The Biology of the Venom of Hapalochlaena maculosa
Hapalochlaena maculosa, also commonly known as the blue-ringed octopus, is a golf ball-sized cephalopod inhabiting the waters around Tasmania and southeastern Australia with a highly potent neurotoxin that it uses as a predatory and defensive mechanism. H. maculosa does not actually synthesize its venom, but rather, the neurotoxin (known as maculotoxin) is produced by a bacterial symbiont of the octopus that lives in its salivary glands. While not overly aggressive, H. maculosa has been known to bite humans when they disturb the usually reclusive octopus. Tetrodotoxin (TTX), the principle component of maculotoxin, inhibits the nervous system by binding to sodium channels on nerve cells to prevent the flow of sodium and release of neurotransmitters. Recent findings have shown that there are sodium channel variants that are either immune or resistant to tetrodotoxin. In most humans, however, victims of the blue-ringed octopus’s neurotoxin will enter into increasingly dangerous stages of paralysis, which will often end in death of the victim without medical assistance. Sustained medical care for the duration of the toxin’s effects will improve the likelihood of a victim’s survival, but mortality rates are still staggeringly high despite current medical efforts and attempts to find an antidote.
Australia is home to many of the most venomous animals in the world. Many people know that the bites from many of Australia’s snakes and spiders or the stings from its jellyfish and scorpions can be lethal, and oftentimes images of a person writhing in agony as a toxin courses through his or her body come to mind. However, one of Australia’s deadliest creatures has a toxin that works in a very different way. The venom of Hapalochlaena maculosa, or the blue-ringed octopus, causes relatively little pain, but its effects are much more terrifying for the victim. This venom, known as maculotoxin, is an...