[3] 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.

[2] Blue-lined octopuses tend to swim around shallow areas of coral reefs and tide pools.

Prey for blue-lined octopuses mostly consists of crustaceans and stomatopods, however in captivity they have been recorded to eat live fish, suggesting they do in the wild as well.

[4] The blue-lined octopus is about the size of a golf ball, having a mantle length of 45mm, it is the smallest out of the four species that make up the genus.

While at rest blue-lined octopus are highly camouflaged, due to the presence of chromatophores under the skin they can rapidly change body coloration, using aposematic signals to display bright blue lines to predators.

[3] After some time, symptoms of the injection include loss of feeling in the tongue/lips, muscle weakness/paralyzation, respiratory failure, unconsciousness, and eventually death.

Furthermore Hapalochlaena is the only genus to produce this biotoxin, which is thought to have played an important role in the evolution of the species.

[5] Blue-lined octopus are commonly found off the coast of Australia inhabiting shallow tropical and subtropical reef waters.