Octopuses

What has three hearts, blue blood, no bones and nine brains? It’s no sci-fi monster, it’s an octopus. Octopuses are some of the most fascinating animals in the sea; able to change their colour, texture and shape in less than a second, they are masters of disguise. Under their alien-looking exteriors lies a nervous system unlike anything else on Earth. These slippery, shapeshifting creatures have inspired stories and prompted scientific investigations – and they still hold many mysteries.

How do octopuses change colour?

Chromatophores (cells that contain colour) give octopuses their colour shifting abilities and the animals can control which colour is visible using their muscles. The Science+Nature team spoke with marine ecologist Erin Spencer on our Mysteries of Science podcast, who explained that when those muscles open, a whole different colour appears on the octopus. This ability is used for camouflage (a means of disguise). Some species – such as the mimic octopus – use this to take on the appearance of other animals entirely.

Are octos super-intelligent?

More amazing than their colour-shifting talent is their intelligence. Researchers have watched octopuses open jars, solve puzzles and navigate mazes. University lecturer and former zookeeper Heather Browning said octopuses are always trying to escape and explore the environment; and wildlife presenter Chris Packham told Mysteries of Science that he once found an octopus on the shore while on a university field trip. He decided to study it in his hotel bath tub – which he had filled with sea water; only to hear it, later that evening, slapping around as it tried to make a night-time escape. The animals’ inquisitiveness makes them both fascinating and frustrating to study.

The veined octopus, found in the Pacific Ocean, is known to use clam and coconut shells as make-shift shelters, a rare example of animals using tools once thought to be exclusive only to mammals. Octopuses can also watch human behaviour and remember it, as well as learn by watching other octopuses. These behaviours hint at communication and social skills that scientists are only just beginning to understand.

One of the most mind-blowing features of octopuses are their nine brains. With one central brain and a “mini brain” in each arm (commonly called tentacles), octopuses challenge our understanding of what it means to be conscious. Each arm can sense, explore and make its own decisions, giving the octopus fast reaction times. Could there be a mind in each brain? Do they think independently?

Just like us?

Scientists think octopuses might be able to dream. Researchers have noticed sleep stages similar to those in mammals, as well as “skin flashes” that could suggest they’re responding to mental images. Could they even be having “nightmares”?

In 2021, the UK Government recognised cephalopods (a group of marine animals that includes octopuses, squids and cuttlefish) as “sentient beings” – meaning they’re capable of experiencing feelings. “To be sentient means that you have a point of view and experience of the world,” said Browning.

There is still a lot to learn. “It’s a frequent saying that we know more about deep space than we know about our deep oceans,” said Packham. Only about 5% of the ocean has been explored and new octopus species are being discovered all the time. These animals may have complex emotions and personalities which we are only just starting to discover.

Octopuses make us question what we know about intelligence, consciousness and curiosity. The more we study them, the more we find out about how animals may think, feel and “dream” – and it could help us to learn more about ourselves too.

Fortune-telling creature

There was one octopus who was able to “predict the future”. In 2008, Paul the Octopus at an aquarium in Germany correctly “guessed” the winning football team in four out of six European Championship games. Food was placed inside two boxes, each box with a different team’s flag. Whichever box Paul chose, that was the prediction. He repeated the feat by “guessing” the winners of all of Germany’s 2010 World Cup games.

In Hawaiian culture, the god Kanaloa looks like an octopus; and a Hawaiian creation myth says that the universe is made up of an older one that no longer exists, the only survivor of which is an octopus.

There’s no evidence to suggest that octopuses have any real future-predicting abilities but it shows how respected and fascinating they are.

First published in The Week Junior Science+Nature, issue 95, December 2025.