The document defines invertebrates as animals without backbones that are usually smaller than vertebrates and make up most animals on Earth. It classifies the major groups of invertebrates as jellyfishes, molluscs, arthropods, worms, and sponges. Molluscs such as snails and octopuses have soft bodies and some have shells, while arthropods like insects and arachnids have segmented bodies and are the largest invertebrate group.

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.