Bluebottles the size of a fist wash up on Gold Coast beaches

A large bluebottle that washed ashore on the Gold Coast. (Supplied: Coolangatta Community Facebook Page)

Bluebottles up to three times the usual size are washing ashore on the Gold Coast.

Scientists say little is known about the larger species' venom potency.

Lifeguards have reported relatively few stings: 20 across 39 patrolled beaches during the school holidays.

Bluebottles up to three times larger than those typically seen in Queensland waters are washing ashore on the Gold Coast, but scientists say little is known about the potency of their venom.

Griffith University marine ecologist Kylie Pitt said Physalia megalista was one of the biggest of five bluebottle species found in Australian waters.

"It doesn't turn up on the Gold Coast beaches all that often. They're usually further south," she said.

"But we don't have a lot of data about when and where they turn up."

Professor Pitt estimated the species' float or sail, which sits on the water's surface, was about 10 centimetres in length, while its stinger could stretch several metres.

Residents have been shocked by the large size of the bluebottles. (Supplied: Alan Spears)

"It is quite likely that the different species have got slightly different venom," she said.

"In terms of the way people react, it is dependent on the dose they get and the dose depends on the amount of tentacle that's attached to the skin."

Gold Coast City Council lifeguard supervisor Scott Franzmann said despite the busy school holidays, the impact had been relatively minor, with 20 stings reported across 39 patrolled beaches.

"It's a little bit early for bluebottles at this stage," he said.

"We don't get them until about December, January, around that Christmas period."

Tera Jesperson noticed the large bluebottles during her morning beach walk. (ABC Gold Coast)

Gold Coast resident Tera Jesperson said she saw bluebottles the size of a fist "all over the shoreline".

"It's quite scary because our dog was going up and sniffing them," she said.

"I don't want to be stung — I never have and never want to be."

The Australian Marine Stinger Advisory Service describes bluebottle stings as "instant and sharp" but not life-threatening.

The Royal Australian College of General Practitioners recommends removing any tentacles off the skin with gloves or tweezers before washing the sting with seawater.

Professor Pitt said researchers only concluded last year that five different bluebottle species existed, with the survival of larger stingers potentially assisted by warmer El Niño conditions this season.

Bluebottles cause an instant and sharp sting (file photo). (Supplied)

"The sail of the bluebottle can be offset either to the left or the right of the body's axis," she said.

"It's like having a yacht sailing on two different tacks — you'll get some more commonly deposited on beaches under north-easterlies or some more commonly deposited under north-westerlies."

Gold Coast resident Mark Wallace said he had seen similar large bluebottles further south when he was a beach inspector at Manly, Sydney.

"We could always tell when they'd come in because you'd hear a scream," he said.

"I don't know what the phenomenon is, but there must be something."