Respiratory organ in Pigeon

The flight activity requires a continuous and abundant supply of oxygen . Hence, the respiratory system of pigeon is highly developed and well differentiated. The respiratory system consists of external nostrils, glottis, larynx, trachea, bronchus and lungs.

The external nostrils are a pair of slit like apertures occurring at the base of upper beak. They communicate to the pharynx by internal nostrils. A glottis lies behind the tongue. It opens into the larynx. The larynx opens into a trachea. The trachea is a long, cylindrical and flexible tube running back- ward through the neck. On entering the thoracic cavity, the trachea expands into a syrinx or voice box. Later it divides into two bronchi, one for each lung. The walls of tracheal and bronchial tubes are supported by a series of closely set cartilaginous rings. Each bronchus enters a bright red lung. The bronchus divides and subdivides into smaller branches, ultimately ending in fine air capillaries. Lungs are solid spongy organs. They do not hang freely in the thoracic cavity but are lodged firmly in the ribs. Some of the branchial tubes pass through the lungs and communicate with the air cavities in the bone. There are nine air sacs. They are a median interclavicular, a pair of cervical, two pairs of thoracic and a pair of abdominal air sacs.