We need food to grow, right? The food we eat contains the nutrients that our bodies need to replace worn out cells, stay healthy and stay strong. It is the same for every living organism. Food comes in many different forms, and plants and animals have special organs or parts that absorb the goodies from the food we eat.
Plants use sugars, fats and proteins to grow and stay healthy. They produce these themselves with the help of sunlight, water and carbon dioxide. The nutrients produced are stored in the plants and the nutrients are passed on to other animals that eat these plants.
When living things die and rot in the ground, the nutrients in them end up in the soil and get dissolved in it. As a result, plants roots are able to absorb nutrients such as salts, potassium, minerals, starch, phosphates and nitric acids from soils too.
Animals also need food or nutrients to survive. They get nutrients from eating plants.
Bigger animals eat other smaller animals for food. Aquatic animals (such as fish) eat tiny water insects, worms and plankton.
In some cases, organisms such as fungi, get their food by breaking down nutrients in organic matter (once-living things). (click here to see the lesson on 'Nutrients in food') All these contain some specific nutrients that the animals need to grow healthy.