A puppy, a goldfish and a bird all look very different. But they need the same four things to stay alive.
Key idea
Animals need food, water, air and shelter, a safe place to rest and hide.
Why it works
Food gives an animal energy to move and grow. Water keeps its body working. Air has oxygen, which every animal's body uses. Shelter keeps it safe from bad weather and from animals that might eat it.
Worked example: Let's think it through
A fish lives under water. Does it need oxygen?
- Every animal needs oxygen.
- A little oxygen is mixed into the water.
- A fish's gills take that oxygen out of the water as it flows past.
Answer: Yes. A fish gets its oxygen from the water with its gills.
Common mistake
Many children think only land animals need air. Fish need oxygen too; they take it from the water. Whales and dolphins swim up to the surface to breathe air, just like us.
For the grown-up. This builds on What Living Things Need. A goldfish bowl is a good example: the water needs to stay clean and have oxygen in it, which is why many fish tanks have a bubbler.