---
title: "What Animals Eat"
book: "Primary & Middle School Biology"
subject: biology
language: en
chapter: 10
exercises: 10
source: https://one-course.com/books/biology/1/en/chapter/10-what-animals-eat
---

# Chapter 10 — What Animals Eat

The rabbit in the meadow nibbles grass all day. The fox that crosses the same meadow at dusk is not interested in grass at all — it is interested in the rabbit. And the blackbird takes worms in the morning and cherries in the afternoon. Every [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) must eat, but not every [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) eats the same things.

## 10.1 Three kinds of eaters

**Definition 10.1 (Herbivore, carnivore, omnivore).**

[Animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) are sorted by what they eat:

- a *herbivore* eats [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) : grass, [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) , [seeds](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) , fruit — the rabbit, the cow, the snail;
- a *carnivore* eats other [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) : the fox, the cat, the ladybug (which hunts tiny [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) lice);
- an *omnivore* eats both [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) and [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) : the blackbird, the wild boar — and humans.

**Example 10.2 (One meadow, three menus).**

In one summer meadow: the rabbit crops the grass ([herbivore](#def-g2-what-animals-eat-kinds)); the fox hunts the rabbit ([carnivore](#def-g2-what-animals-eat-kinds)); the blackbird takes a worm now, a cherry later ([omnivore](#def-g2-what-animals-eat-kinds)). Three neighbors, three menus — and notice that the fox’s dinner ate grass first.

![A herbivore at work: the rabbit and the meadow, blade by blade.](https://one-course.com/images/onecourse/chapters/biology-1/g2-what-animals-eat/img-42dde25d4742.jpg)

*A [herbivore](#def-g2-what-animals-eat-kinds) at work: the rabbit and the meadow, blade by blade.*

**Remark 10.3 (Carnivores are not villains).**

The fox is not “mean” for eating rabbits: hunting is simply how a [carnivore](#def-g2-what-animals-eat-kinds) feeds — as natural as the rabbit’s nibbling. In nature, eating and being eaten are part of how life works; a later chapter will hang all these meals together into food chains.

## 10.2 Reading an animal’s menu from its body

**Proposition 10.4 (Bodies match menus).**

An [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal)’s body carries clues about its food:

- [herbivores](#def-g2-what-animals-eat-kinds) like the rabbit and the cow have big flat cheek teeth for grinding [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) , and spend long hours eating;
- [carnivores](#def-g2-what-animals-eat-kinds) like the cat and the fox have pointed teeth for seizing prey, sharp claws, and forward-looking [eyes](https://one-course.com/books/biology/1/en/chapter/5-the-five-senses#def-g1-the-five-senses-sense) for hunting;
- birds show it in the beak: short and thick for cracking [seeds](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) (the sparrow), curved and hooked for tearing meat (the eagle), long and thin for picking insects from bark.

**Proof.** *Admitted at this level.* ∎

![Three beaks, three menus: the bird’s beak is a tool shaped by its food.](https://one-course.com/images/onecourse/chapters/biology-1/g2-what-animals-eat/img-7ed076b30065.jpg)

![Three beaks, three menus: the bird’s beak is a tool shaped by its food.](https://one-course.com/images/onecourse/chapters/biology-1/g2-what-animals-eat/img-52ef93cb3a9e.jpg)

![Three beaks, three menus: the bird’s beak is a tool shaped by its food.](https://one-course.com/images/onecourse/chapters/biology-1/g2-what-animals-eat/img-945c28b9d85b.jpg)

*short thick beak: cracks [seeds](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed)*

*hooked beak: tears meat*

*long thin beak: picks out insects*

*Three beaks, three menus: the bird’s beak is a tool shaped by its food.*

**Example 10.5 (The cat’s teeth).**

Watch a cat yawn: long pointed teeth at the front corners of its mouth. Those are seizing teeth — a [carnivore](#def-g2-what-animals-eat-kinds)’s equipment. The cow, yawning, would show none: her mouth is all wide, flat grinders for grass.

**Method 10.6 (Guessing a menu).**

To guess what an unknown [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) eats:

1. look at the teeth or the beak: flat grinders, pointed seizers, or both?
2. look at claws and [eyes](https://one-course.com/books/biology/1/en/chapter/5-the-five-senses#def-g1-the-five-senses-sense) : hunting tools, or not?
3. watch it feed if you can — the surest clue of all;
4. then name it: [herbivore](#def-g2-what-animals-eat-kinds) , [carnivore](#def-g2-what-animals-eat-kinds) or [omnivore](#def-g2-what-animals-eat-kinds) .

## 10.3 Eating enough, day after day

**Proposition 10.7 (Feeding is a daily task).**

Food is the body’s fuel and building material, so [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) must eat again and again, day after day. How much time it takes depends on the menu: grass gives little at each mouthful, so the cow grazes for hours; meat is rich, so the fox may eat one good meal and rest.

