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strengr t1_iv9x1jp wrote

The accepted theories is that because arachnids can spin both sticky and non-sticky webs, the spider knows where to walk so it doesn't stick to the web. Similarly a builder will know where to walk so their feet don't go through the drywall.

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BioTechproject t1_iva0utu wrote

Well, for the most part because they can spin different kinds of strings, depending on what the purpose of them is (sticky/non-sticky in this case)

They also have oils on their feet that they can secrete in order to un-stuck themselves

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Shadowwynd t1_iva4oia wrote

The spiders spin nonstick thread like scaffolding, then spin sticky thread and attach it the scaffold thread as a back and forth net. The spiders walk along the scaffold threads and not on the sticky trap parts.

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BDT81 t1_ivaeewp wrote

It depends on the species. Most ord-weavers though don't use sticky webbing. It'll adhere to a surface and dry quickly, but the insect will become entangled because it blunders into the net as opposed to the spider carefully climbing through it. The spider then has to wrap a fresh cocoon before its meal escapes.

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petdance t1_ivaxzl4 wrote

Replying to Shadowwynd (#456,258)

Do we know how they manage to produce both sticky and non-sticky? Is the base thread the same, but sometimes secrets sticky stuff along with it? Or are they two different types of thread?

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Docxx214 t1_ivb58iw wrote

Spiders can have up to 7 different types of spider silk, for all sorts of different purposes. Each silk has a different protein structure or composition of different protein strands.

Some of that silk can be considered 'sticky' which is the stuff designed to catch prey. When walking around their web they will avoid the sticky stuff but when they do have to interact with the sticky silk they will use little claws on the end of their feed called tarsal claws which help them manipulate the silk.

You might be asking how they stick to the non-sticky silk or anything for that matter. This is interesting and relates to physics. They use Van der Waals forces which is a weak attraction between atoms. The hairs on the pads of the feet are exceptionally dense, they have hairs, upon hairs, upon hairs which give them millions of points of contact for each foot. The strength of attraction for each hair is exceptionally low but with all of them combined it gives the spider the grip to carry about 170 times its own body weight.

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ramta_jogi_oye_hoye t1_ivb5hmj wrote

I have seen this in a video. The spider tip toes all over his web. Also, he is aware of which portions are non sticky. The web is just a bunch of booby traps; the spider just knows what to expect and when/where!

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Docxx214 t1_ivb5umc wrote

Replying to petdance (#457,440)

Different amino acid structure in the silk produces different types of silk with different properties. Sometimes the spider will manipulate the silk differently out of its spigots to suit its purpose. Spider silk is incredible stuff.

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Jertob t1_ivbt0e5 wrote

Replying to Docxx214 (#457,761)

The fact their little brains can know which type of thread to spin depending on the purpose is insane. I just don't get how genetics can randomly and efficiently arise to perform functionality that you would think needs an understanding of physics to accomplish. As if the DNA itself understand physics. Just don't get it.

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guyonahorse t1_ivbwc8y wrote

Replying to Jertob (#458,879)

That's the neat part, you don't need to understand physics to take advantage of it.

There are ways to use random numbers to solve problems you don't know the answer to. Think of trying to make a better paper airplane, you can start with randomly folded pieces of paper and throw them. Then you take the "best 10" and then randomly tweak those and repeat.

Eventually you'll have a fairly good paper airplane without any knowledge of aerodynamics.

Edit: I left out some parts, but people got the idea. When you take the "best 10" you likely will also remove the "worst 10" and then duplicate the top 10 (possibly not modifying the duplicates, etc). There are many ways to vary this, but it was meant as an example of how you don't need to understand physics to solve a physics problem.

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Training_Ad_2086 t1_ivbx8j5 wrote

Replying to Jertob (#458,879)

That's basically a billion year of trial and error before we arrived to the first spider.

All of life and evolution is basically trial and error by nature until something sticks. It happens on all sides, the predator , the prey and environment.

It's still happening right now.

A few hundred millions of years from now we'll have humans that unrecognizable from what we consider humans today

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ivan_drago27 t1_ivbxfui wrote

Replying to Jertob (#458,879)

Iteration. Spiders did not suddenly arise in the state that they exist today. Keep in mind, mutation drives evolution and is random in nature; but this does not mean that evolution is random. A random mutation generates a new physiology or behaviour, and if said behaviour lends its self to said organism reaching reproductive age and succeeding it will proliferate. Evolution is not forward thinking, it can not predict what will be successful in the future. While the sum of the parts seems incredibly complex and mind boggling, as you pointed out, in iteration, over the course of hundreds of millions of years, it becomes more clear.

