They have already "claimed the scalp" of the Prime Minister while he was on holiday in Lanzarote. Now, a marauding army of jelly fish is set to invade the British coastline, scientists have warned.
The British Red Cross is warning beach-goers not to trust the old myth that fresh urine is the best treatment for jellyfish stings, as experts confirmed an impending influx of barrel jellyfish over the next few months due to warmer weather.
Jellyfish measuring up to 3.2ft in diameter are washing up on Britain's shores. As many as ten barrel jellyfish have appeared on beaches around the south coast in recent weeks.
Barrel jellyfish - Rhizostoma pulmo in Latin - are often known as dustbin-lid jellyfish because of their enormous size.
This one was spotted in the sand in Portland, Dorset, by wildlife photographer Steve Trewhella.
A sting from a jellyfish can be extremely painful, but trying to treat it with urine isn't going to make your day any better. Urine just doesn't have the right chemical make-up to solve the problem. Instead, a better source of treatment is even easier at hand: salty seawater. If people have been stung, they need to get out of the water to avoid getting stung again. Once out, slowly pouring seawater over the sting will help ease the pain.
Doing the same thing with vinegar can be even more effective as the acid helps neutralise the jellyfish sting. But, unless you're near a chip shop, seawater will probably be easier to find.
Forecasters expect high pressure to take hold later in May - sending temperatures soaring above 20C. In recent weeks, up to 10 barrel jellyfish have been spotted washed up on beaches around the South Coast.