More than 95% of the Earth's animal species are invertebrates (animals without backbones). They can be found in most habitats. Many are found only in the sea and some groups living on the land are found world-wide. There are thought to be between 3 million and 15 million species in the world (47 000 species of vertebrates).

Invertebrates are important in the functions and processes of most ecosystems. They are spectacular, abundant and diverse. They include the Giant Squid at 18m long and gall mites, which are less than .25mm long.

The Australian Museum holds extensive invertebrate collections and conducts research in specialised areas.