“Considering that spiders can already make really impressive geometric designs with their webs, it’s no surprise that they can take that leap to make an impressive design with debris and other things,”
Sure, but what is more interesting is how such a spider would know what itself looks like.
It doesn't have to know what it looks like; it only needs to "know" what its predator's food looks like, or rather, what its predators are more likely to hunt.
And that probably is "know", as in "built into its genes through evolutionary trial and error". It is not likely this is something mothers learn their children, or that they adapt the looks of their decoys within days if researchers let new predators loose (either might be true, but would truly be surprising)
There's no need for the spider to know what itself looks like. If it builds something that increases survival/reproduction, that trait will be selected for.
The spiders’ webs were crafted around face-height, near the trail
This makes me wonder if it was selected for stopping humans from wrecking their webs! It would explain why the decoys look like spiders, to humans.
Looking at the original article, it appears that the most spider like decoy photograph was chosen based on the appearance to humans - i.e. one with 8 legs which presumably you counted just as I did.
What appears spider-like to a fly, could be dramatically different - I'm imagining the process of trying to count appendages through a compound eye with a fly's brain and in the absence of the cultural system of symbols we use to represent numbers, etc.
It doesn't. It just likes to stick bits to its web in patterns. Feels good, (spider) man.
Something like this:
1. get bit of leaf.
2. go to center of web.
3. while standing on leaf bits, go down (with G).
4. drop bit of leaf, leaving gap to the left and right.
5. if more than 20 paces from the center. Forget it, relax.
6. goto 1.
With a bit of fiddling I have no doubt you can write a simple program to produce these shapes.
If you find this interesting, check YouTube for termite and wasp nest videos. Incredible!
The process of producing decoy shapes isn't really a problem. Why these spiders made the shapes is more interesting.
I think that the spiders that didn't create these decoy structures were selected against in the evolutionary process. The production of decoys could have been genetically engrained into their instinct (via mutation), or, this species really are actually able to recognize itself and create a decoy -- both of these cases would have led to less of them being eaten by predators, hence natural selection.
I can't wait to hear the results of the study after they research it more closely!
Which of these explanations seems more likely, in the context of a spider?
Spiders are very smart for their size (up to 80% of their body cavity is brain, and much larger than for insects), but giving them theory of mind is a stretch.
"That guy there wants to eat me. I look like this. If I make a thing that looks like me, he will think it's me and try to eat that, and I'll be safer."
vs. I just love to get bits of leaf and stick them just so!
Sure, it's a stretch, I don't dispute that at all. Maybe a spider witnessed another spider being eaten, and since it was spared, decided to make another spider-looking thing so it doesn't get eaten again. It's not really a matter of self-recognition or theory of mind, but more of a pattern recognition, something spiders (I assume) are good at. "My friend was eaten, and I wasn't. I should make something that looks like my friend so I don't get eaten." But, then again, Occam's Razor and all that. :)
The number of eyes isn't a particularly good guide. I'd guess most web-building spiders have quite poor detailed vision, as there's little need for it. Jumping spiders, which actively hunt prey, have good forward vision.
I think that implying the spider is actually able to recognize itself is a little too far. It would require a level of awareness comparable to that of apes and dolphins. Not even dogs are able to recognize themselves when put in front of a mirror.
While not a scientific article, here's an interesting read about corvids (crows, jays) presenting two sides of the argument that the birds possess theory of mind:
I would recommend reading "Sex on Six Legs: Lessons on Life, Love, and Language from the Insect World" by Marlene Zuk. It's a truly wonderful book about insects (and spiders too), about their evolution, and about how little brain power is required to display complex behavior.
Here are a few of my favorite, more on the philosophical side, quotes from the book:
Insects bring home the uneasy truth that you don't need a big brain to do big
things, and that in turn makes us question how the mind and, dare to say it,
the spirit, are related to the brain. It even makes us question what it means
to be human. What does it mean to have complex behavior? Does it mean you are
smart?
