Recently a friend was informing me about the intelligence of octopuses (I have found that the use of ‘octopi’ is actually incorrect – unless you want to sound Latin). I then relayed this information to some other friends… two days later I was hit in quick succession by some visual and auditory references to octopus. The first was a video of the Mimic Octopus (featured below), the second was on the Twis podcast I was listening too. I was intrigued to say the least and after sending some emails around decided to make a more consolidated effort here – hopefully you find it interesting.


The Indonesian Mimic Octopus.
Firstly some facts from the CBC documentary “Aliens of the Deep Sea” to get you interested and set the atmosphere:
  • Octopus have three hearts and nine brains.
  • An octopus is more closely related to an oyster or a snail than to any other species of animal.
  • A female octopus dies once her young are ready to be born. This means that each generation of octopus learns about its world from scratch.
  • The octopus can change its skin colour, markings and texture at will and quickly. They can even take on the texture of the ocean floor. It is an intelligent shape shifter that can disguise itself in myriad ways.
  • An octopus knows exactly how big it is and will not attempt escape when confined if the door is too small.
Quite a number of these facts refer to intelligence or learning (I coloured these references blue). The above video talks about how it can shape-shift to scare away prey. Linking this to the fact that a baby octopus “learns about its world from scratch” implies it must watch and observe its environment, learning these defence tactics. Below I will retell the story about octopus learning that my friend passed onto me, the one which started this octopus escapade. But firstly another video of the Mimic Octopus (I found this guy really interesting and really wanted to go see one!).


Another video of the Indonesian Mimic Octopus.

Octopus Learning

I will start by recounting the story my friend told me which started this octopus escapade. The story refers to some research research by Fiorito and his colleagues who were investigating the observational learning in wild octopus vulgaris with a puzzle-box experiment. Their experiment/story goes/went something like this:

Researchers were looking into the ways octopus learnt. They sourced octopus from the local fisherman who would often catch them in their fishing nets. One such ‘control octopus’ is put into a tank were it retreats underneath a log; scared of its new surroundings. A clear acrylic puzzle containing a tasty crab is placed into an adjoining tank housing an octopus who has resided there for some time. The puzzle can be opened on several of the sides, each side requiring a different method. One side might require a cap to be screwed off, whilst another might be to be simply pulled off. The octopus in the adjoining tank is familiar with the puzzle and welcomes the easy meal swimming right up to the acrylic puzzle. As the octopus grapples with the puzzle the newly located octopus takes an interest, first watching from under the log and then coming out for a closer look. In fact, it soon presses up against the glass becoming visibly excited as the puzzle is solved and the tasty/poor crab is obtained. The tanks are then isolated using an opaque divider and the same puzzle is placed into the new octopus’s tank. The new octopus swims straight up to the puzzle and solves it in the same way it has just observed. The orientation of the puzzle did not have any effect, the new octopus would instantly isolate the side it knew how to open to seize its prize.

After some searching I found the documentary that included this experiment and have uploaded a video:


Observational learning exhibited by octopus vulgaris.

It turns out there has been interest in octopus learning for some time. The earliest paper appears to be Observational Learning in Octopus Vulgaris (Fiorito & Scotto 1992) where, similar to the above experiment, untrained octopuses observe a ‘demonstrator’. In this experiment two coloured balls where used: red and white. In one group the red ball was considered to be the ‘correct choice’ and when an octopus selected/attacked this colour they received a tasty piece of fish. If they selected the white ball they were punished by a small electric shock. In a second group these conditions where reversed.
The trained octopus where then used as demonstrators, whereby an untrained octopus in an adjacent tank observed, for four repetitions, the act of choosing the ‘correct’ ball. For each subsequent trial the untrained octopus increases its attention following the demonstrators movements with their eyes and even moving their heads. The now-trained octopus where then tested and (when a selection was made) conformed 91% of the time to what they had observed. This provided evidence that it was possible for invertebrates to demonstrate observational learning.Interestingly octopuses cannot actually see colours which is hard to believe when watching the way they camouflage into their surroundings (especially the colours demonstrated by the Mimic octopus in the videos above). One breathtaking possibility discovered by researchers of the Woods Hole Marine Biological Laboratory and University of Washington found that “the skin of the cuttlefish Sepia officinalis, a colour-changing cousin of octopuses, contains gene sequences usually expressed only in the light-sensing retina of the eye. In other words, cephalopods (octopuses, cuttlefish, and squid) might be able to see with their skin!”
There has been earlier evidence of the problem solving prowess of octopuses, for example Jacques Cousteau filmed an octopus opening a corked jar back in the 1950s. Even earlier (around the 200A.D.) the Roman natural historian Claudius Aelianus described octopuses, saying that the ‘mischief and craft can be plainly seen in the characteristics of this creature’.


Some footage by Jacques Cousteau. In particular: an octopus opening a corked jar.

