Year 6 Science · Classifying living things · Lesson 2.3

Year 6 Science: Animals with and without a backbone

Part of the Year 6 Science classifying living things chapter. Chapter overview · whole chapter on one page

2.3

Animals with and without a backbone

Year 6
LH1: living things are classified into broad groups by common observable characteristics, including animals, LH2: give reasons for classifying animals based on specific characteristics

Story. A class visits a farm. Mo sees a hen, a cow, a frog in a pond and a spider in a corner. “Why is the frog in one group and the spider in another?” he asks. The farmer says, “Look for a backbone first.”

Animals are sorted into two big groups: those with a backbone and those without.

Animals with a backbone are vertebrates. These are fish, amphibians, reptiles, birds and mammals.
Animals without a backbone are invertebrates. Insects, spiders and worms are examples.

Each vertebrate group has its own characteristics, such as scales, feathers or hair. Invertebrate groups are sorted using features such as the number of legs.

Simple drawings of six animals: a fish, a frog, a lizard, a bird, a dog and an ant. Not to scale.

The table gives the characteristics of each group.

Group	What the group members have
Fish	live in water, have fins and gills, usually have scales
Amphibians	live on land and in water, have moist skin, usually lay eggs in water
Reptiles	have dry scaly skin, usually lay eggs with a leathery shell on land
Birds	have feathers and a beak, lay eggs with hard shells
Mammals	have hair or fur, most give birth to live young, feed their young on milk
Insects	have six legs and three body parts
Spiders	have eight legs and two body parts
Worms	have no legs and a soft body

A spider with eight legs and a worm with no legs. Neither has a backbone.

Key ideas

Vertebrates have a backbone: fish, amphibians, reptiles, birds and mammals.
Invertebrates have no backbone: insects, spiders and worms are examples.
Birds have feathers and beaks. Mammals have hair or fur and feed their young on milk.
Insects have six legs; spiders have eight legs; worms have no legs.

Worked example 2.3.1

Look at the table in section 2.3. Which group has feathers and a beak? Write the group.

Method. Find the group with feathers.

Read the table. The birds have feathers and a beak.
feathers and a beak
Write the group. So the group is birds.
birds
Write the answer.
birds

Check. Birds are vertebrates, because they have a backbone. ✓

Worked example 2.3.2

Look at the table in section 2.3. Which group has dry, scaly skin? Write the group.

Method. Find the group with dry, scaly skin.

Read the table. The reptiles have dry, scaly skin.
dry, scaly skin
Write the group. So the group is reptiles.
reptiles
Write the answer.
reptiles

Check. A snake and a lizard are both reptiles. ✓

Worked example 2.3.3

An ant has six legs and no backbone. Which invertebrate group is it in? Write the group.

Method. Find the invertebrate with six legs.

Read the table. The table says an insect has six legs and three body parts.
six legs
Write the group. So an ant is an insect.
insects
Write the answer.
insects

Check. An ant has six legs and no backbone, so it is an invertebrate. ✓

Watch out

Watch out: an animal that flies is not always a bird. A bird has feathers and a backbone, but an insect can fly and has no backbone.

Exam tip

Exam tip. Start with the backbone: if there is one, the animal is a vertebrate, and then use the other characteristics to name its group.

Try it (with your teacher, or a grown-up at home). Look at pictures of five animals from books or a safe website, with a grown-up. Write down whether each one has a backbone. Then say which group each vertebrate belongs to, using feathers, fur, scales or moist skin. Do not touch wild animals or insects.