After a cold spring, warm summer weather ups U.K. jellyfish numbers Lion's Mane jellyfish. Credit: Dan Hershman, Wikipedia, Creative Commons LONDON, July 30 (UPI) -- Britain's coastal areas have seen a rapid rise in jellyfish blooms in an ongoing spell of warm weather, a conservation group says. After a long, cold spring that saw very few reports of jellyfish before June, several species are now being seen in rapidly growing numbers, the Marine Conservation Society reported as part of its national jellyfish survey. One species, the Lion's Mane, is capable of inflicting a powerful sting and scientists are warning people not to touch them. "They're our biggest jellyfish, they grow to about two meters (6 feet) wide and have meters of trailing tentacles, and they have very powerful stings," said Peter Richardson, the society's biodiversity program manager. The society has been releasing a jellyfish survey annually for 10 years based on reports from members of the public. "We ask people to report what they see online and send us photos," Richardson told the BBC. "But always look and don't touch, as [jellyfish] can sting and that could really spoil your day," he said.