Blue-lined octopus


The blue-lined octopus is one of three species of highly venomous blue-ringed octopuses. It is most commonly found around intertidal rocky shores and coastal waters to a depth of between southern Queensland and southern New South Wales. It is relatively small, with a mantle up to in length. In its relaxed state, it is a mottled yellow-brown with dark blue or black streaks covering the whole body apart from the underside of its arms, but its vibrant blue patches appear as a warning when they feel threatened. Along with its other closely related species, the blue-lined octopus is regarded as one of the most dangerous animals in the sea, and its venom can be fatal to humans. The blue-lined octopus’s saliva contain a special neurotoxin called tetrodotoxin which causes muscle weakness and respiratory failure. It’s so lethal that it’s been estimated that the venom from a single 25 gram octopus can kill about 75 humans. It is one of the most common of several species of blue-ringed octopuses found in Sydney. Their size range from 4.5 cm, of an adult, to 5.5 cm.