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smtf | 13 years ago

“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.

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pron|13 years ago

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?

pagliara|13 years ago

Thank you for the recommendation. You've inspired me to go read this right now.

Someone|13 years ago

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)

6ren|13 years ago

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.

VMG|13 years ago

way too little time to evolve that behavior

brudgers|13 years ago

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.

http://blog.perunature.com/2012/12/new-species-of-decoy-spid...

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.

See Thomas Nagel's What is it Like to Be a Bat? http://books.google.com/books?id=fBGPBRX3JsQC&pg=PA165#v...

return0|13 years ago

Flies are not predators for spiders.

CamperBob2|13 years ago

It would be interesting to amputate a leg from the spider in infancy and see if it creates a seven-legged simulacrum as an adult.

jayflux|13 years ago

Spiders legs grow back when you remove a leg from them.

robotresearcher|13 years ago

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!

mirkules|13 years ago

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!

ry0ohki|13 years ago

A spider has to instinctively know what a spider looks like, otherwise how would it know what to mate with?

VMG|13 years ago

Knowing what it looks like doesn't mean knowing how to build it.

Fargren|13 years ago

Do the mate with each other or do they lay and impregnate eggs?

seiji|13 years ago

"know" is a bit of a strong word here. Does a printer "know" what a W is or does it just know where to put the dots?

TeMPOraL|13 years ago

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.

skc|13 years ago

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??

robotresearcher|13 years ago

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.

solox3|13 years ago

More likely the case is it knows what its mother looks like.