Take for example, convergent evolution, wherein two species share a common trait, but do not have common ancestry. Sharks and Dolphins are no more related than Sharks and Dogs (maybe not technically true but for the sake of this point it is valid), yet due to their similar physiology many would assume them to have some shared ancestry. Rather, at some point in their respective lineage, each organism was very different, and yet through similar evolutionary pressures they both ultimately ended up with similar physiologies.

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Docxx214 t1_ivc88x0 wrote

Replying to Jertob (#458,879)

I won't repeat what the other comments have said because they're correct about how evolution works. Although I will say it appears that mutations might not be as random as previously thought and then, of course, you throw epigenetics into the mix and it goes to show that we really still have a lot to learn about how evolution and its mechanics work.

My response to OPs question was probably a little bit anthropomorphic in nature but I found sometimes it's easier that way when communicating scientific stuff.

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popbottle159 t1_ivcp4ed wrote

Replying to MrRumfoord (#459,707)

Look up the side view of a stealth bomber and a diving falcon. One is human calculations and wind tunnels. The other is pure nature streamlining the best way for high speed flight.

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CodingLazily t1_ivcphzs wrote

Replying to MrRumfoord (#459,707)

I don't know about paper airplanes, but here's an antenna that is the result of a supercomputer running simulations with an evolutionary algorithm.

https://en.wikipedia.org/wiki/Evolved_antenna

​

Evolutionary algorithms are basically the same as evolution, but to summarize evolutionary algorithms for those who aren't CS majors: First, you generate a random population of candidates. You test each candidate for fitness to see which ones best meet the criteria and survive the generation (in this case by simulating the antenna.) You take the top few candidates and populate a new generation with a few thousand descendants that randomly mix a little of each parent and a small amount of pure random mutation. After hundreds or thousands of generations, you display the most highly evolved candidate.

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Brainsonastick t1_ivcs3cn wrote

Replying to MrRumfoord (#459,707)

You can simulate it! There’s a class of algorithms called genetic algorithms. Basically, you write a code to convert from a string of characters to an object whose fitness you can test. In this case, a string of positions at which to fold the paper.

Then, you generate a bunch at random, test their fitness, and have the best ones interbreed. That means combining their strings (in a meaningful way) and adding random mutations.

That’s your new generation. Keep doing this over and over again and you’ll find the fitness of your planes, on average, increases each generation. After enough generations, you’ll get some pretty decent planes (assuming your code is good). Some might even be recognizable but a lot will super weird and surprising that they work at all.

There’s a simple video of a genetic algorithm evolving simple cars. It generates one capable of completing the track in only 37 generations. That sounds like a long time but on an evolutionary scale, it’s nothing. On a computer simulation time scale, it’s nothing.

And here is a more complex car evolution video that goes into some easily accessible explanation on how it works

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WeirdMemoryGuy t1_ivd03i9 wrote

Replying to jml5791 (#460,096)

The distinction between artificial and natural selection is itself artificial. We just kinda decided we didn't want to consider ourself part of nature. The selection process might be based on unique factors for us, but it isn't fundamentally different from natural selection.

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OneBeerDrunk t1_ivd18uq wrote

Replying to Jertob (#458,879)

Your comment is exactly the thoughts I have when learning anatomy and physiology. Sure some stuff isn’t perfect but like, for example, learning about intrinsic and extrinsic blood clotting factors, or really any homeostatic function of the human body, it really gets you thinking that some of the functions are just so complex and interactive that arising by chance is just so wild.

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Ksan_of_Tongass t1_ivd2cbm wrote

Replying to Jertob (#458,879)

Our little brains can determine where a moving object will be in time and space while performing actions to accurately put ourselves on an intercept course. This takes advanced math on paper but we do it instinctively.

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boltwinkle t1_ivd2euu wrote

Replying to Jertob (#458,879)

It's pretty incredible, right? The circumstances needed for life to arise were so specific, but it happened. We understand that organic compounds can come together to form structures that ultimately contain information, and these structures ultimately made the life we're surrounded by, including ourselves.

Never ceases to amaze me.

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eyesonthefries_eh t1_ivd4jeu wrote

Replying to strengr (#455,925)

Fun test: Usually the “support” webs going from the center out to branches or whatever are not sticky at all, and the webs circling the supports are the sticky ones. Touch them with your finger (gently), and it’s immediately clear which is which. Blew my minds the first time I heard this.

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tetrapod3d t1_ivdeasm wrote

Replying to Jertob (#458,879)

This is all easily explained by natural selection and evolution, immense complexity comes from simple beginnings, it just takes a long period of time and many generations to get there, our own brains are a great example of this.

