The Blue-Ringed Octopus, affectionately called the BRO, are a highly sought after underwater photography subject, topping the holy grail critter list for many underwater photographers and naturalists. There are approximately 5-10 different types of species found. They were originally discovered inhabiting the western coast of Australia, and they are the only lethal octopus known to man.
The Lesser Blue ringed octopus, Hapalochlaena maculosa (found only in Australia), and Greater Blue Ringed Octopus, Hapalochleana lunulata, are the most common. The species are divided and named not by the size of the animal but by the amount of rings.
They possess eight arms with dual rows of suction cups, a large head and two big eyes.