Sea Nettles Factsheet

Article | Updated 5 years ago

Chrysaora kynthia

The sea nettle is bluish-white with colourless warts over the surface. It has a flattened dome-shaped bell that is up to 12 cm in diameter. It has frilly, long, central mouth arms, and 24 very long tentacles (see figure).
Jellies drift with the currents and swim with a pumping action of their bell. They have a central mouth surrounded by the mouth arms. They have a minute polyp stage that attaches to rocks and buds off the tiny jellies which then grow to maturity.
Sea nettles have been reported from Dawesville, Cockburn Sound, Fremantle and Perth in summer.
Their sting is extremely painful but not life threatening.
A sudden burning sting that may persist for many hours. Raised red weals may occur, the redness may spread, and should disappear in 2 to 3 days.
Do not swim in areas where they have been seen. Wear protective clothing such as a lycra top, skivvy or stinger suit.
First Aid
  1. Do not treat with vinegar.
  2. Remove any tentacles from the skin using tweezers or a gloved hand.
  3. Neutralise sting with a paste of bicarbonate of soda and seawater, if unavailable wash the area with seawater.
  4. 4 Apply cold pack, and possibly a pain relieving cream, to the affected area for pain relief. This may need to be repeated for some weeks if the itchiness persists.
Loisette M. Marsh & Shirley M. Slack-Smith (2010). Field Guide to Sea Stingers and other venomous and poisonous marine invertebrates of Western Australia. Western Australian Museum. Perth, Western Australia.
A sea jelly swimming upwards to the surface

An individual of Chrysaora kynthia showing the flattened bell, the frilly, central mouth arms and the very long tentacles
Photo by Sue Morrison, copyright WA Museum