Deadly blue-ringed octopus found on popular Sydney beach: 'It's agitated'

A group of hikers saw the creature change colours when one person 'stepped too close'.

A deadly blue-ringed octopus was spotted at a beach popular with families on the weekend as a stunned group of hikers managed to spot the tiny but lethal critter lurking not far from the public.

Michael Jarosky was leading the morning walk on Saturday when the group came across one of the world's most venomous marine creatures at Sydney's Clontarf Beach, which was only "a little bigger than a golf ball".

"I had planned a 'Spit Bridge to Manly Beach & Pizza' hike for 10 people," he told Yahoo News Australia on Monday.

"Twenty minutes into our hike, we were walking along and one of the hikers said 'look, a blue-ringed octopus!'. She took a picture, then handed me her phone."

A photo of a blue-ringed octopus at Clontarf Beach in Sydney's north. Another photo of it when it felt threatened and changed colour.
A group of hikers spotted a blue-ringed octopus at Clontarf Beach in Sydney's north, which changed colour in front of their eyes. Source: Supplied

"When I handed it back she stepped too close to 'Bluey' and he became agitated... that’s when he really showed off his colours," he recalled.

The creature was discovered on the sand of the harbour beach while the tide was out, just metres away from a popular cafe, and only a short walk from a children's playground and dog beach.

"It was just lying in the open on the wet sand, close to the break wall," Mr Jarosky said.

Warning to locals of Sydney beach

It was apparently the second time a blue-ringed octopus was spotted in Clontarf "in the past couple of months," with Yahoo News Australia also reporting on a swimmer being bitten by one nearby at Chinamans beach in March.

"Maybe we shouldn't take dogs there anymore," one local said in the comments after Mr Jarosky posted about the encounter to a local Manly Facebook group.

A photo of Clontarf Beach.
Clontarf Beach on Sydney's northern beaches is popular with families. Source: Google Maps

"That electric blue is such a warning!" one person said. "Makes me shudder," another agreed.

Luckily the beach was not busy at the time and no one was hurt. "There was one person playing fetch with their golden retriever in the water, 50m away," Mr Jarosky said.

Originally from Chicago, the now Sydney resident felt "honoured" to "see such a rare creature".

After spotting the "beautifully dangerous", blue-ringed octopus, the hikers continued their walk, but not before Mr Jarosky posted the warning on social media.

"Only then did I realise the 'wow' factor that the little guy would cause for the locals," he said.

Venom 1000 times more powerful than cyanide

The venom of a blue-ringed octopus — called tetrodotoxin — is known to be 1,000 times more powerful than cyanide on humans.

Their bites are rare, seldom break the skin and are often undetected, yet have catastrophic effects so they should be avoided at all costs.

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