Head of Marine at the Cumbria Wildlife Trust, Georgia de Jong Cleyndert, said although the “incredible” blue creatures looked like jellyfish, they were actually colonial hydrozoans.
She said: “Each by-the-wind sailor is made up of hundreds of tiny, specialised animals working together as a single floating colony.
“Although they are not jellyfish, they do have a very mild sting, even after they have washed up so do not touch them.”
The specialist said the species’ blue translucent sail allows them to drift huge distances across the surface of the sea.
“When conditions are right, particularly after periods of persistent onshore winds, thousands can be washed up along our shores,” she said.
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