Portuguese man o’war: Increase in sightings of jellyfish-like creature along Britain's coastline

There has been an increase in sightings of a jellyfish-like creature which can cause whip-like wounds from its stings along Britain's coastline.

Members of the public reported a total of 1,315 jellyfish sightings to the Marine Conservation Society for its annual survey of marine wildlife, including a 2% increase in sightings of the Portuguese man o'war.

The tentacles of the man o’war are covered in venom-filled capsules which are used to paralyse and kill fish and other small creatures.

But while excruciatingly painful for humans, a man o'war sting is not usually deadly.

A spokeswoman for the charity said the increase in the man o'war sightings was due to storms in October 2021 and February 2022.

“Although they have a bad reputation, these jellyfish-like creatures don’t normally occur in UK waters, preferring instead to drift in the open ocean," the spokeswoman said.

“Sightings of these unusual visitors were primarily along the south-west coast and the west coast of Scotland, with westerly winds carrying them across the Atlantic to our shores."

The MCS regularly records sightings of eight jellyfish species, with the compass jellyfish and the moon jellyfish, each accounting for 23% of sightings, seen in smacks – the collective noun for jellyfish – of more than 100.

The spokeswoman said 11 other species were spotted and added the charity saw an increase in ‘other’ species reported, up from 5% to 9% this year.

“Among these were the bioluminescent crystal jellyfish, which made up 3% of total sightings, and sea gooseberries at 1% – the highest percentages reported to date," she said.

“Tracking reports of ‘other’ species like these could show how changes in temperatures might be impacting jellyfish diversity in the UK.

“Crystal jellyfish are usually found in the Pacific Ocean, rarely spotted in UK waters, suggesting that warmer temperatures may be impacting jellyfish diversity in the UK.”

A total of 11 turtles, which feed on jellyfish, were reported, six of which were live leatherback turtles spotted on the coast of Scotland.

Amy Pilsbury, MCS citizen science project lead, said: “We use these sightings, alongside scientists, to spot trends in the distribution of jellyfish and marine turtles around the UK.

“Investigating the relationships between species can help us to discover more about our amazing underwater world and how it might be changing in response to things like climate change.”

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