Octopus

The octopus is a cephalopod with three hearts, blue blood, no skeleton, eight arms with their own neuron clusters, and a skin that thinks in color while the animal itself is color-blind. It evolved its complex [[nervous-system|nervous system]] entirely separately from ours — our last common ancestor was a worm-like creature ~600 million years ago — which means octopus intelligence is what intelligence looks like the second time it independently appeared on this planet.

Cognition isn’t centralized. Bodies are not just substrates for minds. The octopus is the proof.

Scientific

The octopus has roughly 500 million neurons — about the same as a dog. But unlike a dog, where the neurons cluster in a central brain, the octopus distributes about two-thirds of its neurons into its eight arms. Each arm contains its own ganglion (a neural cluster), and the arm can perform complex motor sequences — opening jars, hunting, manipulating objects — while semi-autonomous from the central brain.

In one striking experiment, a severed octopus arm continues to react adaptively to stimuli for over an hour: avoiding noxious substances, reaching toward food. The arm “knows” what to do without instruction from any head [1].

Other documented capabilities:

• Tool use. The veined octopus (Amphioctopus marginatus) collects [[coconut|coconut]] shell halves and assembles them into a portable shelter, carrying them between hunts. The first documented case of tool use in an invertebrate [2].
• Color matching without color vision. Octopus skin contains opsins — light-sensitive proteins typically found in the eyes — meaning the skin itself may detect color, even though the brain receives only monochrome images. The animal sees in black and white but adjusts to its surroundings in vivid color, possibly through the skin reading the environment directly [3].
• Individual recognition of humans. Captive octopuses have been documented to recognize and respond differently to specific individual keepers — feeding from one, squirting water at another [4].
• Play. When given novel objects (Lego, plastic pill bottles), captive octopuses manipulate them in ways that meet behavioral definitions of play — repeated interaction without nutritional or reproductive payoff [5].
• Dreams. Recent video evidence (Mather and Dickel, 2017) shows octopuses cycling through skin-color and pattern changes during what appears to be REM-equivalent sleep, suggesting they may dream — replaying or rehearsing visual experiences while unconscious [6].

The evolutionary chasm matters: the octopus and the human represent two independent solutions to “be a complex behaviorally-flexible animal.” Convergent evolution produced eyes, learning, problem-solving, and possibly subjective experience along two completely separate lineages. If we want to know what mind is in general — not just what it is in vertebrates — the octopus is the only second sample we have.

Cultural and mythological

The octopus shows up in human imagination as both kin and monster.

• Pacific Northwest Coast Indigenous traditions (Tlingit, Haida, Coast Salish) include the octopus as a respected being in carved poles and oral traditions — depicted with intelligence, sometimes as a teacher or as a gatekeeper to underwater realms.
• Hawaiian he’e / mākālei — the octopus as a god (Kanaloa) of the deep ocean, healing, and sometimes the underworld. Octopus-deities recur across Polynesian pantheons.
• Greek mythology — sea monsters with octopus features, including the kraken of later Norse imagination. European medieval bestiaries rendered the octopus as a maritime threat, framing distributed intelligence as alien menace.
• Minoan Crete (1500 BCE) — the most beautiful octopus art in Western prehistory: pottery vessels covered in octopus tentacles, indicating either ritual significance or deep aesthetic respect, possibly both. The Knossos Octopus Vase is the era’s signature object.
• Japanese cuisine and ritual — takoyaki, tako sashimi; the octopus also appears in Hokusai’s 1814 The Dream of the Fisherman’s Wife, which Western audiences have struggled with ever since (and which is, among other things, a meditation on octopus sentience as alien-erotic — pre-modern Japan willing to imagine cross-species intimacy with an animal recognized as a peer).

Across these traditions, the octopus is rarely just food. It is treated as an interlocutor — a being that meets the human gaze, sometimes adversarially, sometimes as a kind of cousin.

Practical — what octopus thinking gives the wiki

This wiki is being built around the principle that cognition is wider and stranger than the vertebrate cortex suggests. The octopus is the third-party witness.

