Climate crisis brings growing numbers of unusual jellyfish to UK seas

Among species whose numbers were on the rise was the portuguese man o’ war, a jellyfish-like creature that can deliver a fatal sting. Photograph: Cornwall Wildlife Trust/PA

Britain’s seas are becoming populated with large groups of unusual jellyfish owing to climate breakdown, a survey by the Marine Conservation Society (MCS) has found.

In its first marine sightings report, which builds on 20 years of citizen science, the society has found an increased abundance of jellyfish types, including those normally found in warmer climes. Thousands of volunteers take part in the MCS report, telling the conservation group which species of jellyfish and turtles they have seen.