Among aquatic, water-breathing animals, gills and other continuous-flow breathing methods dominate over lungs and other storage-based breathing methods as in land animals. Notably, axolotls have gill-like structures around their heads which use a high surface-area structure heavily vascularized with capillaries to breathe water.

However, it seems all air-breathing organisms use storage-based breathing, air-breathing fish included, as lungfish use their swim bladders as lungs, a clear example of storage-based breathing.

Are there any land organisms that use continuous-flow breathing methods over lungs?

  • $\begingroup$ That emphasizes that fish with only gills would have had much difficulty in adapting to land for the same reason that electric tyre pumps and manual tyre pumps are different. $\endgroup$ Apr 15, 2020 at 2:48

3 Answers 3


Terrestrial crustaceans are land animals that use gills (or gill-like structures) for gas exchange, though these gills must be kept moist for efficient respiration.

Specifically, animals like hermit crabs have a branchiostegal lung that looks like gill tissue but is better adapted for absorption of oxygen from air instead of water.


Modern reptiles (including birds, but possibly excluding turtles) have a continuous flow system of lungs. In birds, the lungs have air pushed over their lungs by larg air-sacs, similarly to how water is pumped over gills by the mouth in fish


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