Book 6, Question 26
Why Do Fish Have Gills?
Fish pull oxygen out of the water with thin gill tissues. We air-breathers use lungs instead. It is the same job with a different tool.
From the book
Page from A Million Whys Book 6
More fun facts
- Fish use gills to take oxygen out of the water.
- Water holds only small amounts of oxygen, so fish need a special system to collect it.
- Water flows in through a fish's mouth, over the gills and out under a flap called the operculum.
- West African lungfish have both gills and a simple lung.
- Frogs start life as tadpoles with gills like fish and grow lungs as adults.
- A frog's skin is so thin that it can soak up oxygen.
Sources: National Geographic, BBC, BBC
Questions kids ask
Do fish have lungs?
Most fish do not. They use gills, though a few, like lungfish, also have a simple lung.