Jellyfish are commonly seen washed up on the beaches during the summer months, but fortunately in Wales, most are relatively harmless and stings can be easily treated. The sting is caused by specialized cells called nematocysts, which are triggered by contact, and inject venom into the victim. If stung, the current advice is to remove any remaining stinging cells with tweezers, or gently scrape the affected area with a straight edge (e.g. a credit card). It is now thought that the old treatment of applying vinegar (even if you had some) is ineffective. In the unlikely event of suffering an allergic reaction, get to hospital quickly!
Jellyfish typically have a lifespan of just a few months, and are made up of around 90% water.