(Image pilfered from Vikusik on Flickr.)

Imagine what it would be like if this cute little dragonfly, cruising around your backyard, had a two-foot wingspan. It’s not sci-fi — it’s ancient history. Such giant dragonflies were a common sight in the swamps and coal forests of the Paleozoic era. Five-foot long millipedes, too.

Recent research gives clues as to why, and the answer may surprise you:

It’s a series of tubes.

Beetle air tubes

(A series of beetle tubes. Called tracheal tubes, these are the insect’s way of breathing. Bugs don’t bother with lungs. They just absorb air directly through their tracheal tubes, which penetrate throughout their bodies. Image stolen from an Argonne press release.)

To find out what the series of tubes has to do with the size of an insect, <shameless plug> check out my article about it in Discover </shameless plug>. Hint: it has to do with atmospheric oxygen concentration.

And if this makes you wish with all your heart that you could time travel back to the Paleozoic to see those 2-foot-wingspan dragonflies, you might try to get your hands on the WowWee DragonFly. It has a paltry 1-foot wingspan — but you get to control its flight.