Is giant "bugs" possible??

Keith keith at pop.onwe.co.zanzibar
Sat Sep 13 06:07:58 EST 1997


Zac Forsman <zforsman at Bayou.UH.EDU> wrote:




>Hello, I'm a Graduate Student at the University of Houston, and I think I
>can clarify your quandry.  The limiting factor to insect size has more to
>do with constraints of an external skeleton then environmental condidions
>like Oxegen. Have you ever noticed that very large insects break easily?
>It's difficult to repair an exoskeleton, it's not living tissue (like your
>hair or fingernails).  -The larger the egg, the easyer it breaks, because
>the building materials work well at a small scale, but not at a large one.
>The largest insects in the carboniferous period were never any larger then
>the largest insects today.  The giant dragon flies had a wing span of up
>to a foot, aproaching the upper limit of what is possible for insects, but
>if you take volume into account, there are beetles that are just as large
>today.  
> Oxegen does have an important role in the size of
>insects.  Most insects resperate (breath) through small holes called
>sphericals in thier abdomens.  There is a direct correlation between
>organism volume, and complexity of breathing aperatus -because small
>things diffuse oxigen easily (you need complicated mechanisms to get air
>to a-lot of volume).  That's why there are not giant ameboas, no giant
>single celled bacteria, etc. . .  Make sense?

>Zac,
>   Department of Biology
>   University of Houston

Something you left out is the fact that the exoskeleton is also
unbelievably heavy, and over a certain size limit no insect could
lifet it.


Keith Norris
University of the Witwatersrand
South Africa
keith at gecko.biol.wits.ac.za
keith at pop.onwe.co.za

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