More recently octopuses have been taught to go through mazes, exhibiting excellent short and long term memory. Captive octopuses are quite the escape artists and sometimes climb out of their tanks, crawl across the floor, and then climb up into another tank to eat a fish before returning back to their tank. Psychologist Jennifer Mather  has observed an octopus who had just returned to its home and was cleaning the front of the den with its arms. “Suddenly it jetted out directly to a small rock about [one or] two meters away, tucked it under its spread arms and jetted back. Going out three times more in different directions, it took up three more rocks and piled the resulting barrier in front of the entrance to its den. It held them in front with several arms and went to sleep” (see the similar video below). This didn’t look like random action, but suggested  foresight, planning, and even demonstrates tool-use.In another experiment when live Venerupis clams were ‘modified’  the octopuses’ intelligence and adaptability was also showcased. Wodinsky (1969) found that Octopus vulgaris eating Strombus, gastropods would “drill through the shell apex to poison and weaken the snails’ adductor muscles. When he coated this part of the shell with latex, they just pulled it off, then drilled as before. When he then put on aluminium, they simply drilled through the metal and shell, but when he coated it with impenetrable dental plastic they
drilled elsewhere on the shell, or pulled the snail out by sheer force.
They were intelligently adapting the penetration technique to the clam species presented and the situation in which they were placed.”Octopuses have also learnt to use “eye-hand” coordination, a skill they have not required in nature as touch makes more sense (pun intended) when exploring crevices. Gutnick and colleagues (2011) designed a task that requires a “visually guided reaching movement”. The octopus reach through to the end of a tube where three smaller tubes are located – one with a food reward. “Because the tubes were transparent, the octopus was able to see the food”. The octopus was only given a single chance, meaning it had to rely on its sight instead of probing around like they would normally do. The result showed that octopuses could learn to use sight to guide their arm straight to the correct inner tube.It is interesting to note that octopuses rely on monocular vision (i.e. favour one eye over the other). “Such lateralisation, corresponding to our right- and left-handedness, suggests specialisation in the brain’s hemispheres, which is believed to improve its efficiency.”
Furthermore, Mather and Anderson have published some controversial work that octopus individuals show distinct personality traits (a first for an invertebrate); and that some individuals even like to have fun. Presented a situation “one [octopus] might flee, but another might fight, or show curiosity”. Once octopus named Truman (names also suggest a personality) had taken a disliking to a particular volunteer: “Using his funnel, the siphon near the side of the head used to jet through the sea, Truman would shoot a soaking stream of salt water at this young woman whenever he got a chance. Later, she quit her volunteer position for college. But when she returned to visit several months later, Truman, who hadn’t squirted anyone in the meanwhile, took one look at her and instantly soaked her again.” So, “why does [personality] matter to the demonstration of intelligence? For one thing, personality overlays intelligence. Autistic children’s intelligence is often hard to measure because they don’t like people well enough to cooperate with the testers.””Anderson tested for ‘play’ by presenting eight giant Pacific octopuses with floating pill bottles in varying colours and textures twice a day for five days. Six octopuses examined the bottles and lost interest, but two blew them repeatedly into their tanks’ jets. One propelled a bottle at an angle so it circled the tank; the other shot it so it rebounded quickly—and on three occasions shot it back at least 20 times, as if it were bouncing a ball.”


Octopus blocking den entrance and Joan Boal expressing some scepticism.

Despite this seemingly intelligent/human behaviour, respected cephalopod researcher Jean Boal is questioning if the octopuses are really intelligent or if they are just demonstrating what we would consider intelligent behaviour. Maybe they are just exhibiting fixed complex behaviours? She, as well as others, have been unable to reproduce the observational learning results demonstrated by Fiorito.
Whatever is correct, it is best to treat octopuses humanely/kindly as they “very likely have the capacity for pain and suffering… perhaps even mental suffering.” “Ludovic Dickel, a neuroethologist at the University of Caen, found that cuttlefish raised in groups and in tanks with sand, rocks, and plastic seaweed grew faster, learned faster, and retained more of what they learned than those raised alone in bare tanks. Performance rose in animals transferred midway from impoverished to enriched conditions and declined in those transferred to solitary confinement.”

