Theory 49/Biology & physiology/Insect water balance
Spiracle Control Is Demand Against Loss
The claim
Insects open spiracles only when the ratio of respiratory demand to water loss cost exceeds one, which is why they breathe in bursts in dry air.
01Mechanism
Gas exchange requires opening the barrier; the ratio determines the duty cycle.
02Prediction
Opening should track the ratio.
03Refutation
Opening tracking oxygen need alone would remove water cost.