Finding and catching food
No animal can live without food. Food contains the building blocks of life, including proteins for growth, minerals for health and starch for energy.
The way animals are built
The way an animal behaves and the shape of its body – especially its mouthparts – gives you a clue about its diet. Scientists group animals into different types according to what they eat.
Veggies, big and small
Animals that eat only plants are called herbivores. Each has a body designed for its diet. For instance, a caterpillar’s mandibles (its mouth) are perfect for chewing a leaf, while a red deer has strong molar teeth for grinding down grass and a four-chambered stomach to digest it.
Animals that only eat other animals are called carnivores. They have deadly skills and equipment for killing. Spiders use a sticky web to trap insects and a poisonous sting to finish them off. Stoats use stealth to catch a rabbit, and sharp teeth for the killing bite.
One look at a bird’s bill can tell you what it eats. Seed-eaters, such as greenfinches, have short, thick bills for crushing seeds. Insect-eaters, such as robins, have finer bills for snapping up insects. A kingfisher’s dagger bill is perfect for spearing fish, while the sharp hooked bill of a buzzard can rip a rabbit apart. Try playing our game ‘The Bill Please, Waiter’ to see if you can match different birds with their food.
Best of both worlds
Some birds change their feeding habits as their food supplies change. Blue tits, for instance, can eat insects in summer, berries in autumn and seeds in winter. Animals that feed on both plants and animals are called omnivores. They include beetles, badgers and – you’ve guessed it! – people. A crow is an omnivorous bird. Its multi-purpose bill can pluck fruit, crack eggs, split seeds, pull up worms and even tear open a dead animal.
Animals can’t make their own food like plants do. So they have to eat other organisms instead. Plants have already done the hard work. The food they have made is now ready for animals to take away. Animals that eat plants are called primary consumers, because they are the first (primary) consumers in the food chain.
Many animals feed only on plants. Some insects, such as caterpillars, eat leaves. Others, such as aphids, suck plant juice, called sap. Small mammals, such as mice or squirrels, nibble nuts and berries. Larger ones, such as rabbits and deer, may graze on grass.
Many birds eat plants. Some, such as finches or pigeons, eat mostly seeds or grain. Others, such as blackbirds, enjoy fruit and berries. A few, such as jays, can tackle hard nuts like acorns. Few birds eat leaves. They prefer the more nutritious parts of plants, such as seeds and fruit, which give them extra energy for flying.
Food from a plant does not come in a form that suits an animal’s needs. So the animal’s body breaks the food down into simpler substances - such as starch into sugars and proteins into amino acids. This is what happens in digestion; you’re probably doing it right now! The animal can then use these substances to keep active and alive and to build materials that help its own body to grow.
Not every animal has a taste for plants.
Many get their food by eating other animals. These animals are called secondary consumers, because they are the second consumer step in the food chain.
Animals that eat secondary consumers are called tertiary (third) consumers, because they are the third consumer step in the food chain.
This woodland food chain shows how the different consumers are linked.
The caterpillar eats a plant, so it is a primary consumer. The blue tit eats the caterpillar, so it is a secondary consumer. The sparrowhawk eats the blue tit, so it is a tertiary consumer.
Nearly every kind of animal makes a meal for some kind of bird. Flycatchers snap up flies, kingfishers spear fish and kestrels swoop on mice. Of course birds are animals too, so many of them may also end up as someone else’s dinner. Weasels, snakes and foxes all eat birds – and so do other birds, including hawks, owls and gulls.
A bird’s position in the food chain may vary according to what it eats. For instance, when a blue tit eats seeds it is a primary consumer. But when it eats a caterpillar, it is a secondary consumer because the caterpillar has already eaten a plant.