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Though diminutive, the blue-ringed octopus boasts the most powerful poison among its fellow cephalopods.(Image credit: Belive… via Getty Images)ShareShare by:
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Octopi have cultivated a reputation as astute masters of camouflage and remarkably bright beings. However, some are distinguished for a more menacing attribute: Their capacity to kill.
A particular group — the blue-ringed octopus (genus Hapalochlaena) — is notably hazardous. But what renders this animal so lethal?
Blue-ringed octopi possess a lethal cocktail known as tetrodotoxin (TTX), a strong neurotoxin with the ability to induce paralysis in living beings, humans included. Tetrodotoxin is best recognized in connection with pufferfish — improperly prepared “fugu” can prove fatal to those who ingest it. Tetrodotoxin is a staggering 1,200 times more virulent to humans than cyanide, and presently, there is no established remedy.
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All four octopus species within the genus Hapalochlaena contain tetrodotoxin, thus constituting the four most poisonous varieties of octopus: the greater blue-ringed octopus (H. lunulata), the southern or lesser blue-ringed octopus (H. maculosa), the blue-lined octopus (H. fasciata) and the common blue-ringed octopus (H. nierstraszi). These cephalopods, adorned with their shimmering blue circles, certainly possess aesthetic appeal, but also pose a threat.
All octopods — a grouping of sea creatures that includes octopi — harbor venom, yet the potency of this venom varies among different species, noted Michael Vecchione, an associate zoologist at the Smithsonian Museum of Natural History. “The blue-ringed is possibly the most venomous,” he communicated to Live Science via email, largely because its habitat consists of shallow waters teeming with predators that could wish to consume this octopus. Its venom constitutes a defense mechanism.
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“Venomous secretions fall within a diverse array of naturally occurring toxins produced by octopods,” Vecchione elaborated. It is important to note, however, that blue-ringed octopi do not synthesize tetrodotoxin independently. Instead, symbiotic bacteria residing within their salivary glands are responsible for its production, as reported by the Australian Institute of Marine Science.
These octopi inhabit coral reefs and rocky seafloor habitats throughout the Pacific and Indian oceans. They tend to dwell at depths of approximately 66 to 164 feet (20 to 50 meters), varying according to the particular species. They also exhibit diminutive size, spanning between 5 and 9 inches (12 to 22 centimeters) in length, inclusive of their arms.
“It seems logical that such a compact octopus would require exceptional capabilities to safeguard itself,” commented Bret Grasse, the cephalopod operations manager at the University of Chicago Marine Biological Laboratory, to Live Science.
This robust venom consists of various elements — such as histamine, acetylcholine and dopamine — but its chief ingredient is tetrodotoxin. Functioning as a neural inhibitor, it impacts nerve tissues through the obstruction of sodium channels — proteins within nerve cells crucial for facilitating communication between these cells and muscles. When tetrodotoxin acts upon these channels, it possesses the capacity to halt a creature’s respiratory muscles, thus ceasing breathing, and even cardiac function.
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This venom proves useful in combating predators and securing nourishment. Blue-ringed octopi commonly administer their venom through direct bites. Although researchers have detected a blue-ringed octopus’s venom across its anatomy, inclusive of its gills and the sac holding its internal organs, the highest concentration occurs in the posterior salivary gland, according to Grasse.
They are also able to discharge the venom within the ambient water. Neighboring organisms — be they predators or prey — that respire will ingest the contaminated water, which “can instigate the deceleration of their motor responses and lead to paralysis,” Grasse explained.
The role of venom is not restricted to predation and defense, as blue-ringed octopi additionally employ it during mating rituals, Grasse indicated. Consistent with other animals, the female blue-ringed octopus exhibits notably greater dimensions than her male counterpart — at times, reaching three to five times larger — thus, the male confronts risks throughout copulation, incorporating the prospect of being consumed.
Even though the blue-ringed octopus manifests some resistance to its individual toxins, it does not possess complete immunity. Consequently, the male has the ability to temporarily paralyze larger females utilizing venom for a duration sufficient to permit the exchange of a spermatophore.
Females further incorporate venom into the processes of egg laying, Grasse noted. They encase their eggs within layers of the toxin, intended to fend off predators.
Occurrences of humans suffering bites from blue-ringed octopi remain uncommon, as Grasse observed. At a minimum, there have been three documented fatalities stemming from the blue-ringed octopus — comprising two in Australia and one in Singapore, as per the Australian Institute of Marine Science.
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While this robust poison is capable of inducing an agonizing demise in a span as short as 20 minutes or extending to 24 hours, several individuals have survived to recount their experiences. The results are “actually remarkably unpredictable,” Grasse stated. “Certain episodes involving verified bites from blue-ringed octopi have yielded absolutely no repercussions.”
In a 2006 incident, a 4-year-old boy in Australia was bitten by a blue-ringed octopus. Rapidly, within 10 minutes of exposure, the boy vomited on three occasions, voiced blurred vision, and became unable to stand independently. Transported by ambulance to the emergency room, he was subsequently placed on a ventilator to aid respiration for a total of 17 hours. Astonishingly, merely 28 hours post the original bite, he was discharged free of any persisting complications. Grasse affirmed that pursuing medical intervention and the utilization of a ventilator represent the most prudent course of action under such circumstances.
This seemingly modest yet potent creature undeniably possesses self-preservation skills. “It represents a broadly employed advantage at their disposal, deployed across an assortment of contexts,” Grasse concluded.
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Elana SpivackSocial Links NavigationLive Science Contributor
Elana Spivack operates as a scientific writer based in New York City. She holds a master’s degree from New York University’s Science Health and Environmental Reporting Program, coupled with a bachelor’s degree from Kenyon College in Ohio. Her portfolio encompasses contributions to Inverse, Popular Science, BitchMedia, among others.
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