New research from NUI Galway and the University of Hawaii at Manoa has identified the best way to treat a sting from the lions mane jellyfish (Cyanea capillata). The lions mane jellyfish is the most problematic jellyfish in Ireland and the UK with 1000s of bathers being badly stung each year. With over a 1,000 tentacles that can stretch up to four or five metres in length, a bad sting from a lions mane jellyfish can cause severe local reactions and extreme pain.