I made it easier to save:Some cool things about chickens.....
The chicken has pneumatic bones, making its body lighter for flying, if it had not lost the ability to do so.
There are 13 air sacs in the chicken's body, again to make the body lighter, and they are a functioning part of the respiratory system.
Chickens have comparatively short life spans. Some live to be 10 to 15 years old, but they are the exception, not the rule. In commercial egg production, birds are about 18 months old when they are replaced by new, young stock.
From Rons link I am nosein at.... http://urbanext.illinois.edu/eggs/res08-whatis.html