are the tiny holes for?
biologist Dr. Karen Oberhauser explains: "Monarchs
'breathe' through tiny openings on the sides of the abdomen and
thorax called spiracles. The spiracles
are in their cuticle, like our skin. The reason that I put quotes
around the word 'breathe' is because this is very different than
the kind of breathing you do. Monarchs don't have lungs. The air
goes into their spiracles and through a whole series of tubes
in the body called trachea. The trachea carry oxygen throughout
the monarch's body."
are limited in size because of this inefficient system of air
exchange," says Dr. Lincoln Brower. Insects
cannot be more than about 1 inch thick. "Insects could be the
size of Sherman tanks and dominate the world if they had our mode
of respiratory system!" he exclaimed.
Image © Journey North