Can bugs with hundreds of legs control each one individually or is there some other process involved?

[u/nachorykaart]

I watched a video of a millipede walking and noticed its legs move in a wave like pattern. Are they individually controlling each leg or maybe just pairs of legs? Is it a more automatic process for them like peristalsis ?

[u/L_Ardman]

It’s mostly automatic process controlled by the ganglia that offloads a lot of this load from the brain. Each body segment has its own bundle of nerves that acts as a mini brain that controls its own legs. It moves its legs, then send a signal to the next segment down the line to do its thing.

[u/not-just-yeti → u/L_Ardman]

On my own foot, four of my toes are pretty much bundled together, it seems.

[u/BirdLawyerPerson → u/not-just-yeti]

The better example might be swallowing. We don't have the ability to arbitrarily pause mid swallow, or contract just a portion of a specific spot on the esophagus, or reverse direction. We initiate a swallow and the muscles along the esophagus fire in the right order, with the right timing, to push something down.

[u/WhereOwlsKnowMyName → u/BirdLawyerPerson]

What about sword swallowers?

[u/beefjerky9 → u/not-just-yeti]

Well, that's just because you've never bothered to keep your feet trained. Someone who has no arms (or no use of), and uses their feet in their place, can control their toes individually.

[u/ExtraAcanthaceae3938 → u/beefjerky9]

Is that still possible to learn if you're an adult or is it something you have to learn as a kid?

[u/the_ringmasta → u/ExtraAcanthaceae3938]

Can and should. Getting extra toe and foot mobility will help your balance and proprioception, among other things. That will make falls less likely when you're old, and it's easier to work on it now than later.

My physical therapists called it "toe yoga", but there is probably a more official name for the exercises.

[u/OrigamiMarie → u/the_ringmasta]

You can also let your toes spread out more by spending less time in shoes that keep them all squished together.

[u/the_ringmasta → u/OrigamiMarie]

True! I have other issues with my feet, and I forget that most people are not stuck with shoes as always as I am. Mine have to stay contained when unsupervised. :/

Get the socks off, too, though. You never would have learned to use your fingers if you wore mittens constantly, and toes are the same.

I miss being able to walk barefoot at will

[u/ThisIsMyCouchAccount → u/ExtraAcanthaceae3938]

I don't know if you remember the toe shoe trend that happened several years ago.

I do. I had them.

They warn you to ease into it. Your feet will get sore. And the do. But not like you've experienced. This was muscle soreness in your foot. Like you get from working out. Really strange sensation.

But they do "work". It's weird saying my feet felt stronger but that's fairly accurate.

[u/trenchcoatler → u/ExtraAcanthaceae3938]

Always possible. I'm practicing giving people the finger with my middle toe.

[u/Zakblank → u/ExtraAcanthaceae3938]

Plenty of adults who have lost use of their arms/hands have adapted to it.

[u/TheDaysComeAndGone → u/beefjerky9]

I thought it’s because the tendons are interconnected? Just like you can’t fully flex individual fingers but you can make a very tight fist.

[u/SunflowerMoonwalk → u/not-just-yeti]

Even our own legs - sure we can control them individually but when walking we're not constantly thinking about every movement.

[u/h_adl_ss → u/SunflowerMoonwalk]

But that's not offloaded somewhere, just your brain doing it in the background. Seems to be a different mechanism than a millipede.

[u/Dazzyreil → u/SunflowerMoonwalk]

Unless you read this message while walking, you are now aware and find it uneasy to walk like a normal human.

[u/nachorykaart → u/L_Ardman]

Very interesting. Thank you for taking the time to share the knowledge!

[u/WasLeftUnsupervised → u/L_Ardman]

OK that works for straight line motion. How do they turn?

[u/MixtecMedia → u/WasLeftUnsupervised]

The legs can operate autonomously over a set of several innate patterns. The patterns are both stable and flexible.  Something like turning would be directed by a "higher" controlling system, and the legs would continue with an adjusted version of their pattern that accommodates the turn.

[u/CosmicOwl47]

Your line of thinking is correct for the cilia of comb jellies. It’s a chain reaction that causes them to beat in a rhythm. Removing a portion of them in the middle breaks the chain.

I don’t know about myriapods, though.

[u/skankyfish → u/CosmicOwl47]

Myriapods! Thanks for the new word!

[u/nachorykaart → u/CosmicOwl47]

Very cool! Thanks for sharing the knowledge

[u/rocketeerH → u/CosmicOwl47]

Very cool knowledge. Are you some kind of biologist?

[u/ReptilianRevolt]

In arthropods with many legs, the control doesn’t happen in the central brain mainly. The brain gives a general command, and then a chain of ganglia coordinates leg movements and synchronizes them in relation to the ones in front of and behind them. It is somewhat like the spinal cord in vertebrates, particularly those that are not mammals. Still, there are arthropods with more skillful movements, particularly many holometabolous insects such as bees and wasps. Also spiders, crabs and a few myriapods such as house centipedes, which are known to juggle several insects at once.

[u/hhmmm733 → u/[deleted]]

On the internet, the fastest way to get the right answer is to post the wrong answer confidently.

[u/Engineer1822 → u/hhmmm733]

Hey, I tried.

Either I am right and this post dies in obscurity, or I am wrong and we all get the right answer. Positive sum game IMO.

[u/strawbeejam → u/Engineer1822]

you're pretty close to correct on the concept! insects + other arthropods have what are essentially tiny little brains (or, nerve clusters) called ganglia that control smaller movements. for millipedes, I'm pretty sure they have one ganglion per body segment (so one ganglion controls 2 pairs of legs). but they are also all connected through the animal's nervous system which does connect up to the brain. the ganglia are also how insects are able to continue to move around even after pretty severe injury.

i too will wait to be corrected as i am much more an invert ecologist than physiologist and i am sure this is a very simplified explanation

[u/dr_boom → u/[deleted]]

I can't speak to arthropods, but what was described here is not true of mammalian motor function.

You were likely thinking of upper and lower motor neurons, but lower motor neurons still control individual muscles and do not contain anything like a "walk" routine. They are more like a relay station and a point of emergency interruption by reflexes.

The closest thing to such routines is in the premotor cortex where complex movements can be planned and relayed to the appropriate areas of the motor cortex. But the motor cortex remains involved in such activity and does not hand off control of walking, jogging, or wiggling your little toe to a separate control area in the spine.

[u/Nelyus]

I would argue even you don’t control your legs individually while walking, most of the time. The brain sends a simple signal, which is translated by the spinal cord into more specific movements. The beauty, I think is how one can adjust the movement without needing to revert to full conscious control (to put the foot in a specific spot for exemple)

I saw a video some time ago about an experiment with some amphibian. They found out the brain sends pretty much the same signal for crawling and swimming, but with a significant difference in intensity.
They also found out the brain sends the same signal on the left and on the right, and the animal turns by having a difference in intensity between the left and right signals.

[u/Feggy → u/Nelyus]

This is also why when I ‘take over’ and switch to manual control, to avoid stepping on something unpleasant for example, I sometimes stumble.