“Bugs don’t breathe like we do,” he began finally. “Air comes in through holes in their abdomens and shuttles along tubes.” “You mean they don’t breathe in and out, right?” “Right. It’s passive. The air just kind of travels through them. Which isn’t as efficient as our system. So the bigger the bug, the harder it is for it to get the oxygen it needs. In prehistoric times, the oxygen content of the atmosphere was fifty percent higher than it is now, so the bugs back then could grow a lot bigger. Hundreds of millions of years ago, there were dragonflies with two-foot wingspans.”
