Simple Solution To Octopus Arm-entanglement Mystery

[PiSquare]

Scientists attempted for quite some time to solve the mystery of how an octopus avoids being tangled up in its own suckers as its brain is unaware of what the eight arms are doings. The brain of a human maps out the path to the limbs of the body and uses this mapping method to coordinate the parts, but an octopus does not have such a method. The arms have infinite freedom of movement, making a mapping system virtually impossible. Yet, the many suckers on each arm stick to almost anything but the octopus itself. 

 

The answer is unbelievably simple and proves once again that we need to keep our thinking simple. Wait for it ... the answer is ... a chemical produced by the skin of the octopus prevents its suckers from latching onto each other! Read the full article here.

[CraigD]

How elegant! and bearing on a subject I much enjoy, if for no other reason than its names rolls elegantly off the tongue: proprioception and, sometimes, kinesthesia.

 

I found the (short) paper behind the linked International Business Times article, “Nesher et al., Self-Recognition Mechanism between Skin and Suckers Prevents Octopus Arms from Interfering with Each Other, Current Biology (2014)” a this free Cell article.

 

The research is what I’d call preliminary to intermediate – Nir Nesher and his 3 coauthors have experimented with octopi, amputated (which they term “decerabrated”) tentacles, and various skinned and ground-up-in-solvent, but not gotten to the underlying microanatomy and chemistry of the organs and molecules responsible for the title self-recognition mechanism.

 

Interestingly, the paper notes that, like human reflexes, the mechanism can be intentionally “overridden” by the octopus, and that when they're exerting a lot of intentional control over their tentacles, they “simplify” their movement – analogous again to human proprioception and kinetics, and reminding me of an observation by John Lilly that some complicated movement tasks, such as skiing or driving, can fail if one attempts to intentionally control them too much. Octopi appear to rely on thoughtlessly “going with the flow” even more than humans do, though we human are still arguably the best at the most demanding movement tasks of this kind, witness by the fact that no other animal has demonstrated the ability to learn complicated “flowing” motion tasks like free-style skateboard, or pilot an light airplane.

 

After reading the article, I realized I’d long assumed that octopi proprioception was based entirely, as its believe to be in humans, on specialized position-sensing nerves and reflex and brain pathways. I strongly suspect that octopi (which are surprising intelligent for invertebrates, being described by some experts as similar in intelligence to dogs) have vertebrate-like proprioception systems – witnessed by their ability to remember and mimic the shape of inanimate objects, and in some species, other animals. I’m curious if researchers have performed key human perception experiments, such as the rubber hand illusion with octopi?

[Eclogite]

 though we human are still arguably the best at the most demanding movement tasks of this kind, witness by the fact that no other animal has demonstrated the ability to learn complicated “flowing” motion tasks like free-style skateboard,

This may correlate with the absence of any animals that wear baseballs caps backwards and thus may actually be indicative of superior intelligence.

[PiSquare]

 I strongly suspect that octopi (which are surprising intelligent for invertebrates, being described by some experts as similar in intelligence to dogs) have vertebrate-like proprioception systems – witnessed by their ability to remember and mimic the shape of inanimate objects, and in some species, other animals.

 

Now you made me curious. Have you done research on the brain and central nervous system of an octopus? Roughly two-thirds of neurons in an octopus lie in the nervous system of the arms, which is thought to control some aspects of movement with little input from the brain (see this blog). It thus seems that octopi display both conscious and unconscious proprioception, correct?

[CraigD]

Have you done research on the brain and central nervous system of an octopus? Roughly two-thirds of neurons in an octopus lie in the nervous system of the arms, which is thought to control some aspects of movement with little input from the brain (see this blog).

I’ve not done nearly the research that the psych and pharmacology student “the Cephalover” has as shown in his blog, but recognize some of the papers and research mentioned, and had a basic understanding of their weird (compared to vertebrate) neuroanatomy.

 

Wrapped as it is around the esophagus, much of the octopus brain reminds me of a hyper-developed mammalian vagus nerve, except that while the mammal vagus nerve manages not only gastrointestinal movement, but also the heart and larynx, cephalopods have no larynx, and have 3 strange little hearts well removed from their brain. Of the rest of the octopus brain, the biggest lobes are next to its eyes and appear mostly dedicated to vision – they look almost grafted on, as if a gullet grew a pair of eyes, which isn’t, I think, an unhelpful perspective on octopus anatomy.

 

I find this image, which Cephalover linked to, helpful:

 

What’s I find most amazing about octopi is that, despite their tiny brains, they are able to learn in ways one might expect only large-brained animals could, most remarkably by watching other octopi perform “unnatural” tasks, such as preferring one color ball to another, which was discovered ca 1995 and written about in papers such as the one Cephalover cites in this blog post.

 

It thus seems that octopi display both conscious and unconscious proprioception, correct?

Yes, in essence, but I’d avoid using the term “conscious” in favor of one like “intentional”, or “under the control of a central brain”, because consciousness is so much associated with the idea of having an mental self-model – that Hofstadter calls “the mind’s ‘I’”.

 

For all their amazing mental abilities, I’m conflicted reluctant to conclude that more than a handful of animals, all of them vertebrates and only a few non-mammals, have consciousness of this kind. Though it’s far from perfect and definitive, the mirror test is my favorite test for consciousness. Only the great apes (which include us humans), elephants, some cetaceans (dolphins and whales), and one species of bird has been show conclusively to have passed this test.

