* Astronomy

Blobrana · L

RE: Insects

Blobrana · L

For the giant insects that roamed Earth 300 million years ago, there was something special in the air.
A higher concentration of oxygen in the atmosphere let dragonflies sometimes grow to the size of hawks, and some millipede-like bugs reached some two meters in length, a new study suggests.
Now that the proportion of oxygen has decreased, however, bugs can't grow much larger than they do now, the authors write.
The reason: The bigger an insect, the bigger the proportion of its body devoted to its tracheal system, which functions like a lung but is far less efficient at large sizes.

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Blobrana · L

Higher concentrations of oxygen could produce giant insects according to a paper presented at the Comparative Physiology conference currently meeting in Virginia Beach, Virginia.
The paper, "No giants today: tracheal oxygen supply to the legs limits beetle size," based on research by a team of American researchers, offers evidence that Palaeozoic insects were substantially larger because they had a richer oxygen supply. During the late Palaeozoic period, about 300 million years ago, the air's oxygen content was around 35 percent, compared to 21 percent today. As a result some dragonflies had two-and-a-half-foot wing spans, while giant spiders roamed the ancient forests.

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