Hapalochlaena maculosa is the southern blue-ringed octopus, also called the lesser blue-ringed octopus. Lesser refers to the rings, which are smaller and usually more numerous than those of H. lunulata. The animal itself can be longer in total length, on the order of twenty centimeters from mantle to arm tip, while staying very light. A figure around twenty-six grams is often quoted. Length without weight is a good reminder that an octopus is mostly arms and water.
Its map is the southern coastline of Australia and the water around Tasmania. It is not only a tide-pool animal. Records take it down to about fifty meters, which is still the nearshore sea, but it is enough to put this species beyond the ankle-deep picture that follows the whole genus around. Rocky reefs, sand, and the kind of bottom a diver or a fisher might actually meet are all in play.
This is also the species that has been watched most carefully when it comes to mating. Body size matters. Larger males secure more copulations. Males will mount other males. A mating lasts longer when the female has not recently mated with someone else, and the male does not seem to be choosing females by smell in any simple way. Researchers have also shown that this species can recognize other individuals by a combination of touch and chemical cues, which is a quieter kind of intelligence than the rings and just as real.
If you are reading a paper about blue-ringed octopus behavior and the location is southern Australia, you are very often reading about H. maculosa. The rings are the family resemblance. The life history details do not always transfer, unchanged, to the tropical species.