With eight arms and three brains, octopuses look kind of intimidating. But, like the giant pacific octopus, some can grow to over 30 feet across and weigh as much as 150 pounds.
They certainly could hurt a human at that size, but are they aggressive enough to try?
Are Octopus Dangerous to Humans?
If you look at the various cephalopods and octopuses found in our seas, you’d expect the largest to be the most dangerous.
The average giant pacific octopus is about the same size as a six-foot human, and we all know how much damage they can do!
However, it’s the smallest, rather than the largest octopus, that poses the biggest threat to humans.
Despite its size and potential to cause harm, the giant pacific octopus rarely attacks.
Not, for that matter, does the diminutive blue-ringed octopus, but it’s still responsible for more human fatalities than any other species of cephalopod.
The blue-ringed octopus only measures approximately 12 cm across, but it “contains enough venom to kill more than 20 people.”
Although all octopuses are venomous, only the blue-ringed octopuses contain enough to threaten a human’s life.
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The California two-spot octopus is also venomous but it isn’t life-threatening for humans, causing only “nausea and headaches.”
The blue-ringed octopus carries a potent venom that can kill an adult human within a few hours.
The venom, known as tetrodotoxin (TTX), is a potent neurotoxin that blocks “the transmission of nerve impulses.”
This action prevents muscles from contracting, causing respiratory failure and paralysis.
Death is usually caused by suffocation due to the paralysis of the diaphragm.
Blue-ringed octopuses aren’t particularly aggressive but will bite in self-defense if they have no option of escape.
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Unfortunately, just 1 mg of this venom is enough to kill a human, so it won’t take much.
You probably won’t even notice a bite from a blue-ringed octopus. Their beaks are so small that a bite barely even results in a drop of blood, but it’s still potentially deadly.
Blue-ringed octopuses use their venom to paralyze their prey, transferring it through their saliva as they eat.
Do Octopus Attack Humans?
Octopus are rarely aggressive towards humans but do an attack on occasion. When octopuses attack, it’s rarely because they want to eat you.
Even when an octopus does attack is usually acting in self-defense rather than out of sheer aggression.
Last year, a former lifeguard named Lance Karlson became the victim of an octopus attack.
Mr. Karlson was at Geographe Bay in Western Australia when encountering the world’s angriest octopus.
He was strolling on the beach with his two-year-old daughter when he first spotted the animal.
At first, he mistook it for a stingray until he “saw the tentacles of an octopus come out of the water and lash out at a seagull.”
A short while later, Mr. Karlson entered the water for a quick swim and saw the octopus again.
This time it was sitting on a pile of crab shells on the ocean floor. Mr. Karlson was only aware that he’d swam too close to the octopus when he was hit across the arm.
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A moment later, tentacles wrapped themselves around Karlson’s neck.
With his goggles fogged up and the water suddenly murky from the surprise attack, Karlson “swam back to shore in pain.”
The tentacles left raised marks across his skin, producing a burning sensation that only stopped stinging after pouring coke over the wounds.
Octopus attacks more commonly involve divers and rarely occur in shallow water.
In 2014, Russian diver Dmitriy Rudas filmed a video showing a giant pacific octopus wrapping its tentacles around the arms and equipment of a fellow diver.
Despite the size of the cephalopod, the diver remains completely calm throughout the experience.
He first removes the tentacles from his body before allowing the octopus to grab his camera equipment.
Although it takes some time to disentangle himself from his attacker, at no point does the octopus show any signs of real aggression.
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That wasn’t the case when a giant pacific octopus attacked Doug Pemberton in 2008.
Diving off the coast of British Colombia, at a place called Tzoonie Narrows, Pemberton. Fellow diver Danny Mauro was on hand to capture the struggle on video.
Doug wrestled the animal, trying to release himself from its strong grasp but, in doing so, found himself moving ever closer to the creature’s beak.
Eventually, the diver managed to get away, and the octopus retreated into a crevice in the rocks.
But, had he been bitten and injected with the octopus’s venom, things could have turned nasty, as Jamie Bisceglia discovered.
Bisceglia was competing in a salmon fishing competition when she saw a friend had accidentally hooked a small octopus.
So she decided to have a little fun with the creature, placing it on her face to pose for a photo.
Unfortunately, the creature bit into her face with its hard beak and held on tight. “When its beak entered my chin, it was the most intense pain,” Bisceglia said.
When Bisceglia finally managed to remove the animal, she bled profusely from the bite.
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Soon after, her face began to swell, and she lost all feeling on one side.
The venom had caused partial paralysis and extensive swelling to her face and glands. “My glands were completely swollen,” she said, “and then the left side of my face was completely paralyzed.”
Bisceglia was given antibiotics and other medications to counteract the venom at the hospital. However, she suspects the scar from the bite will stay with her forever.
Can an Octopus Hurt You or Kill You?
