Similarity between Spiracle of Cockroach and Nostril of Man

Introduction:
Cockroach is an arthropod and Man is a mammal. Though both belong to different phyla, both have a respiratory system. The respiratory system of cockroach and man have similarities and differences. One such similarity is the presence of spiracles in cockroach and nostrils in man.

Spiracle of Cockroach:
Spiracles are the openings present on the lateral side of the body of cockroach. They are used for respiration. Air enters through the spiracles and diffuses into the tracheal tubes. The tracheal tubes are then further branched into smaller tracheoles which end in tracheal cells. The exchange of gases takes place at the tracheal cells.

Nostril of Man:
Nostrils are the openings present on the front side of the face of man. They are used for respiration. Air enters through the nostrils and passes through the nasal cavity. The nasal cavity is lined with mucous membrane which filters, warms and moistens the air. The air then passes through the pharynx, larynx, trachea, bronchi, bronchioles and finally reaches the alveoli. The exchange of gases takes place at the alveoli.

Similarity:
The similarity between spiracle of cockroach and nostril of man is that they both are openings used for respiration. They are the entry points for air to enter the respiratory system.

Difference:
The difference between spiracle of cockroach and nostril of man is that spiracles are present on the lateral side of the body while nostrils are present on the front side of the face. Also, spiracles lead to tracheal tubes while nostrils lead to nasal cavity which further leads to different respiratory organs like pharynx, larynx, trachea, bronchi, bronchioles and alveoli.