 

My conflict about the possibility of octopus consciousness comes from their ability to learn from watching other octopi. Such learning implies that they have an mental “other model” that allows an individual octopus to relate seeing another octopus do something to doing it themself. While such learning is seen in many animals that can’t pass the mirror test (housecats, for example) having an other-model seems to me a step in the direction of having a mirror-test enabling self-model.

 

From the reading I did for this thread, I see that questions like this aren’t just of academic interest, because some regulators believe that octopi and other cephalopods should be reclassified from their current status as animals that can be experimented on without ethical considerations (eg: operated on surgically without anesthesia) to ones what feel fear and pain, and thus should be ethically protected and humanely treated.

[PiSquare]

Absolutely fascinating, Craig! I am amazed by how small the stomach of an octopus is, and the heart (systemic and branchial).

 

I agree with you, the word "conscious" was not the best term to use in this instance. I always have flashes of evolution in my mind when seeing a picture/video or reading of octopi. Might it be that this creature would one day (in a few million years) 'develop' a consciousness, especially because of its brain capacity?

 

The information you gave on the mirror test provided for thought-provoking reading. I must admit, I tend to agree (in some instances) that this test might be of lesser value when applied to animals who rely primarily on senses other than vision. However, your conflict about octopi having a consciousness or not should in my opinion be taken seriously and researched further - you made a valid point. Have you thought of a possible "other model" yet? 

Edited May 19, 2014 by PiSquare

[Gregb]

The Octopus is seriously one of the most amazing creatures on earth!

[PiSquare]

I agree! If you take a close look at the figure Craig posted elsewhere in this thread, all of the the organs of the octopus are in (what I thought was) its head. I now realize its 'head' is actually the entire body. And the organs seem so out of place, scattered everywhere, with the hearth below the stomach.

 

It is also now easier to see how its arms could be able to to move without using too much brain power. 

[Eclogite]

From the reading I did for this thread, I see that questions like this aren’t just of academic interest, because some regulators believe that octopi and other cephalopods should be reclassified from their current status as animals that can be experimented on without ethical considerations (eg: operated on surgically without anesthesia) to ones what feel fear and pain, and thus should be ethically protected and humanely treated.

I have had a long standing agreement with all members of the Cephalapoda: I don't eat them and they don't eat me. So far this has worked out well for both of us.

[Buffy]

I have had a long standing agreement with all members of the Cephalapoda: I don't eat them and they don't eat me. So far this has worked out well for both of us.

 

Ever since I saw 20,000 Leagues Under the Sea I have had a deathly fear of squid and have enjoyed eating them to let them know who's on top of the food chain.

 

 

Blow me down and pick me up, she swapped me for a trout! :phones:

Buffy

[Foghorn]

Many squid might enjoy eating YOU as plentiful protein is essential for brains.

 

The original OP made it sound to me as if squids, or sqidlike families had no control over their tentacles, thus making them unable to eat. Surely I am wrong.

 

I doubt anybody here is able to correctly speak to a creatures conscious as they cannot correctly speak to their own.

 

A dog who crosses a continent to rejoin with it's family, is it not conscious?

 

A porpoise that nose butts sharks away from a helpless human diver, is it not conscious?

 

I submit, that when we can understand consciousness, we might be more able to recognize it in others.

[Moontanman]

Having raised many octopus from tiny babies through adulthood I think a pretty good case can be made they are conscious. They have nine brains, something the above schematic fails to show. It's absolutely awesome to see how octopus learn, watch them try to get your attention just for the attention, see them do all sorts of wild things that seem at least to show intelligence even though their lives are very short, most less than a year. 

 

The neatest thing is how seriously they take being given a gift of odd object, the way they fondle the objects and how the texture of the objects affect them and how pissed off they get when you give them ping pong balls... 

[CraigD]

The original OP made it sound to me as if squids, or sqidlike families had no control over their tentacles, thus making them unable to eat. Surely I am wrong.

Yes, you are wrong.

 

The article, and subsequent posts, note that octopi (Nesher et al’s research is with common octopi, not squid, though the various cephalopod species are evolutionarily closely related and anatomically similar, so the research likely applies to many of them) appear to be unaware of what their tentacles are doing, but can exert control over them as needed.

 

This raises the question of how an octopus’ tentacles, which are covered with gripping suckers, avoid gripping one another, yet will grip a severed tentacle of another octopus. Nesher’s research suggests that chemical signals cause the suckers to “recognize” the octopus’ skin, and avoid grasping it.

 

I doubt anybody here is able to correctly speak to a creatures conscious as they cannot correctly speak to their own.

“Consciousness” (the noun form of the adjective “couscious”) is a troublesome term, because it is applied to many different concepts and phenomena. From your questions that follow, I think you’re using it in the sense that people like Hofstadter and Dennett do in books like The Mind's I and Consciousness Explained.

 

Perhaps the best known objective, yes-no test for consciousness of this kind is the “mirror test”. It’s been performed, giving farily certain answers for the animals about which you ask and relatives of them:

A dog who crosses a continent to rejoin with it's family, is it not conscious?

According to the mirror test, dogs are not conscious.

A porpoise that nose butts sharks away from a helpless human diver, is it not conscious?

According to the mirror test, bottlenose dolphins (physically larger, more intelligent relatives of propoises) are conscious. I don’t know if porpoises have been tested, of have a confident guess if they would pass or not.

 

I submit, that when we can understand consciousness, we might be more able to recognize it in others.

My take on the long and complicated history of attempting to define and understand consciousness is similar to Hofstadter’s: that self-modeling and planning is involved, but that symbolic reasoning and learning may be similarly important attributes to the “consciousness” attribute as measured by the mirror test. Understanding only that attribute will not, I think, be sufficient to understand well the human and other animal psyches.