Although most humans probably do not lament the disappearance of dog-sized insects, a handful of scientists do. These scientists obviously don't watch the same movies we do. Recently, a group of researchers from Argonne National Laboratory's Advanced Photon Source along with some other researchers from less badass sounding institutions used advanced x-ray equipment to try to determine why giant insects don't roam the earth devouring amorous teenage couples today.
X-ray imaging of beetles helps confirm that tracheal system design may limit size in insects.
The answer lies in their primitive respiratory systems. Unlike vertebrates in which oxygen is transported via the lungs to the blood and then throughout the body, insects transport oxygen via a network of blind-ending tracheal tubes. Pathetic! By examining different sized beetles, the scientists discovered that as the size of a beetle increases, the size of the tracheal tubes required to keep the bug going with a good O2 buzz increases disproportionately. This means that the larger the insect, the less room there is for other organs as tracheal tubes crowd everything else out.
In the late Paleozoic Era, when monster bugs were all the rage, oxygen levels were at record highs. As oxygen levels decreased, however, the cuddly teddy bear-sized insects disappeared as well. Perhaps not coincidentally, this subsequent period also gave rise to the picnic.
Comments
At schoool I was told that insects can't get much bigger for two reasons - this one, and their legs. As bodies get bigger, of course, their weight increases cubically, whereas the cross-sectional strength of a leg only increases by the square, which is why flies have really thin legs, humans have thick ones and elephants have really thick ones. How did meganeuropsis deal with this?
Posted by: Jon Eccles | August 22, 2007 12:41 PM
I soooooooo want a dog-sized beetle for a pet! I could tether him outside and let him mow my lawn, like a goat. I would take him for walks around the neighborhood, and all the pit bull owners would cower... waitaminute...
Would there be bug fights instead of dog fights??? We would have to set up a rescue foundation for abused fighting bugs!
And there would be bug shows!!! Every breed of dog-sized insect would have different standards of bug-perfection to be judged. And there would be agility training! And Stupid Bug Tricks!!!
:::SIGH:::
I would name him Fido.
Posted by: Melissa G | August 22, 2007 2:29 PM
There are still giant arthropods around. Consider, for example, the bat-eating centipede...
http://youtube.com/watch?v=PgLmUb5P_Ws
It would be interesting to find out how it works around the tracheal tube problem.
Posted by: Owlmirror | August 22, 2007 6:29 PM
Very nice writing style boys. This is the kind of thing that can make science interesting and approachable to the average lotto addict.
Posted by: Ted | August 22, 2007 8:27 PM
Thanks for this blog guys! Very entertaining :) Makes me feel all warm and fuzzy inside ;)
Cheers!
Posted by: Beluga | August 23, 2007 5:39 AM
Not have that tracheae internal pumps?, and many active insects have many systems of ventilation what solves that problem.....
Or the problem is rather to moult an exoskeleton on land, while is teneral, an insect is soft and a very big one would collapse.....
Posted by: Edgar | September 11, 2007 6:16 PM