This video says about itself:
Swimming with a giant Barrel Jellyfish
23 June 2014
This Barrel Jellyfish (Rhizostoma pullmo) was filmed in the Percuil Estuary, near St Mawes, Cornwall. Large numbers of these, the UK’s largest jellyfish species have been seen this year around our coast. They are totally harmless and feed on plankton. They do have stinging cells but they are not able to get through human skin. They can grow to 80cm wide and weigh up to 30 kilos!
From the Dorset Echo in England today:
Warmer weather sees return of the barrel jellyfish to Dorset shores
by Tara Cox, Reporter
APRIL has seen the return of the barrel jellyfish in Dorset due to warmer weather – and experts warn there could be more sightings to come.
Barrel jellyfish, which can grow up to one metre wide, have been spotted in Weymouth Bay and Lyme Bay in recent weeks.
And the Dorset Wildlife Trust claim that during the spring and summer, we could expect to see up to eight different species of jellyfish along the Dorset coast.
Last year, more and more sightings of the sea creatures were reported after members of the public spotted them both in the ocean and washed up on beaches in Weymouth, Portland and West Dorset.
Barrel jellyfish can grow up to one metre wide.
These particular jellyfish do not sting, but the trust is advising members of the public not to touch any jellyfish they find washed up and to report them to the trust to identify and record.
Emma Rance, DWT marine conservation officer, said: “These oceanic drifters can change in shape, colour and size when they are beached.
“We would encourage people to look but not touch and keep their animals away from the jellyfish, because many jellyfish can still sting when dead.
“It’s very likely that we’re going to get more reports of jellyfish due to warmer weather. Barrel jellyfish feed on zooplankton – tiny animals floating in the water – which have increased due to longer days with more sunlight.”
The trust also said that the leatherback turtle and oceanic sunfish feed on jellyfish, so there could also be a possibility of seeing both of these species in Dorset.
Steve Trewhella, a professional wildlife photographer and environmental campaigner, said he was surprised to hear of jellyfish sightings on Portland and Chesil Beach as early as this in the year.
Broadwindsor resident and freelance writer Sophia Moseley spotted a barrel jellyfish on Lyme Regis beach near the iconic Cobb last Friday.
She said: “I took my two children down to the beach for fish and chips and was quite surprised to see it so early in the year.
“The jellyfish was 20 inches in diameter. It’s a worry that they are populating our seashore but there isn’t much we can do about it.”
Sophia tweeted a picture of the jellyfish to the Dorset Wildlife Trust, and said she would encourage others to do the same.
People who see a jellyfish are encouraged to take a photo and report it to the DWT via their Facebook page at facebook.com/dorsetwildlife.
Alternatively, any sighting photos can be tweeted to @DorsetWildlife.
New science: Injured jellyfish seek to regain symmetry: here.