SURF Life Saving WA has issued a warning over five sightings of the deadly blue-ringed octopus at northern beaches.
There have been five separate sightings of blue-ringed octopuses on the reef at Yanchep Beach in the past two days.
Temporary signage has been erected to warn beach users.
Beachgoers are being urged not to attempt to touch the creatures, which are highly venomous dead or alive.
Yanchep man Hidde Wildenburg posted a photo of two of the octopuses on Facebook.