BiologyCoachOnlineBlog

Last week's #MysteryCreature was the Greater Blue-ringed Octopus (Hapalochlaena lunulata).

Despite its common name Hapalochlaena lunulata is a comparatively diminutive mollusk: 4-inches (10cm) from arm to arm. [The term "greater" refers to the diameter of its rings: around 8-millimeters, much larger than those of other species in the genus.] The greater blue-ringed octopus abundant in the warm tropical and subtropical waters of the Indo-West Pacific. H. lunulata can be observed from Sri Lanka to the Philippines and from Australia to the shallows of southern Japan. H. lunulata inhabits mixed seabed environs and shelters in burrows. H. lunulata feeds primarily on crustaceans bivavles. H. lunulata is a solitary mollusk (except, of course, during breeding). Females lay 60 to 100 eggs which they protect under their arms during incubation (approximately one month).

The greater blue-ringed octopus has two different venom glands: the first it uses to subdue and kill its prey; the second, a neurotoxin, is used for defense. Abite from the greater blue-ringed octopus can be fatal to even humans. While the bite itself is painless, the effects of the toxin may be anything but. The first phase of poisoning - which usually occurs within the first 30-minutes after contact - is characterized by facial paresthesia, hypersalivation, and cyanosis. The second phase - which generally occurs after about 8-hours - is characterized by hypotension and systemic spastic muscle weekness. Death from respiratory paralysis usually occurs about 20-minutes after phase two symptoms appear.