Although technically not a jellyfish the Blue Bottle, also known as the Portugese Man of War, does sting like one even when dead.

The creature's float ranges in size between two and 12cm, but the tentacles can be up to 10 metres long.

Port Elliot resident and regular beachgoer Howard McBeth said he had noticed enormous numbers of two similar kinds of jellyfish, Blue Bottles and By-the-Wind Sailors, on beaches since January 20.

"The most likely cause is prevailing onshore winds, over about a 10-day period, blowing them on to the beach," he said.

"It was difficult to avoid stepping on them on Middleton Beach a few days ago, but the numbers are decreasing now as the winds change."

Mr McBeth said a large number of distinctive blue Janthina shells had also been washing up along the coast recently.

There have been no reported fatalities from Blue Bottle stings in Australia, but they are painful and may cause an allergic reaction in some people.

According to recent studies, the most effective treatment is immersion of the stung area in hot water for at least 20 minutes.

ClimateWatch reports that between 10,000 and 30,000 Blue Bottle stings are recorded along the east coast of Australia each year, but only around 500 stings are reported in South Australia and Western Australia combined.

Several Gold Coast beaches were closed last week after 700 swimmers were stung by Blue Bottles in two days.