All animals need oxygen to live, but they do not all breathe the same way. Different animals use different respiratory organs to take in oxygen from the air or from water.
Main respiratory organs
- Lungs — used by humans, cats, dogs, birds and whales.
- Gills — used by fish and prawns to take oxygen from water.
- Moist skin — used by earthworms and frogs; oxygen passes through the wet skin.
- Breathing tubes (tracheae) — tiny tubes used by insects like grasshoppers.
Key idea
Land animals often use lungs. Water animals like fish use gills. Some animals use more than one respiratory organ.
Example
A frog uses gills as a tadpole living in water. When it grows into an adult on land, it breathes using its lungs and its moist skin.
Remember
- Whales live in water but breathe air with lungs, so they come up to the surface.
- An earthworm must keep its skin moist so it can breathe.
- The respiratory organ helps the animal survive in its home.