Mass jellyfish strandings and huge numbers at sea are being spotted around Britain's coast as holidaymakers take to the beach and the water.
The lion's mane sting leaves red welts on skin
The hazardous lion's mane jellyfish is just one of those blooming in UK seas.
The Marine Conservation Society (MCS) wants people to report their jellyfish encounters, to further help research after a successful survey in 2003.
Research results will be used by marine biologists in studying the leatherback turtle - which eats the creatures.
The critically endangered giant visits UK waters to feed on its favourite jellyfish prey.
Scientists say people's feedback will complement research on climate and sea temperatures to understand the ecology of the leatherback.
"We have had 300 reports of hundreds of thousands of jellyfish," said Peter Richardson, MCS species policy officer.
"We're really interested in where they occur and an idea of numbers - in ones or twos, or washing up in their millions."
It is hoped the survey results will help conserve the threatened turtles. They are often killed by eating rubbish resembling jellyfish - like plastic bags - or when they become entangled in fishing nets and pot lines.
Drawing up a picture of their feeding habits and location will help experts target areas to promote conservation.
The MCS wants people to fill in the form on its website if they see the different species - from the stinging lion's mane to the harmless moon, attractive blue and compass, and massive barrel jellyfish.
The lion's mane is Britain's largest species, up to 2m wide, a big, round "typical jellyfish shape" and bright reddish-brown.
Critically endangered leatherbacks eat the jellyfish
It has a smooth bell-shape top and a red-brown frilly mass of tentacles, which can stretch for several metres.
One man stung in the Mersey Estuary in 2003 reported feeling as though he had been electrocuted throughout his body, Mr Richardson told BBC News Online.
He, and another swimmer off the coast of the Hebrides, suffered red welts on their skin and nausea.
The MCS has advice for anyone coming into contact with jellyfish.
"If you are swimming and find yourself amongst a swarm of them, that's a dangerous situation," said Mr Richardson.
Never touch with bare hands
Use a stick or wear arm length rubber gloves to turn them
Beware of stinging tentacles
Keep your face well clear
Seek medical advice if stung
"We don't want to panic people, there's a few records of people getting stung, but jellyfish aren't flying at people and attacking them.
"But people need to be aware that they can sting and it hurts," he said.
"Certain species we recommend you do not touch. For others, use long rubber gloves, a stick, and keep your face well clear."
"If you're badly stung, seek medical advice."
And, the MCS points out, there are worse things floating past in UK waters.
It wants to encourage people to keep seas clean and capable of sustaining life, by not dumping litter or flushing rubbish down the toilet.
"We are more of a threat to jellyfish and other marine life than they are to us," said Mr Richardson.
"If we get people to appreciate we have these spectacular turtles here, hopefully they will take on board it's not acceptable to leave litter."
Large numbers of Lion's mane jellyfish seen in the Mawdach estuary (visible from Barmouth bridge at high tide) at the beginning of June during hot weather. Some with diameter of approx 1m +. Lots of other species washed up on shore at Barmouth and Tal y Bont Gwynned.
Mark Yates, Runcorn, Cheshire
Lion's Manes can usually be found in large numbers off the coast of Scarborough during the summer months. Some years they are quite prolific to the point that we don't bathe.
Four years ago my son was stung on his inner thighs and to this day still feels pain if he stays in salty water for long periods. I've been stung once (a small area on the back of my hand) and can only describe the initial pain as excruciating.
Simon Graham, Scarborough, UK
In the last month I have seen hundreds of jellyfish along the walkways of the Ipswich docks. The jellyfish are translucent white in colour with 4 circles in the centre. They were still there this morning.
Whilst away for the weekend in Wales (weekend of 26/27th June), we went to Rhossilli Bay and there were hundreds of jellyfish stranded on the beach. I don't know what type they were but they were pink and transparent/translucent. I can honestly say I have never seen so many jellyfish in one place in all my life
Sara Hooper, Redditch, Worcestershire
I was surfing in Perranporth in May and saw some small blue/purple jellyfish. Some were in the water and a few were washed up. I've been in the water there many times before over the last few years but this is the first time I've seen anything like this.
We often come across jellyfish when diving in UK waters but not in swarms. Lionsmane, moon, compass and small comb jellies are the most common along with the occasional Portuguese man-o-war and by-the-wind-sailor. We've yet to see a turtle!
Martin Hunt, Manchester, UK
I was recently on holiday in the Dornoch area of NW Scotland(July 5th - 12th), in a small town called Embo, it is located on the Dornoch Firth, Moray Firth. I was very surprised to see large amounts of Jellyfish being washed up on the shore. Not sure of the numbers but it would in its hundreds everyday, approx 3-5 jellyfishes per square metre on the shoreline. I am not sure of their name but they vary in size to 5cm diameter to about 20cm, clear with 4 purple/blue circles on them. I am sorry I do not have a picture of them but I have been to many beaches all over Britain and never seen so many.
Alan Burns, Bishopbriggs
My wife and I saw our first jellyfish strandings of the year two days ago on the 7th July, 2004. There were five jellyfish, which I believe to be common jellyfish, stranded on Fenella Beach at Peel in the Isle of Man.
D.E. Brown, Higher Foxdale, Isle of Man
I frequently see jellyfish on my scuba diving trips. We are always equipped with antihistamine creams and pills during the season. They are beautiful underwater but can ruin your days diving.
Rosheen Dalgleish, Scotland
While camping in the Lake District at Millom the first week of June, we walked along the beach one day and there were a couple of hundred stranded jellyfish ranging from 150mm to 500mm diameter. That was over a distance of about 1 mile and they were all a brownish colour.
David White, Formby, Liverpool
Saw a few different coloured jellyfish washed up on the beach off the coast of Barra, Outer Hebrides, Scotland. They were approx 20 - 30 cm in diameter. Most were clear with either a distinctive blue colouring or red/brown colouring. When travelling back to Oban on the boat more clusters of jellyfish were spotted.
Carolann Mure, Carrickfergus, Northern Ireland
Onshore winds have brought thousands of aurelia aurita onto lunanbay shore over the past 3/4 weeks. I will try to be more accurate in future now I know some one is counting.
Burnie Maurins, Arbroath Scotland
On Friday evening 3rd July 2004 there were thousands (to many to count) washed up on the beach at Broughty Ferry, Dundee.
Richard Dye, Broughty Ferry, Dundee