- A respiratory opening connected to the tracheae.
- A lateral articulated plate of a segment.
- An internal sac comparable to a lung.
Show answer
Correct answer: 1.
A respiratory opening connected to the tracheae.
Why?
In insects, a spiracle is a small opening located laterally on the thorax or the abdomen. It allows air to enter the tracheal system.
In the adult bee, one usually counts 10 pairs of spiracles: 3 pairs at the level of the thorax and 7 pairs at the level of the abdomen. These openings are therefore not lungs, but entry points to a network of tracheae and tracheoles.
What to understand
The bee does not breathe like a mammal. Oxygen does not pass through lungs or through red blood cells: it circulates in a network of tubes that brings air as close as possible to the tissues.
The movements of the abdomen observed in a motionless bee may take part in the ventilation of the tracheal system. They must not, however, be interpreted as a pulmonary respiration comparable to that of a human being.
The term "pleurite" refers to a lateral plate of the insect's body. It must not be confused with the spiracle, which is the respiratory opening itself.
Key takeaway
A spiracle is an external respiratory opening. It is connected to the tracheae, which ensure gas exchange directly at the level of the tissues.
In the bee, the spiracles are located on the sides of the thorax and the abdomen. The bee has no lungs.
Further reading
► Internal anatomy: General points