How Do Animals Breathe? explains the four breathing methods of animals of animals.

  • Lung breathing: Mammals, birds, reptiles and some amphibians
  • Gill breathing: Fish and crabs
  • Tracheal breathing: nsects, centipedes and spiders
  • Skin respiration: Amphibians, z. B. frogs
Why Do Animals Have To Breathe?

Breathing supplies organs and muscles with oxygen, which every animal needs to survive.

How Does Breathing Work?

Breathing in and out is controlled by muscles (except skin respiration). During pulmonary breathing they widen the rib cage for instance. When breathing out, the muscles relax and contract the rib cage again.

What Happens When Animals Breathe?

When breathing in, the air is pumped into the organs of the respiratory system (e.g. lungs). Delicate blood vessels extract the oxygen from the air. The blood helps to transport the oxygen to the cells and tissue (exception: tracheal breathing) to be “processed” there. All there is left then is some carbon dioxide, which is transported out of the tissue and cells when breathing out.

How Do Animals Breathe? How Do Animals Breathe? - Illustration: Silke/

Are There Similarities Between the Different Breathing Methods?

All breathing methods help to transport oxygen INTO the cells and the remaining carbon dioxide OUT of the cells.

What Are the Differences?

The respiratory systems and the airways through the body differ:

OrganOxygen Transport
Lung via the blood
Gills via the blood
Trachea via the trachea
Skin via the blood
Gills Today, Lungs Tomorrow – Example: The Tadpole

Some animals undergo a bodily transformation (metamorphosis) when growing up. Even their respiratory systems might change completely. For instance, the tadpole has gills to be able to breathe under water. The gills regress during the metamorphosis, and the adult frog uses its skin and lungs to breath. Learn more about the metamorphosis of the tadpole into a frog under: frogs and toads.

How Respiratory Systems Developed in the Course of Time

Skin respiration is the most primitive method and can only supply small animals with oxygen. The next steps were the development of tracheal breathing and, after this, gill breathing. Pulmonary breathing is the most sophisticated method.