Bathers at Sandycove in south Dublin have been advised to swim with extra caution after Lion's Mane jelly fish were spotted in the bay on Thursday afternoon.
Warning signs have been erected at the lifeguard patrolled Sandycove swimming area and red warning flags have been installed. While bathing has not been prohibited, lifeguards are “actively keeping a vigilant eye on the water and bathers”, a statement from Dun Laoghaire-Rathdown County Council said.
The council called for bathers to exercise caution and warned that Lion’s Mane can still deliver a sting when washed up on a beach.
“These species of jellyfish can deliver a venomous sting and may cause medical complications,” said the council.
The Lion’s Mane jellyfish is the most venomous of our indigenous species and one of the largest jellyfish in the world. It can grow to more than 2m wide with tentacles that can reach up to 60m in length.
The jellyfish have hundreds of long, hair-like tentacles and can give bathers a very severe sting which can lead to Irukandji-like syndrome. This syndrome, named after a type of box jellyfish, can include symptoms ranging from severe headache and backache to abdominal pain, nausea, vomiting, and even cardiac arrest.
The Lion's Mane jellyfish has become more geographically spread than its normal Irish Sea habitat, with sightings in the Celtic Sea and Atlantic waters last summer. Sightings were confirmed in 2018 off Galway's Blackrock swimming tower, Barna, Rinville near Oranmore, Traught near Kinvara and Newquay in Co Clare.
Any person who is stung and suffers symptoms including nausea, vomiting or respiratory distress should seek medical attention immediately, said the council.
