Octopuses, the eight-armed mollusks inhabiting the oceans, are much more than just invertebrates. They are known for their remarkable intelligence, problem-solving abilities, and almost alien-like biology.
1. Eight arms, nine brains?
An octopus has a central brain in its head, but a large portion of its neurons (about two-thirds) are located in its eight arms. Each arm can therefore operate, taste, feel, and move to some extent independently of the central brain.
It’s as if each arm has its own ‘mini-brain’, enabling the octopus to perform complex tasks simultaneously, such as opening a shell while other arms explore the surroundings.
2. Masters of camouflage and transformation
Octopuses are unparalleled masters of camouflage. Their skin contains thousands of specialized cells called chromatophores, which they can rapidly expand or contract to change color and even texture.
They can adapt to their environment in a fraction of a second, becoming virtually invisible to predators and prey. Some species, like the mimic octopus (Thaumoctopus mimicus), can even imitate the shape and behavior of other sea creatures (like venomous flatfish or sea snakes).
3. Problem solvers and tool users
Octopuses display remarkable problem-solving abilities. In experiments, they have learned to unscrew jars to get food, navigate mazes, and recognize objects.
There are also observations of octopuses using tools in the wild. For instance, coconut octopuses have been seen carrying empty coconut shells to use later as shelters – a clear example of planning and tool use.
4. Playful behavior
Researchers have observed behavior in octopuses that strongly resembles play, something usually associated with more intelligent vertebrates. They have been seen repeatedly ‘throwing’ objects like bottles against a water current and catching them again, seemingly for no purpose other than entertainment.
This playful behavior suggests a higher level of cognitive complexity.
5. Three hearts and blue blood
Octopuses have a unique circulatory system. They have three hearts: two pump blood through the gills (branchial hearts), and one larger heart (systemic heart) circulates blood through the rest of the body.
Their blood isn’t red like ours, but blue. This is because they use hemocyanin to transport oxygen, a protein containing copper (instead of iron like in our hemoglobin). Hemocyanin is more efficient at transporting oxygen in cold, low-oxygen environments.
6. Invertebrate, yet highly intelligent
The high intelligence of octopuses is particularly remarkable because they are invertebrates. Their evolutionary lineage separated from that of vertebrates (like birds and mammals) over 500 million years ago.
This means their intelligence evolved completely independently, raising fascinating questions about the evolution of cognition and consciousness. They are sometimes considered the closest thing to an ‘alien’ intelligence we know on Earth.
7. Short lifespan and tragic end
Despite their intelligence, most octopus species have surprisingly short lives, often only one to two years. Reproduction usually marks the end of their lives.
After a female lays her eggs, she stops eating and devotes herself entirely to guarding and caring for the eggs until they hatch, after which she dies of exhaustion. Males usually also die shortly after mating. This phenomenon is called semelparity.
8. Escape artists
Because they lack bones, octopuses are incredibly flexible and can squeeze through the smallest openings, as long as their hard beak (the only hard part of their body) fits through.
https://www.youtube.com/watch?v=E3N0i_KM8cI
This makes them notorious escape artists from aquariums. They are known to lift lids, slip through tiny cracks, and even crawl over land for short periods to get from one tank to another.
9. Ink as a diversion tactic
When threatened, octopuses can eject a cloud of dark ink. This ink not only serves as a visual smokescreen to escape predators (like sharks, dolphins, and moray eels) but also contains substances (like tyrosinase) that can irritate or numb the attacker’s sense of smell and taste.
10. Ability to regenerate
If an octopus loses an arm in a fight or to a predator, it can fully regrow it, complete with suckers and nerves, without scarring.
These regenerative abilities are an active area of research, as understanding this process could potentially have applications in human medicine.
