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Tardigrades walk like insects 500k times their size

arstechnica.com

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Re: Tardigrades walk like insects 500k times their size

#11

Post by jcims »

crehn wrote: post #9
jcims wrote: post #7

With a few minutes of googling the only reference i can find says that Tardigrades have approximately 200 neurons in their brains [1] and their dry weight is on the order of one microgram [2]. They also have a lower count of synaptic connections (from the same paper): >Thus, miniaturisation of the tardigrade nervous system is achieved largely by reducing cell numbers, neuropil branches and the number of synaptic conn…

For contrast, ants have around a quarter million neurons.

We have mud dauber wasps around the house. I can't find a good reference for neuron count...the only one I see is for super tiny parasitic wasps which I can't imagine is accurate. Lets assume they are on the order of honey bees at 500k-1M neurons.

This past fall I saw one on the ceiling of my front porch. It had a rear leg pinched between the soffit and the edge of a can light. It was pretty obviously struggling, pulling away with its remaining legs and every now and then buzzing its wings. It was interesting but kind of a dumb 'more powah' response that could be the result of a biological integrator of some form.

I then saw one of the most remarkable things that I've personally witnessed in nature. Another wasp of the same type was randomly flying by, about 6" below the level of the ceiling and along a path that would have brought it no closer than a foot away from the stuck wasp. After flying past the stuck wasp, it took a hard right, circled around and landed near the stuck one. It then proceeded to walk up, grab the stuck ankle (?) of the other wasp and help it tug. They both worked on it for a few seconds, broke the first wasp free (not sure if the foot was still intact), then they both flew away in different directions.

I can build a mental model of a biological automaton lacing together finely tuned feedback loops that cause it to 'act' in a way that supports itself. Extending that to a point where it appears to identify, empathize, re-plan, solve a physical problem then resume prior plan starts to stretch my ability to imagine without some kind of subjective consciousness backing it all.

Re: Tardigrades walk like insects 500k times their size

#12

Post by est31 »

jcims wrote: post #11
crehn wrote: post #9

Earlier quoted context omitted.

For contrast, ants have around a quarter million neurons.

We have mud dauber wasps around the house. I can't find a good reference for neuron count...the only one I see is for super tiny parasitic wasps which I can't imagine is accurate. Lets assume they are on the order of honey bees at 500k-1M neurons. This past fall I saw one on the ceiling of my front porch. It had a rear leg pinched between the soffit and the edge of a can light. It was pretty obviously struggling, pul…

> I can't find a good reference for neuron count

https://doi.org/10.1371/journal.pone.0059090

    DNA labelling and analyses of confocal z-series reveal that the brain of Macrobiotus cf. harmsworthi contains ∼200 nuclei that are arranged in a bilaterally symmetric pattern (Figure 2D and Figure S1). Since some of these nuclei are likely to be from non-neuronal cell types, such as glia cells, the tardigrade brain might contain fewer than 200 neurons.
Some more reading:

Martin et al. "The nervous and visual systems of onychophorans and tardigrades: learning about arthropod evolution from their closest relatives": https://bib-pubdb1.desy.de/record/401705/files/Martin_et_al....

Mayer et al. "Selective neuronal staining in tardigrades and onychophorans provides insights into the evolution of segmental ganglia in panarthropods": https://doi.org/10.1186/1471-2148-13-230

Also note that tartigrades apparently have a constant number of cells throughout their life, so instead of increasing the cell count, they just increase cell size. The cells can have increased complexity anyways. All it really means that the nervous system has about 200 nuclei. Also don't forget that even single celled organisms are capable of the classical behaviours like hunting for food, running away from predators, forming colonies (e.g. bacteria), etc.

Re: Tardigrades walk like insects 500k times their size

#13

Post by jer0me »

jcims wrote: post #7

With a few minutes of googling the only reference i can find says that Tardigrades have approximately 200 neurons in their brains [1] and their dry weight is on the order of one microgram [2]. They also have a lower count of synaptic connections (from the same paper): >Thus, miniaturisation of the tardigrade nervous system is achieved largely by reducing cell numbers, neuropil branches and the number of synaptic conn…

Though the ant example may be more interesting, humans have ~86 billion neurons.

Re: Tardigrades walk like insects 500k times their size

#14

Post by ad404b8a372f2b9 »

est31 wrote: post #12
jcims wrote: post #11

Earlier quoted context omitted.

We have mud dauber wasps around the house. I can't find a good reference for neuron count...the only one I see is for super tiny parasitic wasps which I can't imagine is accurate. Lets assume they are on the order of honey bees at 500k-1M neurons. This past fall I saw one on the ceiling of my front porch. It had a rear leg pinched between the soffit and the edge of a can light. It was pretty obviously struggling, pul…

> I can't find a good reference for neuron count https://doi.org/10.1371/journal.pone.0059090 DNA labelling and analyses of confocal z-series reveal that the brain of Macrobiotus cf. harmsworthi contains ∼200 nuclei that are arranged in a bilaterally symmetric pattern (Figure 2D and Figure S1). Since some of these nuclei are likely to be from non-neuronal cell types, such as glia cells, the tardigrade brain might con…

I'm pretty sure he was referring to the neuron count of the wasp.

