gas exchange in insects

hi, insects are small so have a large sa to volume ratio, so why can't gases can just diffuse through the spiracles without needing the tracheal system?

(edited 2 months ago)

Reply 1

goldencanary

Original post by goldencanary

hi, insects are small so have a large sa to volume ratio, so is that why gases can just diffuse through the spiracles?

and why can't oxygen pass easily through the exoskeleton?

(edited 2 months ago)

Reply 2

Nitrotoluene

Original post by goldencanary

hi, insects are small so have a large sa to volume ratio, so why can't gases can just diffuse through the spiracles without needing the tracheal system?

In general, despite insects having a high surface-to-volume ratio, which would appear to facilitate the diffusion of gases inward through their spiracles, several factors are actually at work. The speed with which gases can move and how well they diffuse along with the amount of pressure, airflow, oxygen they need, and the adaptations they transitioned through appear to necessitate a special tracheal system.
Krgds,
Sandro

Reply 3

Kallisto

Entertainment Forum Helper, Life & Style Forum Helper

@DerDracologe
As someone who has taken biology at A levels and specialized to zoology this question is tsilor-made for you, if you can add some facts which were not mentioned so far.

Reply 4

DerDracologe

Study Forum Helper

Original post by goldencanary

hi, insects are small so have a large sa to volume ratio, so why can't gases can just diffuse through the spiracles without needing the tracheal system?

Insects have a hard exoskeleton which prevents direct gas exchange between cells and the surrounding air which means gas exchange needs to take place internally. It is most effective for insects to have many spiracles and tracheae because this means a greater volume of air can be conducted into the airways at one time. This is especially important given that insects have high metabolic requirements, particularly when they are active. The gas exchange system in insects also allows for them to increase the supply of oxygen during periods of intense activity, for example via mechanical ventilation.