It seems these open ocean drifters are slowly being blown up the Irish Sea, as this week five Portuguese Man-o-War (Physalia physalis) have been found washed up at Biggar Bank on Walney Island, Cumbria.

These jellyfish-like animals normally live in the open seas but strong and persistent south westerly winds and autumnal storms are causing them to be washed ashore. Sightings of Portuguese Man-o-War occur every few years in the UK but are rare this far north in the Irish Sea.

Senior Marine Conservation Officer for the Cumbria Wildlife Trust, Dr Emily Baxter says: “If they have washed up on Walney Island it is highly likely that they will also appear on other beaches across the North West.”

These beautiful creatures are not ‘true jellyfish’ but very close relatives of jellyfish, corals and anemones. They are siphonophores – a group of highly specialised clones called ‘zooids’ that all work together as one animal. They have a bright blue-purple float, shaped like a Cornish pasty, which floats on the sea surface and blue tentacles that hang below the surface, stretching over 10 metres in length.

Each of their zooids takes on a different form and function. Some are specialised for feeding, some for catching prey and even one for floating. They have thousands of stinging cells – little capsules loaded with tiny barbed harpoons – that deliver venom to paralyse and kill their prey (small fish and crustaceans). Though it is rarely fatal for humans, their sting can pack a painful punch, so look but don’t touch!

Emily says: “As the number and distribution of sightings has increased since early September we could see more washing up in the North West, so keep an eye out next time you are out on the shore. Although they are beautiful and fascinating, it is important to ensure children and dogs are kept away from any stranded Portuguese Man-o-War as they can still sting even when dead.”

These beautiful stingers play an important role in our ecosystem, providing shelter and protection for small fish. They are also food for the unusual swimming sea slug and violet sea snails.

With a changing climate and the prospect of more stormy weather, it is also likely that there will be an increase in the frequency of strandings of these open ocean drifters over the coming years.