Re: Tardigrades walk like insects 500k times their size

#15

Post by steve_adams_86 »

tiahura wrote: post #4

“The team was surprised to note that the water bears did not have distinct gaits for each speed, like horses as they transition from a walk to a gallop. Rather, their locomotion closely resembled that of insects and arthropods, scurrying along faster and faster with no change to the basic step pattern.” So they expected them to walk like horses and not insects? That seems odd.

I don’t know if it was an expectation so much as an observation which was then put into comparison to help explain it.

Re: Tardigrades walk like insects 500k times their size

#16

Post by fleddr »

jcims wrote: post #7

With a few minutes of googling the only reference i can find says that Tardigrades have approximately 200 neurons in their brains [1] and their dry weight is on the order of one microgram [2]. They also have a lower count of synaptic connections (from the same paper): >Thus, miniaturisation of the tardigrade nervous system is achieved largely by reducing cell numbers, neuropil branches and the number of synaptic conn…

I don't know the technical answer to your question but I do think that us humans have continuously underestimated the complexity and intelligence (in the broadest sense) of animals.

First, we see them as emotionless objects. Then we acknowledge that some animals seem quite smart, such as dolphins, dogs, pigs and cows, and of course other primates.

Then we discover that far more animals have complex systems to communicate by language, signs or color, have advanced courtship rituals and actual emotions, such as an elephant mourning.

And still we keep getting it wrong. Recently it was discovered that tiny earth worms, considered some of the "dumbest" and most primitive life forms, show complex behavior and have actual learning ability. For example, they drag leaves into their underground "den" to feed on them and over time learn which way is the correct way to drag the leaf, as the other way would block the den. That's a stunning interaction for such a simple creature.

Because it isn't a simple creature. Nothing is.

Re: Tardigrades walk like insects 500k times their size

#17

Post by throwamon »

jbotz wrote: post #8
1024core wrote: post #6

> "Other times, they’d see something they like and run towards it.” Can tardigrades really "see" in the traditional sense? Can they make out shapes, etc.? Do they have photo receptors plugged into the brain?

They can't "really see"... they have eyespots with just a handful of light-sensitive cells and no lenses, so it's just gradients of light and dark. But they have other senses and I think the word "see" was metaphorical here, meaning they sensed the presence of an attractive stimulus. In some ways the real meaning of "see" doesn't depend on optics, you see?

According to a video from another comment, each eyespot is a single cell.

https://www.youtube.com/watch?v=kux1j1ccsgg

Re: Tardigrades walk like insects 500k times their size

#18

Post by est31 »

ad404b8a372f2b9 wrote: post #14
est31 wrote: post #12

Earlier quoted context omitted.

> I can't find a good reference for neuron count https://doi.org/10.1371/journal.pone.0059090 DNA labelling and analyses of confocal z-series reveal that the brain of Macrobiotus cf. harmsworthi contains ∼200 nuclei that are arranged in a bilaterally symmetric pattern (Figure 2D and Figure S1). Since some of these nuclei are likely to be from non-neuronal cell types, such as glia cells, the tardigrade brain might con…

I'm pretty sure he was referring to the neuron count of the wasp.

Oh right, good point.

Re: Tardigrades walk like insects 500k times their size

#19

Post by abletonlive »

fleddr wrote: post #16
jcims wrote: post #7

With a few minutes of googling the only reference i can find says that Tardigrades have approximately 200 neurons in their brains [1] and their dry weight is on the order of one microgram [2]. They also have a lower count of synaptic connections (from the same paper): >Thus, miniaturisation of the tardigrade nervous system is achieved largely by reducing cell numbers, neuropil branches and the number of synaptic conn…

I don't know the technical answer to your question but I do think that us humans have continuously underestimated the complexity and intelligence (in the broadest sense) of animals. First, we see them as emotionless objects. Then we acknowledge that some animals seem quite smart, such as dolphins, dogs, pigs and cows, and of course other primates. Then we discover that far more animals have complex systems to communi…

Define "we". Because the smartest people I know are the ones most likely to underestimate as you've described and look down upon people that anthropomorphize. Further, it seems to me that the smartest people I know fall prey to reductionism when it comes to the subject of intelligence or philosophy in general.

Re: Tardigrades walk like insects 500k times their size

#20

Post by snidane »

jcims wrote: post #7

With a few minutes of googling the only reference i can find says that Tardigrades have approximately 200 neurons in their brains [1] and their dry weight is on the order of one microgram [2]. They also have a lower count of synaptic connections (from the same paper): >Thus, miniaturisation of the tardigrade nervous system is achieved largely by reducing cell numbers, neuropil branches and the number of synaptic conn…

200 neurons, yet still more AI complete than any concocted deep learning attempt with way more of so called "neurons".
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