These are the deadliest octopuses in the world – and one has enough venom to kill dozens of humans within minutes

These are the deadliest octopuses in the world – and one has enough venom to kill dozens of humans within minutes

All octopuses produce venom, but very few are actually deadly. From the lethally infamous blue-ringed octopus to lesser-known species with surprising tactics, discover which octopuses possess potent venom

This octopus, found in the surrounding waters of Coiba National Park, a UNESCO World heritage Site, is a true master of disguise. It is perfectly camouflaged to blend in against the volcanic ocean floor. © Irene Mendez Cruz

Freya Parr

Published: May 1, 2025 at 8:34 am

All octopuses are venomous, although the venom of some species is more toxic than others. One particular species is the deadliest of all, dangerous to humans as well as other sea creatures. 

Most venomous octopuses

Blue-ringed octopus

A tiny blue-ringed octopus rests on white coral reef
A tiny blue-ringed octopus rests on white coral reef (credit: Getty Images)

Despite its small size, the blue-ringed octopus holds enough venom in its body to kill 26 adult humans within minutes – and there is no known antivenom. Its venom is a thousand times more toxic than cyanide and will paralyse its prey, making it one of the deadliest sea creatures in the world. The blue-ringed octopus should be approached with caution, due to the sheer potency of its venom. However, the blue-ringed is the only octopus that remains dangerous to humans. 

Giant Pacific octopus

The giant octopus in the dark water
Giant Pacific octopus (credit: Getty Images)

This North Pacific octopus’s venom is used to subdue its prey – rather than for self-defence against humans. It can inject venom into its prey (predominantly shellfish) using its sharp beak. But the giant Pacific octopus has another self-defence mechanism: it can produce black ink to cloud the water around it. 

California two-spot octopus

The California two-spot octopus in disguise against a coral reef
This California two-spot octopus (Octopus bimaculoides) is a master of disguise (credit: Getty Images)

The California two-spot octopus has venom that will paralyse its prey, particularly small fish and crustaceans – although it’s not considered dangerous to humans. That said, its bites could cause some irritation. 

Blue-lined octopus

Technically, the blue-lined octopus is a type of blue-ringed octopus, but a new use of its deadly venom was discovered recently that earns it another place on this list. The male blue-lined octopus injects females with a tiny amount of venom before they begin mating, so as to avoid being cannibalised during reproduction. The effect is that the female is left immobile, which enables the male to mate successfully. 

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