9 Surprising Facts About Octopuses

Discover nine new facts about octopuses that will leave you in awe of these amazing sea creatures.

Mar 30, 2023By Donna Hobson
surprising facts about octopuses

Octopuses are one of the most fascinating creatures on Earth, thanks to their unique characteristics and impressive abilities. You already know they have eight arms, but did you know that each arm contains its own brain? Or that an octopus can open a childproof bottle.

Octopuses are invertebrates which means they have no bones or skeletal system. This may seem strange until you realize that invertebrates comprise 97% of the animal kingdom. Here is a collection of more intriguing facts about octopuses.

Octopuses Have Been Around for Millions Of Years

octopus ancestor sea creature

The oldest eight-limbed octopus fossil on record dates back to the Carboniferous period, some 296 million years ago. This specimen may have resembled a "globular splat" more than the features of today's octopuses, but the creature possessed the characteristic eight arms and two eyes; it may even have possessed an ink sac.

Still, recent discoveries lead scientists to believe that octopus's ancestors may have possessed ten arms and lived more than 330 million years ago.

They Have Venom

blue ringed octopus venomous sea creature

Scientists believe all octopuses have some venom created by their internal bacteria, but most don't possess enough to harm people. Still, you wouldn't want to cross paths with a blue-ringed octopus; a single bite could paralyze you within minutes.

They Have Three Hearts

octopus swimming in open water

If you're a fan of quizzes, you may have heard this popular trivia fact: octopuses have three hearts. One heart pumps blood to the octopus's organs, while the other two pump blood through their gills. When octopuses swim, the heart that transports blood to their organs stops beating, meaning they tire quickly, and this could be why many octopuses prefer to crawl rather than swim.

Another interesting fact is that an octopus's blood is blue. It may seem like a strange concept to us, but the only reason our blood is red is the presence of iron. In contrast, an octopus has copper-based proteins in its blood, known as hemocyanin, which gives the blood its blue hue.

Octopuses Can Mate for Several Hours

octopuses mating

Male octopuses use their hectocotylus (a kind of modified arm) to deposit spermatophores into the female's cavity. But, depending on the species, this mating process can take hours. During that time, the male risks being eaten due to the female's cannibalistic instincts. For this reason, the male will often mount the back of the female or mate from a distance.

However, both parents will die shortly after creating a new life. The male usually dies a couple of months after mating, while the female dies not long after the eggs hatch. The main reason is the mother will stop eating and direct her full attention to protecting her eggs.

They Are the Smartest Invertebrates

octopus opening a jar

Not only do octopuses have the highest brain-to-body ratio of any invertebrate, but they have also demonstrated their intelligence through several scientific experiments. Tasks completed by octopuses include finding their way through mazes, opening childproof bottles, using their abilities to deceive (for example, pretending they are a moving rock), and distinguishing one human being from another.

They Have Impressive Color Changing Abilities

octopus camouflage mimic rock

The cells of an octopus contain chromatophores, which give this sea creature the ability to change color. This skill is primarily used for camouflage and communication. Still, it has some other interesting applications - one study showed that octopuses would change their color to the beat of the music.

Some octopuses take this skill a step further by changing the texture of their skin. This allows them to have a smoother or bumpier appearance to blend in with their surrounding foliage. Of all octopus species, the mimic octopus displays this behavior most impressively and can change its appearance to mimic other sea creatures, such as venomous sea snakes or poisonous flatfish.

Their Limbs Have A Mind Of Their Own

octopus arm tentacle suckers

The octopus' eight arms are perhaps its most prominent feature, but these limbs have a mind of their own. Around two-thirds of all the octopus's neurons are located within these appendages, which means the arms can touch, taste, and take their own actions without relaying information to the brain.

These neurons cement the octopus's status as the most intelligent invertebrate on Earth because they effectively have nine brains (a mini one in every arm and the main one at their center).

Being invertebrates means these creatures lack a skeleton, which leaves these crucial limbs vulnerable to damage. Thankfully, they can start to regenerate a new limb almost immediately after another tentacle has been damaged.

They Enjoy Their Own Company

octopus house in the sea

Octopuses spend most of their lives alone and generally only interact with other members of their species for mating. These solitary creatures build their homes in corals and rocks, which they fiercely defend against intruders. Often, they will scatter stones and shells to disguise their dens and make predators less likely to approach.

They build these dens using rocks which they move around with their powerful arms and suckers. To complete the house, an octopus may create a "rock door" which they can pull to a close when they're at home.

Octopus Ink Is Potent

octopus squirting ink

Octopuses often squirt a cloud of ink to hide from predators, but it serves several other purposes. Within the ink is a compound called tyrosinase which can cause a blinding irritation to the eyes while muddying an animal's sense of taste and smell. The ink is so potent that it can kill the octopus if they fail to escape from their own cloud in time.

Donna Hobson
By Donna Hobson

Donna believes that keeping a pet is the key to a happy life. Over the years, many creatures have passed through her home - Sooty the cat, Millie the rabbit, Stuart (Little) the guinea pig, and Trixie the tortoise, alongside her pet goldfish, Zippy, who lived to the grand old age of 24 years! She currently resides with her black kitten Jinx and an aquarium full of fish and snails to entrance them both. When she is not looking after her pets, Donna enjoys researching and writing the answers to all your pet-related wonders.