Year 3 Science: Skeletons in other animals
Part of the Year 3 Science skeletons and muscles chapter. Chapter overview · whole chapter on one page
Skeletons in other animals
Humans are not the only animals with a skeleton. Many animals have a skeleton inside their body, made of bones. Dogs, horses, birds and fish all have bones inside their bodies.
Some animals have no bones inside their body. Snails, slugs and jellyfish have soft bodies and no bones inside them.
This table shows some animals, and whether each one has a skeleton inside its body:
| Animal | Skeleton inside the body? | What it is like |
|---|---|---|
| human | yes | bones inside the body |
| dog | yes | bones inside the body |
| horse | yes | bones inside the body |
| bird | yes | bones inside the body; many bird bones are hollow, which keeps them light |
| fish | yes | a skeleton inside the body |
| snail | no | a soft body, with no bones inside |
| slug | no | a soft body, with no bones inside |
| jellyfish | no | a soft body, with no bones inside |
Scientists sort things into groups based on their features. Sorting animals into a yes group and a no group is one simple way to do this.
Key ideas
- Humans and some other animals have a skeleton inside the body.
- Dogs, horses, birds and fish have bones inside their bodies.
- Snails, slugs and jellyfish have no bones inside their bodies.
- Sorting into a yes group and a no group is a simple way to classify animals.
Method. Find the dog in the table.
- Read the table. The table says a dog has bones inside its body.yes
- Write the answer. So a dog has a skeleton inside its body.yes
- Write the answer. yes
Check. Dogs have bones inside their bodies. ✓
Method. Find the snail in the table.
- Read the table. The table says a snail has a soft body, with no bones inside.no bones
- Write the answer. So a snail does not have bones inside its body.no
- Write the answer. no
Check. A snail has no skeleton of bones. ✓
| Sorted group | Tally | Number of cards |
|---|---|---|
| yes: has a skeleton inside | ||||| || | 7 |
| no: no bones inside | ||| | 3 |
| all cards | 10 |
Method. Read the tally for the yes group.
- Read the tally. The yes group has the tally ||||| ||.||||| ||
- Read the number. The number of cards in the yes group is 7.7
- Write the answer. 7
Check. 7 yes cards and 3 no cards make 10 cards in all. ✓
Watch out. Count the strokes in the tally. Groups of five are written with a space between them.
Watch out
Watch out: a snail has no bones inside its body, even though it has muscles. An animal can have muscles and still have no skeleton of bones.
Try it at home or school (with a grown-up). With a grown-up, look at a picture of a dog and a picture of a snail in a book, or on a safe website. Which one has bones inside its body? Do not touch wild animals. Wash your hands afterwards.
Exam tip
Grown-up tip. Ask: “Which of these animals has bones inside? How could you tell?” Let your child sort five pictures into a yes group and a no group.
Exercise 6C Skeletons in other animals
Method. Find the horse in the table.
- Read the table. The table says a horse has bones inside its body.yes
- Write the answer. yes
Check. Horses have a skeleton inside their bodies. ✓
Method. Find the snail in the table.
- Read the table. The table says a snail has no bones inside its body.no
- Write the answer. no
Check. A snail has a soft body. ✓
Method. Look at the dog and the jellyfish in the table.
- Read the table. The dog has bones inside its body. The jellyfish has a soft body with no bones inside.jellyfish
- Write the answer. jellyfish
Check. The jellyfish has no bones inside. ✓
Method. Look at the yes rows in the table.
- Read the table. The yes rows are the human, dog, horse, bird and fish.human, dog, horse, bird, fish
- Write the answer. Accept any two of: human, dog, horse, bird, fish.
Check. Five animals in the table have bones inside. ✓
Method. Look at the picture of each animal.
- Look at the fish. The fish has its skeleton drawn inside its body.fish
- Look at the snail. The snail has no bones inside its body.not the snail
- Write the answer. fish
Check. A fish has a skeleton inside its body. ✓
| Sorted group | Tally | Number of cards |
|---|---|---|
| yes: has a skeleton inside | ||||| || | 7 |
| no: no bones inside | ||| | 3 |
| all cards | 10 |
Method. Read the yes row in the tally table.
- Read the row. The yes row has 7 in the number column.7
- Write the answer. 7
Check. 7 cards have a skeleton inside. ✓
| Sorted group | Tally | Number of cards |
|---|---|---|
| yes: has a skeleton inside | ||||| || | 7 |
| no: no bones inside | ||| | 3 |
| all cards | 10 |
Method. Read the no row in the tally table.
- Read the row. The no row has 3 in the number column.3
- Write the answer. 3
Check. 7 + 3 = 10. ✓
| Sorted group | Tally | Number of cards |
|---|---|---|
| yes: has a skeleton inside | ||||| || | 7 |
| no: no bones inside | ||| | 3 |
| all cards | 10 |
Method. Read the all cards row in the tally table.
- Read the row. The all cards row says 10.10
- Write the answer. 10
Check. 7 + 3 = 10. ✓
Method. Think about the frame of bones inside an animal.
- Read the sentence. Humans and dogs have a skeleton inside their body.skeleton
- Write the answer. skeleton
Check. A skeleton is a frame of bones. ✓
Method. Think about what snails and slugs do not have.
- Read the sentence. Snails and slugs have no bones inside their body.bones
- Write the answer. bones
Check. Snails and slugs have soft bodies. ✓
Method. Look at the jellyfish in the table.
- Read the table. The jellyfish has a soft body, with no bones inside.no bones
- Write the answer. false
Check. A jellyfish has no bones inside its body. ✓
Method. Look at the fish in the picture and the table.
- Read the table. The fish has a skeleton inside its body.skeleton inside
- Write the answer. true
Check. The fish in the picture has its skeleton drawn inside. ✓
Method. Think about muscles and bones.
- Think about bones. A snail has no bones inside its body.no bones
- Think about muscles. Having no bones does not mean an animal has no muscles.muscles are different
- Write the answer. No. Accept any reason that says a snail can have muscles even though it has no bones.
Check. Muscles and bones are different parts of the body. ✓
Method. Think about what the question is asking.
- Think about the question. The question asks about bones inside the body, not the colour.bones inside
- Decide. So sorting by colour does not answer the question. Sort by whether the animal has bones inside.sort by bones
- Write the answer. No. Accept any reason that says colour does not show whether an animal has bones inside its body.
Check. A fair sort looks at the feature being tested. ✓
Method. Think about the jobs of the skeleton and of the muscles.
- Think about support. The skeleton holds the horse up and gives it its shape.support
- Think about movement. Muscles pull on the bones, so the horse can run.movement
- Write the answer. Accept any sentence that says the skeleton supports the horse, and muscles pull on the bones to make it move.
Check. The skeleton and the muscles work together. ✓