They might be stranded on the beach you’re heading for and they can sting when dead.
Cheshire Wildlife Trust is encouraging people to keep their eyes open after five Portuguese man o’ war were found washed up on Walney Island in Cumbria.
That means there is ‘every chance’ they could be found along Wirral’s coastline as they slowly drift up the Irish Sea with this autumn seeing the highest number of strandings for years.
The beautiful jellyfish-like creatures have been washing up on beaches in the south west of England in their thousands.
But until now they have only been seen as far north as Pembrokeshire in Wales and Dublin in Ireland.
Mike Davis from Barrow went down to the beach in Cumbria just before sunset when he came across the Portuguese man o’war.
'We couldn't believe our eyes'
He said: “At first we just found one, it was about six inches long. Then as we continued to walk down the beach we found four smaller ones. I’m sure there must be more washed up. It was amazing, we couldn’t believe our eyes!”
The 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 said to be rare this far north in the Irish Sea.
Senior marine conservation officer for North West Living Seas Dr Emily Baxter said: “If they have washed up in Cumbria it is highly likely that they will also appear on other beaches across the north west.”
The beautiful creatures are not ‘true jellyfish’ but very close relatives of jellyfish, corals and anemones.
They are siphonophores, a group of highly specialised clones that all work together as one animal.
The creatures 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 10m in length.
Each of their clones takes on a different form and function with some 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 of small fish and crustaceans.
“Though it is rarely fatal for humans their sting can pack a painful punch, so look but don’t touch,” suggests the trust.
Dr Baxter added:”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.”
The beautiful stingers play an important role in the planet’s 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 suggested it is also likely that there will be an increase in the frequency of strandings of the open ocean drifters over the coming years.
To help track where they are washing up, tweet pictures of the stingers to @LivingSeasNW or report sightings to www.mcsuk.org/sightings .