If the atmosphere in the past held more oxygen, tracheae could be narrower and still deliver enough oxygen for a much larger insect. This would lead to a much larger size limit, Kaiser concluded.

Known as tracheae in insects, the tubes split into ever smaller branches, ending in ultra-fine end sections that deliver the respiratory gas into the tissue.

Eventually tracheae cannot develop beyond a certain size. Based on their calculations, the researchers figure modern beetles cannot grow larger than about six inches.

These tracheae can grow up to 2 micrometers across in dragonflies, roughly 38 times smaller than the width of a human hair. Technique. These images were created using confocal microscopy. Tags.

Contraction of the tracheae, the x-ray movies revealed, expelled as much as 50 percent of the air volume at a time, depending on the species of insect.

IN NATURE (vol. xvii. p. 284) is a notice of a work by Dr. Palmen, of Helsingfors, on the morphology of the tracheal system. From the wording of the notice it appears as if the views of Dr. Palmen ...

These tracheae start at openings in the exoskeleton called spiracles, which allow oxygen into the insect’s body. The network of tracheae also allows carbon dioxide produced by the insect’s metabolism ...

The additional oxygen meant that an insect's tracheae could be relatively small compared to the rest of its body, and still channel lots of oxygen. All of that oxygen resulted in super-sized insects.

I think we can safely infer that extinct birds with long, looping tracheae - like those moa - made loud, striking calls too. After all, these pipes closely resemble the loops in tubas, french ...

What's the Context: Earlier windpipe transplants have also used tissues derived from the patients' stem cells---but the tissues were grown on donor tracheae, not artificial scaffolds, meaning that a ...