Natural selection can produce what looks uncannily like intelligent thought or
emotion but is no more than the relentless culling of minute variations in genetic
makeup, generation after generation, for millions of years. Not only that, but
insects too have small personalities, with some showing boldness in new situations
and some hanging back with what looks an awful lot like shyness. It's turning out
that we haven't cornered the market on individuality, either.
Insects are starting to answer the question of "What does it take?"—to have a
personality, to learn, to teach others, to change the world around them—with the
humbling and perplexing answer, "Not much." Humbling because they do these things
with brains the size of a pinhead, and perplexing because if that's all it takes,
what does that mean for us, with our gigantic forebrains and exhaustingly long
periods of childhood dependency?
Not that strong. For printer, the shape of a W is an external input. This spider outputs something resembling its own shape. So the question is here, why this and not something else (like randomly shaped clump), and how did it acquire this particular decoy blueprint.
Let me channel dawkins (and/or sagan) for a moment:
Imagine there's a cluster of spiders and a cluster of predators of those spiders. The predators can directly grab the spider, but if it fails and gets caught in the web, the spider wins. The predator is pattern matching on "what looks like a spider."
Maybe a few spider brains create reliable glitches in their webs. Maybe the glitches look enough like not-web where some predators get caught in the web when trying to catch the non-spider. The uneaten spiders-with-web-glitches reproduce and create further glitch making spiders. The predators not caught in the web (i.e. not fooled by the web glitch) also reproduce (n.b. the predators are reproducing glitch-avoiding pattern matching, so we have a glitch-vs-anti-glitch brain race), and some new spiders have more glitchy mutations making bigger anomalies. The anomalies looking more spider like will attract predators, and those spiders won't be eaten as easily. The uneaten spiders can reproduce more glitch-making spiders. The uneaten prey can reproduce more glitch-avoiding prey. The steady state of this model ends up with spiders reproducing themselves so the predator needs more and more advanced web glitch detection. Let this cycle go on for unbelievably long time scales (thousands? tens of thousands? hundreds of thousands? millions of years?), and you have a predator-prey derived "art."
The spider doesn't "know" it's intentionally making decoy spiders. It's just evaluating it's internal tiny spider brain state machine with evolutionarily derived glitches over the past ginormous number of years.
Yes, Exactly! Another similar example would be the process that produced the heikegani crab.
TL;DR - Over years fishermen threw crabs with face-like patterns on their carapaces back into the ocean. Over time this produced crabs with extremely detailed faces, increasing the chances they wouldn't be eaten and could reproduce.
We often hear about how long mammals' or birds' characteristics took to evolve, I'd like to have a grasp of the scale of time we're dealing with when talking about tiny creatures like these.
I have absolutely no idea of the time that is necessary for such characteristic to evolve, but I think it's not that much time when talking about insects or arachnids. Evolution is not iterated over time, it happens over generations. And when talking about insects or arachnids, we have a lot of them in a short span of time.
You raise an interesting topic I've never really given much thought to (time vs generations). Makes me think of other questions about genetics that I just don't know the answers to but that someone must have thought of.
Things like:
How do they account for recessive traits?
Can something that is recessive become dominant?
Can something dominant just disappear (I imagine that it could with mutations happening so much)?
Is there a specific animal they use to test these things?
Do different traits take longer to evolve towards?
I imagine they use something that reproduces rapidly (fruit flies? fleas?).
On the topic of this spider and how does it know what it looks like...I don't know how much brainpower the spiders have but I know that we have a part of the brain that tracks where our body is (at least in relation to other body parts). Is it possible the spiders have something similar?
Can this even be used to make a rough representation of oneself?
I am going to have to google some of these later as I'm now curious.
How about a printer with a picture of itself built-in as a test page pattern? :)
I'd guess that its sculptures started as fairly undefined clumps that served the purpose somewhat well (presumably that's what's built by other "sculpting spiders" that the article mentions?). And then evolution has refined that clump, like it does so well.
Having trouble viewing the video but what's blowing my mind right now is that in the picture I see, it has created a decoy with 8 legs. How does it know??
The writer/editor chose that picture. Scroll down and there's a 5-legged decoy. It's still cool, but they chose the most impressive picture to lead with.