The above stories highlight the fact that even though octopuses rarely attack, they can still hurt you.
There are mythical stories of giant cephalopods attacking ships, but the terrifying stories are much more modern and true.
The blue-ringed octopus is responsible for three known deaths and many close calls.
For example, in 2018, an Australian man named Aaron Pix was rushed to the nearest hospital after finding a blue-ringed octopus in his pocket.
The small, brightly colored cephalopod hid in a shell his daughter had picked up on the beach.
Mr. Pix had put the shell in his pocket for safekeeping, but he discovered a dangerous stowaway inside when he got home.
Mr. Pix was rushed to the hospital and kept under observation for three hours before being released.
Mr. Pix knew exactly what he was dealing with, quickly identifying the octopus by its distinctive blue rings and bright yellow coloration.
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Not everyone is as well-informed. Last year, Kaylin Phillips had no idea she was dicing with death.
To her, the tiny, colorful sea creature looked completely harmless. Little did she know that it packs more venom into its tiny body than the most venomous snake in the world.
The only octopus likely to kill a human is so small, that it wouldn’t consider eating one. So stories of man-eating octopuses are the stuff of myth and legend… or are they?
We know so little about the most intelligent invertebrates that a few surprises could easily lurk on the seafloor.
What Do You Do If an Octopus Attacks You?
If an octopus approaches you, the best thing to do is swim away. Octopuses aren’t aggressive animals but they are territorial so, once you’re out of their territory, they’ll usually lose interest.
In the event of an octopus attack:
#1 Swim Away
A small to medium-sized octopus isn’t as powerful as a giant pacific octopus and, even if it latches onto you, you should be able to swim away.
Instead, try to propel yourself forward and pull away from the octopus’s tentacles. If that doesn’t work, try the next step.
#2 Put Pressure on its Arms
Octopuses are strong and naturally curious, but they also tire quickly. Putting pressure on its arms and gently squeezing them will encourage it to let go
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#3 Avoid Getting Wrapped Up
An octopus will usually secure itself to a rock or piece of coral before reaching out to grab you.
Try to stop it from wrapping itself around your body when it does this. If the octopus manages to pin your arms to your body, you’ll have trouble getting free.
#4 Peel the Suckers From Your Body
Do this in the same way as you’d peel up a bath mat. Once you have loosened one of the octopus’s arms, try to prevent it from reattaching.
#5 Lean Back
An octopus secured to a rock or still partially inside its den will be unwilling to launch itself into the water.
If you lean back, pulling away from whatever’s mooring your attacker, you force it to leave its place of safety or let go of you.
#6 Protect Your Mask and Regulator
Octopuses prefer deep waters so most encounters involve scuba divers, rather than swimmers.
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The greatest danger for a diver is if the octopus manages to remove the regulator, cutting off the air supply.
Having your mask dragged from your face is unpleasant and impairs visibility, but it’s not life-threatening.
#7 Turn Somersaults
If the octopus detaches itself from its mooring but remains attached to you, turn somersaults in the water. This will irritate the octopus, encouraging it to let go.
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According to David Scheel, a professor of marine biology, aquarium husbandry, and animal behavior at Alaska Pacific University, the most important thing is to remain calm.
In the vent of an octopus attack, he advises you to “Keep your arms free, protect your regulator and mask, and move slowly but firmly to reduce the chance that you injure the octopus.”
In most instances, he says, “the octopus will tire before you do.”
What To Do If Bitten By a Blue-Ringed Octopus?
That advice is all well and good, but it’s of little help to someone who’s just been bitten by a blue-ringed octopus.
That type of attack requires a very different reaction and a quick dash to the nearest hospital.
You won’t necessarily notice a bite from the minuscule blue-ringed octopus but, if you have been bitten, medical experts say you’ll become aware of some of the following symptoms within the first 10 minutes:
- A burning sensation
- Loss of feeling
- Difficulty breathing or swallowing
- Vomiting and nausea
- Difficulty speaking
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If you experience any of these symptoms after swimming in the sea, you should seek immediate medical assistance.
You should also immobilize the affected limb, applying a wide bandage to the entire area and stabilizing it with a splint.
Most people make a full recovery from a blue-ringed octopus bite.
Octopuses don’t often attack people, and even when they do, they rarely cause death, let alone eat anyone.
For the most part, these intelligent invertebrates are solitary and shy, avoiding contact with humans as much as possible.
There may be stories about giant man-eating cephalopods, but these sound more mythical than real.
Currently, the most dangerous octopus in the ocean is one of the smallest, rather than the biggest, and, at just 12 cm long, it’s certainly not planning on eating you!
Nicky is a British adventurer and animal lover who spends her time exploring the natural world and writing about her experiences. Whether on horseback, underwater, running, hiking or just standing with a fishing rod in hand, she embraces everything her adopted home of South Africa has to offer.