Invertebrates are animals without a backbone. They can be further divided into three groups that share similar characteristics: insects, arachnids and molluscs.
key characteristics
examples
Insects
Six legs and three body parts.
Butterflies, beetles, ants and houseflies.
Arachnids
Eight legs and two body parts.
Scorpions and spiders.
Molluscs
Slimy foot and sometimes have a shell.
Snails, slugs and squids.
Classification key
Classification keys can help identify animals. The below classification key can be used to identify the three groups of invertebrates.