of a dustbin lid with a shoal of small fish sheltering beneath.
Overview
The barrel jellyfish, Rhizostoma pulmo, is a large, dome-shaped jellyfish of coastal seas around the north-eastern Atlantic, the North Sea, and the Mediterranean. Its size, lack of marginal tentacles, and role as shelter for young fish make it one of the most imposing jellyfish seen around Britain.
A jellyfish that shelters fish
Young whiting and horse mackerel often live in the shadow of a barrel jellyfish, using it as moving shelter from the larger fish that hunt them.
Status
Not Evaluated, but widespread and often abundant.
Barrel Jellyfish: common questions
Does the barrel jellyfish sting?
Its sting is mild for most people, though it can irritate sensitive skin, and it is much weaker than that of a lion's mane jellyfish.
Why does it have no tentacles?
It has no long tentacles around the edge of its bell, but eight thick, frilly oral arms hang underneath, covered in many small mouths.
Do fish live with barrel jellyfish?
Yes, young fish such as whiting and horse mackerel often shelter under the bell and among the arms.
Where is the barrel jellyfish found?
It lives in coastal and shelf seas of the north-eastern Atlantic, the North Sea, and the Mediterranean.