Question

What helps them to breathe?

Answer 1

Hint:-Cranes are birds and they belong to Class Aves, Order Gruiformes. They are long-legged and long-necked migratory birds. At present only 15 species are found which are further classified into 3 genera viz., Antigone, Balearica, and Grus.

Complete Answer:-
Birds are adapted to an aerial mode of living. They have a highly efficient respiratory system which helps them to breathe efficiently even during flight. The main respiratory organ in birds includes a pair of lungs. However, due to its small size and inelasticity, they do not inflate or deflate during breathing. Cranes inhale fresh air through their nostrils which is then carried to the lungs. The flow of air is continuous and unidirectional in lungs which means the air moves in one direction and does not get mixed with stale or residual air. This is a unique characteristic of birds as each breath brings along a maximum amount of oxygen (nearly 21% present in atmospheric air) to the capillaries in lungs.
Additionally, to compensate for the steady flow of air for breathing and energy required during the flight, birds have accessory respiratory devices called air sacs. These are thin walled tubular structures which protrude out from the outer margins of the lung and occupy the body cavity. These help the bird to store and supply air even during flight. These also maintain buoyancy during flight.

Note:- Birds do not have a diaphragm. The respiratory system plays an important role in thermoregulation i.e., maintaining normal body temperature. Birds produce huge amounts of heat when they are in flight. This heat needs to be dissipated. Air sacs act as coolants.