A weird question inspired by giant bug movies.

Discussion in 'Archived Threads 2001-2004' started by DerrickRemmert, Jun 19, 2002.

  1. DerrickRemmert

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    Eight Legged Freaks and Starship Troopers made me start wondering about a stupid question. If insects and spiders were gigantic, would they still be able to run and jump with lightening speed? Or would they be squashed by their own weight or just creep around slowly because they'd weigh so much?
    Why doesn't Jeopardy ever ask these kind of questions?! [​IMG]
     
  2. Paul_Fisher

    Paul_Fisher Screenwriter

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    Insects could never ever be that big. They are limited by their exoskeleton.
     
  3. Jay H

    Jay H Producer

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    Well, spiders are not insects, they're arachnids, but if say you had a 50ft tall spider, I would imagine they would have to really evolve into having better hydraulics, because spiders kind of move by "hydraulics" controlled via a very primative nerve system. They basically have to hold their breaths as they move which is why you see spiders sprint and stop and sprint and stop. It is because they have to breathe and they can't move and breathe at the same time. If they were say 50ft tall, the hydraulics and motors would have to be stronger accordingly to push all those fluids around. Sort of like the hydraulics on a forklift, the bigger the forklift, the stronger the pump and more hydraulics.
    And arachnids aren't limited by their exoskeleton, that is why they molt or shed their exoskeleton when they grow. They basically grow the second exoskelton inside the old one (there is a layer of fluid between the inner and outer skelton so when the spider grows, that fluid is reduced such that the inner skelton will eventually replace the outer skelton and the spider "grows"). When the spider molts, the exuvium is expelled and the new skeleton is soft and mushy for a couple days and then it hardens.
    I think if we happen to discover a huge 50ft tall spider, I don't think it would be as speedy as a smaller spider, relative to it's size just because the hydraulics is simply not that advanced.. They would really need to evolve something better like an inner skelton and muscles, much like the way humans and other animals are. Face it, an exoskeleton isn't the best way to design a fast and mobile animal, it's bulky and inflexible. However, it is effective as a defensive mechanism. So to answer your question to the best of my knowledge, I think a 50ft spider would be cumbersome and lanky. At least until they evolve into a better arachnid, at which case, watch out cause us humans must be pretty tasty to them, at least when they get bored of crickets... [​IMG]
    Jay
     
  4. Kevin M

    Kevin M Producer

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    On a planet with less gravity it might be possible. But I would think avians would rule the chain on such a world.
     
  5. Darren Davis

    Darren Davis Stunt Coordinator

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    no, they wouldn't retain all of their previous abilities. It has to do with their new size. Say the insect is made three times as tall, then this (according to size change property of geometry) would make the weight of the insect 3^3. As it gets bigger and bigger it becomes harder and harder to support the weight.
     
  6. JohnAD

    JohnAD Cinematographer

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    Darren:

    Actually mass increases by volume, so it would be 3x3x3, or 27 times.

    Jay:

    All arthropods, which include insects and spiders, have an exoskeleton, and so spiders would be limited in a terrestrial environment. The reason why we only see large arthropods in the ocean is that water is much more dense than air, and can support the added weight of the larger exoskeleton. Basically, we probably won't *ever* encounter really large (i.e. man-sized or larger) spiders.

    John.
     
  7. BrianW

    BrianW Cinematographer

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    Darren & John got it right in that an object’s volume, and therefore its mass, increases exponentially in relation to its length. So giant bugs would not retain their abilities to carry several times their own body weight or jump many times their own body length. Similarly, if you were to shrink a person down to the size of a flea, our proportional strength would be astounding. Although we still wouldn’t be able to out jump a flea, we’d be able to jump several times our own body length.

    Another reason bugs are so small is because they don’t have lungs. Most of them gain oxygen through their skin with tiny holes acting as bronchial exchange mechanisms. This would be like obtaining oxygen through your hair follicles rather than through your lungs. The volume of all your hair follicles put together wouldn’t amount to enough bronchial structure for you to live on. And as bugs grow (maintaining proper aspect ratio, of course), their surface area to volume ratio decreases, which means that their bronchial mechanisms don’t grow as fast and must support an increasingly larger organism. Beyond a certain size, the organism becomes unviable.

