Invertebrates are animals without backbones. They make up most species on Earth and live on land and in water. The document classifies and describes key invertebrate groups: molluscs like mussels have soft bodies and some have shells; arthropods like insects and arachnids have segmented bodies; worms have long soft bodies and some live underground or in water; jellyfish live in water and have soft bodies and stinging tentacles; sponges live in water and have pores but never move.

1. Invertebrates

2. What is an invertebrate?
Invertebrates don’t have a
backbone.
They are usually smaller than vertebrates.
Most animals on earth are invertebrates.
Some live on land and some live in water.
Some can fly.

3. Classifying invertebrates
The most important groups are:
Jellyfishes or sea jellies
Molluscs
Arthropods
Worms
Sponges

4. Molluscs
Molluscs have a soft body.
Some, like snails, have a
shell. Some of them, do not
have a shell.
Many molluscs live in the sea.
Mussels, squids and
octopuses are all molluscs.

5. Arthropods
Arthropods are the
biggest group of
invertebrates.
Their bodies are divided
into 3 parts.
Insects (ants and bees)
and arachnids (spiders
and scorpions) are
arthropods.

6. Worms
Worms have a long,
soft body.
Some live underground
and others live in water.
Some worms can live in
human bodies. They
make us ill.

7. Jellyfishes
or sea jellies
Jellyfishes live in
water.
They have soft
bodies and
tentacles.
They don't have
fins.
Be careful! Their
tentacles can sting
you!

8. Sponges
Sponges live in water.
They have holes
(pores).
They never move.