Which Vertebrates Exhibit a "Flow Through" Respiratory System

Question

Which vertebrates exhibit a "flow through" respiratory system?
A)mammals
B)birds
C)amphibians
D)fishes
E)birds and fishes

Accepted Answer

Birds and fishes exhibit a "flow through" respiratory system. In birds, air flows through their lungs in one direction, which is more efficient for gas exchange. Fishes have gills that water flows through, also in one direction, allowing for efficient oxygen extraction from water.