Blue-ringed Octopus: How Deadly Is It?

The Blue-ringed Octopus, nicknamed as the BRO, is one of the ocean’s most lethal but fascinating creatures. As the name denotes, it is known for its bright blue rings that appear when threatened.

Like any other octopuses, it has eight tentacles and a sac-like body. But, no need to panic, the blue-ringed octopus is not aggressive!

It only attacks humans when it feels in danger like if you are trying to corner a blue-ringed octopus it might become aggressive and attack.

However, despite its small size, it carries enough venom to kill twenty-six adult humans within minutes. Their bites are tiny and often painless, with many victims not realizing they have been envenomated.

Not until respiratory depression and paralysis start to set in.

Blue-ringed Octopus
How Deadly is the Blue-Ringed Octopus? – (

Where can we find the Blue-ringed Octopus?

They often dwell in the temperate waters of Australia, Indonesia, New Guinea, Malaysia, Japan, and the Philippines.

If you want to spot this cute but deadly animal on your dive in the Philippines, you can look for them at dive sites in Anilao, Puerto Galera in Luzon, Dauin, Leyte, Bohol, and Cebu in the Visayas.

They like to stay in shallow reefs and tidal pools, often hiding in cracks, crevices, and sandy bottoms.

Mactan Island coastline facing Olango Island is also well known for its blue-ringed octopuses. You can easily find them along Mactan island, as well as around Olango Island.

How Deadly is the Blue-ringed Octopus?

Aside from its bright blue rings, the blue-ringed octopus is also known for its potent toxin used for hunting and attacking when sensing danger.

This small mollusk (it is only about the size of a human hand for the biggest!) is packed with two types of toxins, one for hunting and the other for self-defense.

The blue-ringed octopus ejects Tetradoxin, a harmful toxin that could paralyze and kill a human adult in mere minutes (it is 1,200 times more toxic than cyanide). It is the same toxin that the pufferfish and cone snails have.

The toxin is produced by the bacteria found in its salivary glands and not by the blue-ringed octopus itself. One milligram of it can kill a person.

An average-sized blue-ringed octopod has enough venom to kill 26 full-grown adults. What’s worse is that there is no known antidote! So keep your distance when you see one.

The second type of toxin it has is used to kill its prey. This venom is harmless to humans, but it is toxic enough to paralyze and eventually kill crabs and other crustaceans.

The blue-ringed octopus bites through the exoskeleton of its prey and releases the venom to poison it before consuming it. This octopus hunts at night, and they are also known for cannibalistic behaviors when fighting for territorial rights.

Blue-ringed Octopus Bite
A poisonous Blue-Ringed Octopus (Photo Credit: Reinhard Dirscherlullstein Bild via Getty Images)

How does the Blue-ringed Octopus Reproduce?

There are only four known species of the blue-ringed octopus, with Southern Blue-Ringed Octopus (Hapalochlaena maculosa) being the most common. The lifespan of a blue ringed octopus is approximately one to two years.

During reproduction, the male clutch onto the female, sometimes obscuring her vision. The male octopus then inserts his hectocotylus (the arm used to transfer spermatophore) into the female repeatedly.

The male dies after reproduction while the female-only lay a single clutch of around 50 to 100 eggs for about six months. At this time, the mother octopus does not eat while incubating and guarding the eggs with her life.

When the eggs hatch, the female dies because of starvation. Juvenile blue-ringed octopuses are as small as a pea, and they mature quickly for a year.

Girl Accidentally Brings Home Deadly Blue-Ringed Octopus From Beach

Facts About The Blue-ringed Octopus Bite

Often, the Blue-ringed octopus bite is notably painless. And also, which leaves a small bite mark and causes as little as two drops of blood.

However, the venom quickly takes effect, and in a few minutes, the victim will experience;

  • nausea,
  • dizziness,
  • severe fatigue,
  • vomiting,
  • numbness,
  • loss of senses,
  • loss of motor skills,
  • increased heart-rate,
  • difficulty in breathing and swallowing.

If bitten, one should seek medical care immediately. After about 15 hours, the muscles will start working again. People who usually survive the first 24 hours make a complete recovery.

But don’t worry, death from the venom of a blue-ringed octopus is not as common as you think. The blue-ringed octopus is also not aggressive. It only attacks humans when handled or cornered.

Nevertheless, you should always be mindful of where you step on rocky shores and when swimming in shallow waters, scuba diving, or snorkeling.

Their horny beak is strong enough to penetrate through a wetsuit.

What are the Symptoms of their Bite?

When human contact with a blue-ringed octopus occurs, it is usually accidental. Avoid handling this octopus because its sting contains tetrodotoxin, which paralyzes the victim (similar to pufferfish poisoning).

The sting is often fatal. The blue-ringed octopus injects its toxin by biting. Most bites cause minimal pain for the first 5-10 minutes then begin to throb and may get numb and involve the rest of the arm (or extremity) bitten.

Bleeding may also be excessive accompanied by numbness, nauseavomiting, changes in vision, and difficulty swallowing.

If medical care is not provided emergently, respiratory failure may occur, which may lead to cardiac arrest, and death.

How do you treat a Blue-ringed Octopus bite?

This bite is considered a medical emergency so do not wait for symptoms to develop; quickly get the person bitten out of the water. And, if possible, call 911 and consider transport to the nearest hospital.

However, if you are not near a hospital, you can use the pressure immobilization technique:

  • Use an elastic bandage (similar to ACE bandage) to wrap the limb starting at the distal end (fingers or toes) and wrap toward the body. It should be tight, but the fingers and toes should remain pink so that the circulation is not cut off.
  • The extremity should also be immobilized with a splint or stick of some sort to prevent it from bending at the joint(s).
  • The elastic bandage should be removed for 90 seconds every 10 minutes and then reapplied for the first 4 to 6 hours. Hopefully, medical care can be received within this time period.
  • If 30 minutes or more have passed since the blue-octopus bite, the pressure immobilization technique is not likely to be helpful.

The duration of life-threatening symptoms is usually from 4 to 10 hours. After that time, surviving patients typically show rapid signs of improvement.

However, if the patient is having difficulty breathing, assist with mouth-to-mouth ventilation.

On the other hand, Neostigmine (Prostigmin Bromide) and edrophonium (EnlonTensilon) have shown benefit in some reports of tetrodotoxin intoxication.

For example, pufferfish toxin similar to the blue ring octopus toxin, but has not undergone clinical trials in blue-ringed octopus envenomations.

But, there is no antivenin available for blue-ringed octopus bites at the moment.

Resourceful References;

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