Looks like it. If one clicks through to the blog post, there are photos of two more decoys, both with <8 legs. But I guess most predators don't stop to count legs, so the evolutionary pressure for better decoys isn't that high.
Apparently spiders aren't the only ones with a long history of evolved behavior; before I even recognized what I was looking at, I had an immediate "WTF?!?!?!?!" fight or flight response to that fascinating image of a mother spider with many tiny spiders on its back.
Could this decoy be used in the mating ritual to attract females rather than something to do with predators? From my limited reading, many spiders have rather elaborate mating rituals. Also with females being larger and usually killing the smaller male spiders, having a decoy to distract the female might allow the spider to stay alive longer and mate with more female spiders.
I think it's the male that goes to the female in such cases. The decoy could perhaps be used to attract males. But I'm not an arachnologist, so there may be some obvious reason why that's not the case.
Wow, just wow. Not that I'm a big fan of spiders mind you but a spider that creates 'fake' spiders as decoys? That is pretty amazing. Thanks for sharing it.
my question with this hypothesis is, why does the clump-building behavior end up with something that looks like a spider and not something that would give the spider an even greater evolutionary edge, like say, a tiger's face?
I think the benefit might be less of scaring away predators, but just acting as an alternative, bigger target for them. Anyone looking at spider webs for a meal will immediately go for the large obvious spider-looking thing in the web, and while that predator is dealing with the confusion of getting a mouthful of debris and gunk the real spider can make a get-away.
Right. The big spider shape is a hack that exploits the spider-detecting system of the predator. The predator has a very powerful response to spidery things. It's like a flare to an older/cheaper heat seeking missile.
If the decoy becomes too successful, the predator will evolve to have more sophisticated detector, find something else to eat, or become extinct.
Modern heat seeking missiles have fancy multi-frequency heat detectors or even IR CCD cameras with image processing to ignore the flares.
good point. but this means that step 1 has to immediately be appetizing to be of evolutionary benefit. (arguably it could be). It also conflicts a little bit with the observed behavior that the spider is shaking the web, trying to get attention to the bigger spider. If the true benefit was escape, I would think not-attracting attention would be the resultant behavior.
Just my opinion. I guess we don't know for sure. There's probably a way for some biologist to figure that out for certain - would make an interesting postdoc.
Step 1 doesn't need to be that appetizing if the cost of building the decoy is low. Any benefit, as little as it may be, is already an advantage if it covers that cost.
About the attention-seeking behavior, we can compare it to the same behavior geckos adopt when they find themselves in danger: they start shaking their tails vigorously to attract the attention of the predator to the tail (geckos are known for being able to detach their tails in these cases, and once detached the tail keep shaking vigorously, potentially attracting the predator giving the gecko a chance to escape). In both cases, the spider and the gecko seem to only engage in this behavior once they already have the predator's attention, so trying to escape without shifting the predator's attention to the decoy could actually put the attention on them.
> but this means that step 1 has to immediately be appetizing to be of evolutionary benefit.
It doesn't necessarily have to be appetizing. Any amount of confusion, hesitation, etc. it can cause is potentially beneficial. Even if only one in a thousand predators hesitates or attacks the wrong spot one in a thousand times when it sees a decoy, that's going to have an effect over millions of years.
The first half was great but the narration was not very good towards the end.
I finished it though because it was fascinating. Reminds me of the birds that have elaborate rituals and when I think of the bug versions they are much less exciting.
The spider was 'almost' cute but then I saw some of the other suggested videos and remembered why I don't like them.
What's amazing is there are probably many species of bugs just waiting to be found.
It seems like spider weaving is such a natural and central ability to spiders. What's more it's hackable. Some wasps inject chemicals that manipulate them to create a habitat for their eggs and be even eaten alive.
the questions is how does he know how he looks like?
is he looking at other spiders? maybe he looked into a reflection on the water? or does he simply just know?
Don't all animals "know" to some degree? After all, they "know" they're attracted to mates of the same type. Though I guess sometimes a dog humps a leg.
Sure, but what is more interesting is how such a spider would know what itself looks like.