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The Eightfold Way*: Octopus Intelligence

Writer's picture: Mishkat BhattacharyaMishkat Bhattacharya

This is a post along the lines of my interest in animal behavior. I have been fascinated by octopuses (octopi is not the correct plural) for a while. They seem to have high intelligence, but a different evolutionary model for it (e.g. a decentralized brain/nervous system) than humans.


There are lots of interesting things about octopuses, this short post will focus on a chosen few.


Basic facts:


i) What they are: An octopus is an invertebrate (i.e. no bones in its body, allowing for all kinds of escape art). It is a cephalopod (Greek for 'head-feet'), like a squid.


ii) Where they can be found: Deep as well as shallow salt water. An octopus can stay alive for about an hour outside of water. This allows it to escape from their tanks in an aquarium, often to find food in nearby fish tanks.


iii) Life span: 1-5 years. Octopuses breed once and die. Males die after injecting sperm into the female; females die after they hatch eggs and tend them. Mating can also result in cannibalism - the female eats the male. Octopuses goes through senescence before dying - not eating, moving little, showing signs of dementia.


iv) Social habits: Octopuses are mostly asocial. They are amazing at camouflage (this video is incredible too) due to the chromatophores (color-changing cells) under their skin.


I remember reading a study in which an octopus was placed in a swimming pool whose bottom was basically a computer screen which could be programmed to different patterns and designs. They found the octopus could change very quickly to match complex - even fractal - patterns on the floor bottom. An octopus releases ink to help get away from predators. This ink is pretty close to being indelible, and survives well even in old fossils.


Octopuses love curling up by themselves in a den. In the past, they were fished by simply lowering clay pots to the sea bottom, which they would enter and refuse to leave even when the pots were drawn up to the surface.


v) Physical strength and agility: The suction cups on their tentacles can apply enormous pressure. They have thousands of suckers on their arms and each one can lift about thirty pounds. The suckers also allow them to taste with their arms.


They do tire easily and they cannot move very fast for very long. Their blood is blue, and quite viscous, and they have three hearts.


vi) Venom: All octopuses are venomous. Maybe I should have put this up top. Only the blue-ringed octopus has venom deadly enough to kill a human being.


Intelligence:


i) Brain-to-body mass ratio: Octopuses have the highest ratio of all invertebrates and larger than many vertebrates. They have both short and long term memory.


ii) Tentacles: Are partially independent of the brain. An arm severed from an octopus can catch prey and send it to the (nonexistent) mouth. The octopus regrows the missing arm.


iii) Chromatophores: Octopuses indicate their mood by changing their color. E.g white for fear or relaxation, and black for aggression.


iv) Intelligence display: They can recognize humans (many octopus researchers have reported feeling being 'watched'). If they don't like you they can hose you with water (you have to wait a bit to see that in the video).


They have their own personalities. They can learn to get to food by unscrewing lids from jars, or calling humans by ringing a bell, or solving more complex puzzles. They also show the tendency to play with objects provided in their tanks. The rough agreement between researchers seems to be that the octopus's intelligence is comparable to that of a dog's.


Bonus Confession: Yes, I have eaten octopus. Not a favorite.


[1] The Soul of an Octopus by S. Montgomery

[2] Octopus by R. Schweid


*This is a reference to a famous cataloging scheme in particle physics, and also, of course to the number of arms an octopus has.

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