    As far as exoskeletons go, it is certainly true that bugs are adapted to their present size, and the exoskeleton designs they now employ would not work well if they were drive-in monster size. But that doesn’t make exoskeletons an inherently bad design for large organisms. With a little redesign, I’m sure very large exoskeletal creatures could be quite viable.
     
  8. Jay H

    Jay H Producer

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  9. Neil Joseph

    Neil Joseph Lead Actor

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    I think size plays an important factor and indeed it would slow down the insect. Could you imagine a human sized ant crawling around at 100kph?
     
  10. andrew markworthy

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    In the case of Starship Troopers, I think a more pertinent question is - will humans really be that stupid within a couple of generations?

    Returning to the question - neat answers already given, and nothing to add re: the physiology. Re: the psychology. Insects and spiders have v. primitive cognitive skills - the feats of social insects such as hives, complex social orders within nests, etc, are all down to a few simple hard-wired genetic instructions rather than learning or a shared intellectual culture as we would understand it. Therefore, the idea of cunning attacks and lightning-fast reactions as seen in numerous movies are extraordinarily unlikely.
     
  11. JohnAD

    JohnAD Cinematographer

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    Well, yes, but you also have to remember that the bugs in Starship Troopers aren't merely insects. The 'brain bugs' communicate telepathically (IIRC) to the other castes, so they can, in fact do what they did (within the scope of the book/movie).

    But you are essentially correct. Even with pheromone messaging, such real examples as wasps and army ants wouldn't be capable of such an attack.

    John.
     
  12. Bill Catherall

    Bill Catherall Screenwriter

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    Andrew - That's still not the most pertinent question.
    The most pertinent question is - when do we get the co-ed showers? [​IMG]
     
  13. Garrett Lundy

    Garrett Lundy Producer

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    Assuming "giant" bugs use the same chitinous exoskeleton as regular bugs. No, after an insect became several feet long, (assuming all porportions were the same) the weight of the chitin would become too heavy to move. about the size of a large car the exoskeleton would collapse on itself.

    Carpenter ants, scorpions, and spiders the size of large dogs could technically be possible, but I'm sure they don't exist for a reason (Probably too slow).

    Alternate theory to why bugs are small: Circulation. Most bugs do not have a complex series of arteries, veins, or even complex lungs & hearts that "higher" animals do. Oxygen is delivered to the individual cells in a "blood shower" type of delivery, where the cells are bathed in oxygen rich blood, before returning through a singal chambered heart to start again.
    After a certain size is reached, the simple heart would no longer be able to support the many billions of more cells needed to make up the giant insect. an entire circulartory system would need to evolved to keep the things alive. Not to mention the sugar-water food that most insects use would no longer be able to be had in large enough quantities. As small bugs, very tiny bodies let food and oxygen enrichened goo pass through their bodies in moments. allowing more energy to be burned and work to be accomplished. a school-bus sized ant would have to eat tons of raw foodstuffs a month just to keep-up with their own 24/hr workdays, and would quickly destroy the ecology of the planet.

    Blah
     
  14. JohnAD

    JohnAD Cinematographer

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  15. Denward

    Denward Supporting Actor

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    I have nothing to add but to say this is a cool thread. It could be heading toward archive quality! [​IMG]
     
  16. Yoshi Sugawara

    Yoshi Sugawara Stunt Coordinator

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    Most of the explanations above are correct, and just to expand on one point:

    Insects obtain oxygen by diffusion, where oxygen "seeps" through to the circulatory system. Diffusion is slow and is only effective across small distances. So an overly large insect wouldn't be viable.
     
  17. JohnAD

    JohnAD Cinematographer

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    Yup, although having a large surface area to volume ratio helps.
    BTW, Derrick, thanks for starting such a fun thread [​IMG]
    John.
     

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