• Mind doesn’t require a brain in the head. The octopus distributes most of its neurons into its arms, each acting semi-autonomously. Any assumption that cognition must be centralized in a single command center misses most of the design space biology actually uses.
• Embodied cognition is empirically real. The arms know. The skin senses. Decisions emerge from the whole system. For a venture building toward autonomous farms, robotic systems, distributed sensors — design from the octopus, not from the desktop computer.
• Convergence proves possibility. Complex flexible cognition arose independently at least twice on Earth — in vertebrates and in cephalopods. The octopus is reassurance that minds are not vanishingly rare; they are what biology does given enough time.

Spiritual / philosophical

Peter Godfrey-Smith’s Other Minds (2016) [7] argued that octopuses are the closest thing to encountering an alien intelligence we will ever experience without leaving the planet. The encounter changes how you think about what minds are.

If consciousness can have eight semi-independent loci in one body — each arm carrying out hunts the brain doesn’t direct moment to moment — then the question “where does the mind live” doesn’t have one answer. It has eight, or nine, or however many partial centers the body grew. The octopus suggests that mind is the kind of thing that spreads given a substrate.

The octopus is the biological proof that “what counts as a mind” is wider than the cortex.

Threats to the kin

• Climate change and [[ocean-acidification|ocean acidification]] are reducing octopus habitat and prey availability worldwide, even as species ranges shift.
• [[industrial-agriculture|Industrial farming]] of octopus — the first commercial octopus farm opened in Spain in 2024 — has triggered an unusually broad coalition of opposition, including from peer-reviewed scientific bodies citing the welfare evidence in this entry. Farming a creature documented to have individual personality, problem-solving, and possible dreams produces a moral category-error of a magnitude the food system hasn’t grappled with before.

Lenses still to grow

• Octopus behavior in genuinely wild settings (most research is on captive animals) — what does the species do when not surveilled?
• The octopus genome’s high RNA-editing rate, possibly a substrate for behavioral plasticity (Liscovitch-Brauer et al. 2017)
• Cuttlefish and squid as the cephalopod kin — even more sophisticated visual signaling, similar nervous-system architecture
• Indigenous knowledge systems on cephalopods — the existing scientific literature has only recently begun to engage these as primary sources

See also

Auto-generated from this entry’s typed relations: frontmatter, grouped by relation type so the editorial signal isn’t flattened.

• Instance of: [[cognitive-symbiosis]]
• Member of: [[animal]]
• Cousin of: [[slime-mold]]

Sources

[1] Hochner, B. (2012). “An embodied view of octopus neurobiology.” Current Biology, 22(20): R887–R892.

[2] Finn, J. K., Tregenza, T., & Norman, M. D. (2009). “Defensive tool use in a [[coconut|coconut]]-carrying octopus.” Current Biology, 19(23): R1069–R1070.

[3] Ramirez, M. D., & Oakley, T. H. (2015). “Eye-independent, light-activated chromatophore expansion (LACE) and expression of phototransduction genes in the skin of Octopus bimaculoides.” Journal of Experimental Biology, 218(10): 1513–1520.

[4] Anderson, R. C., Mather, J. A., Monette, M. Q., & Zimsen, S. R. M. (2010). “Octopuses (Enteroctopus dofleini) recognize individual humans.” Journal of Applied Animal Welfare Science, 13(3): 261–272.

[5] Mather, J. A., & Anderson, R. C. (1999). “Exploration, play, and habituation in octopuses (Octopus dofleini).” Journal of Comparative Psychology, 113(3): 333–338.

[6] Medeiros, S. L. de S., Paiva, M. M. M. de, Lopes, P. H., Blanco, W., Lima, F. D. de, Oliveira, J. B. C. de, Medeiros, I. G., Sequerra, E. B., Souza, S. de, Leite, T. S., & Ribeiro, S. (2021). “Cyclic alternation of quiet and active sleep states in the octopus.” iScience, 24(4): 102223.

[7] Godfrey-Smith, P. (2016). Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness. Farrar, Straus and Giroux.