**Proof.** *Admitted at this level.* ∎

**Example 10.8 (Winter changes the menu).**

Food changes with the seasons. The blackbird eats worms and insects in summer, but in winter, when the ground is hard, it switches to berries. An [omnivore](#def-g2-what-animals-eat-kinds)’s wide menu is a great help when times get hard.

## 10.4 Exercises

**Exercise 10.1 ★.**

Give the words for: an [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) that eats [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant); an [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) that eats other [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal); an [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) that eats both.

**Solution of Exercise 10.1.**

[Herbivore](#def-g2-what-animals-eat-kinds); [carnivore](#def-g2-what-animals-eat-kinds); [omnivore](#def-g2-what-animals-eat-kinds).

**Exercise 10.2 ★.**

[Herbivore](#def-g2-what-animals-eat-kinds), [carnivore](#def-g2-what-animals-eat-kinds) or [omnivore](#def-g2-what-animals-eat-kinds): (a) the cow; (b) the fox; (c) the blackbird; (d) the snail; (e) the human?

**Solution of Exercise 10.2.**

(a) [Herbivore](#def-g2-what-animals-eat-kinds). (b) [Carnivore](#def-g2-what-animals-eat-kinds). (c) [Omnivore](#def-g2-what-animals-eat-kinds). (d) [Herbivore](#def-g2-what-animals-eat-kinds). (e) [Omnivore](#def-g2-what-animals-eat-kinds).

**Exercise 10.3 ★.**

Which teeth does a [herbivore](#def-g2-what-animals-eat-kinds) need most: flat grinders, or pointed seizers? Why?

**Solution of Exercise 10.3.**

Flat grinders — [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) like grass are tough and must be ground for a long time before swallowing; there is no prey to seize.

**Exercise 10.4 ★.**

Match each beak with a menu: short and thick; curved and hooked; long and thin.

**Solution of Exercise 10.4.**

Short and thick: cracking [seeds](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed). Curved and hooked: tearing meat. Long and thin: picking insects out of bark and crevices.

**Exercise 10.5 ★.**

The ladybug is small, pretty — and a [carnivore](#def-g2-what-animals-eat-kinds). What does it hunt?

**Solution of Exercise 10.5.**

Tiny [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) lice (aphids) — the ladybug eats great numbers of them, which makes gardeners love it.

**Exercise 10.6 ★.**

Why does the cow spend many more hours eating than the fox does? Use [Proposition 10.7](#prop-g2-what-animals-eat-daily).

**Solution of Exercise 10.6.**

Grass gives little nourishment at each mouthful, so the cow must graze for hours to get enough; meat is rich, so one good meal can last the fox a long while.

**Exercise 10.7 ★.**

What does the blackbird eat in summer, and in winter? Why is a wide menu useful?

**Solution of Exercise 10.7.**

Worms and insects in summer; berries in winter, when the ground is too hard for worms. A wide menu lets an [omnivore](#def-g2-what-animals-eat-kinds) switch foods when one runs out — a great help in hard seasons.

**Exercise 10.8 ★.**

Try it: watch birds in a park or at a feeder. Note what each kind takes — [seeds](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed), bread, insects, berries — and look at their beaks. Does [Proposition 10.4](#prop-g2-what-animals-eat-match) hold?

**Solution of Exercise 10.8.**

Open answer. Typically: sparrows and finches (short thick beaks) take [seeds](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed); tits pick insects and [seeds](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed); blackbirds probe for worms and take berries. The beak–menu match of the proposition holds well.

**Exercise 10.9 ★★.**

A zoo receives a mystery [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal): pointed front teeth, sharp claws, [eyes](https://one-course.com/books/biology/1/en/chapter/5-the-five-senses#def-g1-the-five-senses-sense) facing forward. What is its likely menu? Which steps of [Method 10.6](#met-g2-what-animals-eat-guess) did you use?

**Solution of Exercise 10.9.**

A [carnivore](#def-g2-what-animals-eat-kinds)’s menu: other [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal). Steps 1 and 2 — the teeth (pointed seizers) and the hunting tools (claws, forward [eyes](https://one-course.com/books/biology/1/en/chapter/5-the-five-senses#def-g1-the-five-senses-sense)); step 4 named it.

**Exercise 10.10 ★★.**

“Without grass there would soon be no foxes.” The fox never eats grass — yet the sentence is right. Explain, using the meadow of [Example 10.2](#ex-g2-what-animals-eat-meadow).

**Solution of Exercise 10.10.**

The fox eats rabbits, and rabbits eat grass. No grass, no rabbits; no rabbits, hungry foxes. The fox depends on grass *through* its prey — meals in nature form chains.