The thimble jellyfish Linuche unguiculata. *Photo by Rachel Parsons, BIOS
The thimble jellyfish Linuche unguiculata. *Photo by Rachel Parsons, BIOS
WEDNESDAY, AUGUST 3: Tiny ‘thimble jellyfish’ are believed to be responsible for reports of several swimmers developing a rash over the holiday weekend.

Authorities are advising anyone who is concerned about the outbreak not to swim in the Great Sound.

The rash, sometimes referred to as ‘swimmers itch’ or ‘sea lice’ can cause swimmers to develop itchy skin and a red rash.

A Conservation Services spokesman said:

“While investigation into the exact cause of stinging and rash is underway, initial thoughts are that this is likely to be a result of the thimble jellyfish Linuche unguiculata.

“Local scientists took water samples yesterday but were unable to positively identify several small jellies that were less than 1mm in size as they were at an early developmental stage with insufficient diagnostic features. Adult Linuche are up to 2 cm in size.

“However, scientific evidence from other jurisdictions indicates that all floating stages of this species can produce sea bather’s eruption.

“Despite not positively identifying the species as Linuche, the assumption is that the small jellies found in the samples are responsible for the swimmers’ reactions. Further samples will be taken during the next few days in an effort to positively identify the species.

“If the thimble jellyfish are responsible, most of the stings occur when the animals are trapped against the skin, often around the edges of swimwear, rather than just brushing against them while swimming.

“Stinging cells may also be triggered by fresh water so swimwear should be removed before showering.

“Treatment may not be necessary and if left alone the rash should go away within a few days. Calamine lotion may reduce the irritation. If symptoms persist for longer than several days, or worsen, a Doctor should be consulted.

“Jellies may still be present in swimwear after exiting the ocean and it is recommended that swimming attire be machine washed to avoid the possibility of further stinging when swimwear is used again.

“Out of an abundance of caution, swimmers are being advised to avoid swimming in the Great Sound and adjacent areas as this is the area where most people were affected during the Cup Match holiday.

“The South shore is less likely to have the same density of jellies due to the larger dilution effect. Jellies are also likely to thrive in inshore waters because there is more food for them. The duration of this event may stretch over 2-3 weeks.”