The southern blue-ringed octopus (Hapalochlaena maculosa) is one of three (or perhaps four) highly venomous species of blue-ringed octopuses. It is most commonly found in tidal rock pools along the south coast of Australia. As an adult, it can grow up to long (top of the mantle to the tip of the arms) and on average weighs . They are normally a docile species, but they are highly venomous, possessing venom capable of killing humans. Their blue rings appear with greater intensity when they become aggravated or threatened. Description The blue-ringed species are known for their small size, yet the southern variety is hailed as the largest of the genus. As a result, they have been classified as their own species. From arm to arm, most of these octopuses are no larger than 20 centimeters. This is larger by roughly 5 centimeters on average with other varieties of the blue-ringed octopus. When at peace, their coloring is often a drab, mucus like color. However, once it feels sufficiently threatened, the eponymous blue-rings suddenly appear. These octopuses have an average of about 60 rings that have multilayer reflectors that allow them to flash a blue green color. These rings typically appear about 6 weeks after hatching (Mäthger et al.). For the rings to illuminate and glow, the muscles around the rings must contract while the muscles above them must relax (Mäthger et al.). This method of muscle contraction and relaxation has not been seen in other illuminating animals (Mäthger et al.) Nomenclature Like other species of the blue-ringed octopus, this variety is named for the vibrant blue rings that it displays when agitated. Range and habitat Found along the southern coasts of Australia, H. maculosa inhabits crevasses and cracks in the rocky reefs signature to this section of the Australian coast. In addition, the octopus enjoys a proximity to the plentiful forests of seagrass. Behavior Despite their highly toxic venom, southern blue-ringed octopuses tend to be passive and relatively harmless unless provoked. They generally only use their toxins when hunting or when provoked. These creatures are nocturnal, primarily active at night. They can jet out water to move more efficiently as well. In addition, it was found that southern blue-ringed octopuses have at least slightly more acute olfaction (smell) sense which may affect choice in mate (see Breeding, below). Burrowing is also normal of this species. Diet The prey of H.