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Stringy63 t1_ivdeclb wrote

Replying to guyonahorse (#459,034)

In your example, that is not random. A sentience is passing judgement on the suitability of the functionality of the paper creations. It seems so strange that the complexity of life could arise solely from disinterested randomness, a complexity that includes a consciousness that questions if it is randomness, or if there is sentience taking interest and making selection. It certainly could be random given the time scale. Seems at least possible there is a sentience involved. Okay, I'm going back to looking for good fart jokes now.

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zebrasmack t1_ivdffd9 wrote

Replying to Stringy63 (#461,316)

the "passing judgement" in real life is not dying before creating offspring. restrictions/parameters are the environment, with random changes and chaos within the environment. that's basically it.

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Tontonsb t1_ivdidsa wrote

Replying to Jertob (#458,879)

Imagine learning to walk on two feet? So many muscles have to intricately interact. So many things about shape, friction and solidness of the surface must be taken into account. You would think that needs a great understanding of physics. It's rather hard to program such behaviour, 10 years ago we hadn't managed to make a single robot that could normally walk on two feet.

However, babies can learn that in 1-2 years without having any idea of physics.

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Old_comfy_shoes t1_ivdj78i wrote

Replying to Jertob (#458,879)

I've seen spiders do things that makes me question their intelligence. There's a non-zero probability, in my mind, that they might be self aware. Or some species of spider might be.

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Al_Rascala t1_ivdjgaj wrote

Replying to WeirdMemoryGuy (#460,598)

Would the difference not be based on the mechanisms by which selection is carried out? Natural being the genome mixing via sexual reproduction that is common to most multicellular animals, artificial being direct manipulation of the genome via various tools?

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RandomFungi t1_ivdjuum wrote

Replying to tetrapod3d (#461,331)

Outside of truly exceptional events, there's not much that could actually extinguish human life on that time scale. You and I might not survive a nuclear war, but it wouldn't come close to killing every human, nor would global warming or a super volcano. Assuming we spread to orbital space and other solar objects almost nothing could kill all of us.

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tnoy23 t1_ivdk9zg wrote

Replying to Jertob (#458,879)

Spiders can be remarkably intelligent. The Portia Jumping Spider is a spider that preys specifically and solely on other spiders. It's smart enough to analyze the web of other spiders, know which strands to snip to make the spider it's hunting be less mobile and easy to catch, smart enough to know how slow to go to not alert the spider, it knows how many to cut and not cut, it knows the spider is essentially blind ((Jumping spiders are among a few spiders with good eyesight)) and it knows which strings of the web to pluck to emulate a bug trapped in the web.

https://www.youtube.com/watch?v=DEjYYY9KjnU - If you can handle the cheesy sound effects ((I can)) this is a documentary-esq video of the portia vs a long jawed orb weaver.

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Dumfing t1_ivdnc8l wrote

Replying to 0hip (#460,188)

Because evolution struggles to make large leaps with long term changes in mind (why are we still carbon based since the dawn of time?)

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Sable-Keech t1_ivdnjcb wrote

Replying to Peasant_hacking (#459,533)

Yes, the radiating lines are non-sticky while the circling lines are sticky.

Also when wrapping their prey they manipulate the sticky web with their claws which are coated with an anti-stick substance.

If you were to grab a spider and just slap it directly flat onto its own web it would probably get stuck.

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flintza t1_ivdp2gj wrote

Replying to Jertob (#458,879)

Others are giving some great answers around evolution, but I thought this might be interesting too. I’m reading it now, and among other things it goes into the structure of a bee’s brain, and how it achieves an incredible amount cognitively, with limited space for a brain. It’s a really fascinating read:

https://www.goodreads.com/book/show/59149209

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KilgoreTroutPfc t1_ivdu19d wrote

Replying to Jertob (#458,879)

It is a such a cool concept. But it’s really no different than how you know when it’s time to go to the bathroom. It’s all just feelings.

“Who could think of spinning silk number 5 at a time like this? Clearly this calls for a number 3.”

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Nyatwit t1_ivdu5oa wrote

Replying to MrRumfoord (#459,707)

Aka dragonflies.. They are not exactly on the top of the evolutionary chart but some of the most efficient fliers. The can fly forwards, backwards and hover.

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WinterPains t1_ive4isg wrote

Replying to Stringy63 (#461,316)

The sentience is acting as an artificial selection pressure.

Creatures change to fit their environment, due to selection pressures which affect what traits have the best survivability in that environment.

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Training_Ad_2086 t1_ive7p42 wrote

Replying to Al_Rascala (#461,543)

The human beings (us) that are doing genome manipulation are also created by evolution , hence this genome editing is something we evolved to do.

There are aquatic animals that can change their biological sex while alive, it's the evolution taking its course.

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