Big Bugs Need To Breathe

After my bike buddy and I noted the striking similarity between our praying bike rack supervisor and the big bug from Men in Black, I was happy to find this post from Science Blog. It has long been theorized that the age of the giant bugs in our fossil record correlated quite nicely with the sediment record for oxygen concentration in our atmosphere. The more oxygen there is, the bigger the bug can get. After an ecological upheaval, the oxygen levels went down, and now we have regular sized land based arthropods. So can we really test that oxygen levels were the basis for big bugs? Using x-ray techniques to examine the tracheal passages of several species, we see pretty good evidence that oxygen is the key. Huge beetles have more airways in their bodies than smaller insects, especially in their legs. Using calculations to see how big a predicted beetle could get, testing whether airways were more important if they were connected to the head, or if the limbs were better, the team at Argonne National Laboratory found their predictions for maximum beetle size matched fairly well with the largest known species. So, now we know, the big bug wearing the Edgar suit has a lot of tracheal tubes in his legs, and probably evolved on a high oxygen atmosphere planet. I'd still say my prayers if I ran into it though.