'I've never seen so many' - jellyfish invade North Wales beaches in their thousands

North Wales Live

6 hours ago

A huge invasion of 'pretty' jellyfish on the west Wales coast has left residents and tourist stunned. At this time of year beaches are often littered with the creatures but the sheer numbers being seen are beyond anything in recent memory.
A boat owner reported seeing 'millions' of jellyfish in Cardigan Bay and rough seas last weekend may have brought many closer to shorelines. With the UK currently gripped by a marine heatware, caused by the mild spring, warmer sea surface temperatures were expected to trigger a surge in jellyfish populations.
Online reports suggest large numbers on Gwynedd's beaches, including Criccieth, Fairboroune and Traeth y Greigddu (Black Rock Sands), near Porthmadog. Some of the most impressive invasions were seen at Barmouth, where one long-time local reported: 'There are thousands of them along the shoreline, I've never seen so many. They are about the size of a hand and have 4 purple rings visible in them.'
These are Moon jellies, the most common jellyfish in UK seas. Their most distinctive feature are the four circles visible through a translucent bell – these are actually their gonads, their reproductive organs.
In recent years, Spain has witnessed similar jelly surges and, ahead of this year's peak summer season, tourists have been warned to expect to see more washing up on popular beaches. In recent years, swimming bans have been implemented, blamed on climate change and rising sea temperatures.
Last summer, nearly 7,500 swimmers needed medical treatment for jellyfish stings on the Catalan coast, 41% up from the previous year. The good news for Welsh beachgoers is that Moon jellyfish are mostly harmless – their stings pose little risk to humans. 'We used to go swimming amongst them lol,' said one local. Join the North Wales Live Whatsapp community now
Neither are they a major threat to dogs, though they are slightly more vulnerable: potential symptoms can include itching, drooling and minor agitation. They may also lick paws or rub their face. In some cases, vomiting is possible if dogs lick or eat Moon jellies. More severe reactions are rare, though it's something to be aware of.
Other jellyfish have been reported around the coasts of Anglesey and Gwynedd in the past week, including Blue, Compass and Crystal jellies. At worst, all these give a mild irritating sting like a nettle rash. Larger, harmless Barrel jellies are also washing up.
When seen, a frequent comment is how beautiful they look. On finding a Moon jellyfish, one woman said online: 'I've seen these on Black Rock Sands they are so pretty with their purple rings.'
At Anglesey Sea Zoo, Brynsiencyn, a large number Moon jellies can be viewed in a tank: as many visitors attest, watching clouds of them gently undulate can be utterly mesmerising. 'They have short, delicate tentacles that hang down from the sides of the bell,' said the zoo.
'They catch their plankton prey using a layer of mucus over their bells - before passing the microscopic meals into their mouths parts using special tentacles.' Sign up for the North Wales Live newsletter sent twice daily to your inbox
The ones seen at Barmouth were small, likely juveniles: adults reach the size of a dinner plate and these have been spotted off Aberdyfi. 'There were some huge ones floating past in the sea, bigger than a football,' said one crabber.
More dangerous jellies, such as the Lion's Mane and Portuguese Man o' War, typically arrive in smaller numbers later in the summer. Beside the colour and interest jellyfish add to beaches, they help sustain marine and shoreline ecosystems by providing a meal for other creatures such as turtles, gulls and crustaceans.
Their arrival on beaches is often said to be a sign of warmer weather ahead - large numbers were reported in west Wales during the long hot summer of 1976. But don't get too excited: while the Met Office said there is 'potential for some warm or hot weather to develop' later this week, there will still be plenty of the wet stuff around.