Short Lives and Communal Learning

The octopus mind and the human mind probably evolved for different
reasons:
“Humans, (like other vertebrates whose intelligence we recognize) are long-lived, social beings. Most scientists agree that an important event that drove the flowering of our intelligence was when our ancestors began to live in social groups. Decoding and developing the many subtle relationships among our fellows, and keeping track of these changing relationships over the course of a typical human lifespan.”
In contrast octopuses are neither long-lived and appear to be solitary, non-social creatures. “The natural lifespan of a giant Pacific octopus is only three [or four] years” and the longest living octopus, the Arctic octopus lives to only six years.
These fundamental differences are interesting, as, “according to the social theory of intelligence articulated by N. K. Humphrey and Jane Goodall, complex brains blossom in complex social settings; chimps and dolphins have to be smart to read the intentions of other chimps and dolphins. Moreover, such smarts arise in long-lived animals: Extended childhoods and parental instruction enable them to learn, and longevity justifies the investment in big brains.” Female octopuses tend their eggs, but once the tiny hatchlings come out into the world they die from starvation/exhaustion. “As cephalopod-respiration expert Ron O’Dor of Dalhousie University in Nova Scotia wonders, “Why would you bother to get so smart when you’re so short-lived?”
Jennifer Mather believes “the event driving the octopus toward intelligence was the loss of the ancestral shell”. This made octopuses more mobile allowing them to actively seek food, but also meant that they had limited protection from larger predators. To solve this problem they had to develop intelligence to camouflage and deceive potential threats.
There is however growing evidence that octopuses are communicating more with others of their species than researchers previously realised. “Cigliano found that California octopuses that were kept together quickly established hierarchies and avoided wasteful, dangerous confrontations; the weaker animals seemed to recognise and yield to the stronger ones, even when the latter were hidden in their dens.” Peter Godfrey-Smith has also seen two octopuses living just two feet apart for more than a week on his dives in Sydney Harbour, Australia. He has also visited a diver further down the coast who has found a group of octopuses living together and interacting.
Off the coast off the (Felix) Anton Dohrn Institute near Capri, octopus have also been observed to be living amongst other octopuses becoming more dominant in their environment; prey becoming predator. They have began to interact and observe each others behaviour, the younger octopuses possibly learning from those older. Could this be a quantum leap in the evolution of this species? An end to the vicious cycle of coming into the world with no adult to learn from? Perhaps the octopus’s horizons are expanding!

Nine Brains!

I was quite interested in the fact octopuses have nine brains. After some more research I found that octopuses have large nervous systems, centred around relatively large brains (which is in a doughnut shape around their oesophagus). It turns out that around three-fifths of octopus’s 500 million neurons (close to the number in a dog) are found in the arms themselves! These neuron clusters at the base of each arm are something akin to a brain.
This raises the question of whether the arms have something like minds of their own? Godfrey-Smith has studied consciousness in octopuses, and describes their minds as potentially an example of “distributed consciousness.” “Though the question is controversial, there is some observational evidence indicating that it could be so. When an octopus is in an unfamiliar tank with food in the middle, some arms seem to crowd into the corner seeking safety while others seem to pull the animal toward the food.” It seems the creature is literally of two minds about the situation.”
The octopuses have a central brain as well as concentrations of neurons at the base of each of their eight legs.
In another experiment the researchers killed a number of octopuses (which is sad – see European Union directive below) and then kept the removed arms in cold seawater for up to an hour (n.b. octopus can regrow their arms – but obviously not when they have been killed). They then took the arms, some of which were suspended, and other which were laid out on a flat surface and proceeded to pinch/prod the arms and also expose them to tap water and acid. All the arms regardless of the orientation coiled away from the stimulus source within one second.
In science terms, the arms exhibited reflex-withdraw to a noxious stimulus, without reference to the (main) brain. This supports the idea that octopus have nociceptors (neurons which respond to physical danger) in their arms. In humans these are located in the spinal chord meaning a severed arm would not respond to pain.
An octopus tentacle pulling it away from a petri dish with acid in it.
On a similar detached octopus arm note: “researchers who cut off an octopus’s arm discovered that not only does the arm crawl away on its own, but if the arm meets a food item, it seizes it-and tries to pass it to where the mouth would be if the arm were still connected to its body.”
Thankfully “this kind of scientific experiment probably won’t happen again any time soon. Because there is so much evidence for octopus intelligence, the European Union has issued a directive stating that no experiments may be done on octopuses (and possibly other cephalopods like squid) that cause them unnecessary pain or distress. And I think we can all agree that having your arms severed and then tortured is therefore off the list.”

Fine:

Hopefully you found octopus as interesting as I have.  For the last few days I spent every spare moment researching and compiling this information. Below are links/references you might want to look at if your appetite is not fully sated.
Update 19th June 2016 – Just saw this paper:

References, Further Reading & Investigation:

Websites/Articles:

Pod Casts:

Documentaries:

Papers:

  • Fiorito, G., & Scotto, P. (1992). Observational learning in Octopus vulgaris. Science, 256(5056), 545-547. [link]
  • Gutnick, T., Byrne, R. A., Hochner, B., & Kuba, M. (2011).
    Octopus vulgaris uses visual information to determine the location of its arm. Current biology, 21(6), 460-462. [link]
  • Hague, T., Florini, M., & Andrews, P. L. (2013). Preliminary in
    vitro functional evidence for reflex responses to noxious stimuli in the
    arms of Octopus vulgaris. Journal of Experimental Marine Biology and Ecology, 447, 100-105. [link]
  • + MANY MORE!
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