Today’s interesting fact has to do with Birds and how they breathe.

Birds have a more efficient breathing system than mammals do.

Birds have up to nine air sacs in their bodies, which help reduce their overall weight but also both store air and act like bellows allowing fresh air to constantly flow through the lungs during each cycle of inhale and exhale.

Mammals use a bidirectional airflow in their lungs which moves the air in and out. This means that air that has been depleted with oxygen is mixed with fresh air with every breath.

Birds because of the way their lungs and air sacs are designed breathe with a unidirectional airflow, so that the air makes a circuit in the lungs. This means that air is never mixed, and is always fresh.