If you had to pick a sea creature that you didn’t want to get into the water with, jellyfish might be up their in your top picks. In every one of the world’s oceans, these gelatinous invertebrates drift through the water with their tentacles stretching behind them like a bride’s veil.
But if you happen to touch these dangling appendages, you might be in for a nasty surprise. Jellyfish tentacles can deliver a venomous sting – and they can still hurt you when they're dead.
- What's the most common jellyfish in Britain?
- Guide to jellyfish: British species identification and how to treat stings
- This lethal predator is the most venomous in the ocean – and rising temperatures could drive them to the UK…
Does the UK have any deadly jellyfish in its waters?
Thankfully in the UK we don't have any deadly jellyfish but we do have a couple that could give you a nasty shock
Lion's mane jellyfish (Cyanea capillata)
For many years, the Lion’s mane jelly was thought to be the biggest jellyfish in the world because of an 1856 claim that a geologist caught one measuring 2.3 metres in diameter with 37-metre tentacles. Although many now believe this was an exaggeration, it’s still among the largest species of jelly.
Named for its bushy red tentacles (it has over a thousand of them), which resemble a lion’s mane, this huge jellyfish can inflict a painful sting. If you touch them, expect inflammation and welts to develop on your skin. As well as the pain and swelling, symptoms can include headaches, nausea and muscle pain.
Despite what Sir Arthur Conan Doyle might have us believe (in the 59th Sherlock Holmes story, The Adventure of the Lion's Mane, this jellyfish caused the death of a schoolteacher), fatalities from Lion’s mane stings are incredibly rare. If you do get on the wrong side of these trailing tentacles, it’s best to seek medical advice as soon as possible in case you have an allergic reaction.
Portuguese man of war
Although people often call the Portuguese man of war a jellyfish, it’s actually a siphonophore. It is made up of a colony of thousands of organisms that work together as if they were one animal – some are responsible for feeding, some for reproduction, some for defence and some make up the ‘sail’ on top which helps the Man o’War travel across the ocean.
Stings are very painful and often have similar symptoms to those of a jellyfish. It’s rare for its sting to kill a human but it has happened.
