About invertebrates    

Janet Farr in the field. Image - Parks and Wildlife
Janet Farr in the field - Photo © Parks and Wildlife

The collective term for animals without backbones is 'invertebrates'. Invertebrates include jellyfish, worms, crustaceans, insects, coral, sponges and molluscs. They make up more than 95 per cent of all living animal species and occur in almost every terrestrial, marine and freshwater habitat apart from the extreme polar regions and very high mountain peaks.

Invertebrates vary in size, from the very small (flat worms, nematodes, collembolla and ostracods) to the very large (giant squid). To date, scientists have documented 1.7 million invertebrate species, but they estimate numbers could range between 10-30 million. In comparison there are only 40 000 - 50 000 known vertebrate species. Up to 20,000 new invertebrates are documented every year. Unfortunately, species numbers are declining faster than scientists can record their existence.

Australia has 100 000 documented, and an estimated 200 000 undescribed invertebrate species. This compares with 6000 vertebrate species. Most Australian invertebrates do not occur anywhere else in the world. 

Invertebrates perform vital roles in every ecological system on earth:

  • Invertebrates are an essential component of most food webs.
  • They both consume and are consumed by plants and other animals.
  • Invertebrates recycle organic matter, putting it back into circulation for use by other parts of the ecosystem.
  • Invertebrates assist in the transmission of disease.
  • Invertebrates cross-pollinate flowers.
  • Invertebrates are instrumental in controlling the numbers of other species.


Western Australia’s invertebrates

Invertebrates make up most of the biodiversity of Western Australian species. Of the documented Western Australian invertebrate species, five are extinct and over 80 are rare or at risk of extinction. Western Australia has a high diversity of subterranean invertebrates. These are animals that live underground either in air spaces (troglofauna) or in groundwater (stygofauna). Parks and Wildlife’s Pilbara Region Biological Survey has shown that there are more than 350 species of stygofauna in the Pilbara.

The major threats to invertebrates in Western Australia are habitat destruction, salinity, Phytophthora dieback, introduced invasive invertebrates, and lack of scientific knowledge.

Parks and Wildlife invertebrate research

Research on invertebrates aims to increase our knowledge about insect habitats and ecology. Much of the focus is on the impact of human activities and fire on the biodiversity of invertebrates. Other research includes monitoring the impact of destructive native pests on our jarrah forests. These pests include the jarrah leafminer (Pertida glyphopa) and the Gumleaf skeletonizer (Uraba lugens). Invertebrate research is a component of many of our larger biodiversity monitoring projects. These include FORESTCHECK (Invertebrate component) and the Pilbara Region Biological Survey.

View the department’s Science Information Sheets for more projects.

Related resources

Landscope Articles

Staff publications

BugBase is a database of the Department's Forest Insect Reference Collection, composed mainly of specimens of beetles, butterflies and moths.

Common Butterflies of the South-West 
This Parks and Wildlife bush book describes some of the butterflies found in the south-west of Western Australia.

Bugs in the Backyard
This Parks and Wildlife bush book describes some of the invertebrates found in gardens, homes and other buildings in Western Australia.

Threatened Animals of Western Australia  
This important book by eminent naturalist and scientist Andrew Burbidge, documents the current state of research into, and management of threatened animals in Western Australia; looks at the factors that led to their decline; and presents a vision of what needs to be done to conserve WA's amazing biodiversity.

Walpole Wilderness Invertebrate Fire Research Project
Following the March 2001 wildfire in the Nuyts Wilderness, a large group of local volunteers from the Walpole Community and Walpole Nornalup National Parks Association have been trapping and inventorying the litter arthropod species of these forest sites, as well as long unburnt sites nearby. This website records their findings.

Western Australian Museum 
Information on the WA museums, entomology research and collection

WA Department of Agriculture and Food 
Information about insect pests in Western Australia

Australian Museum Factsheets 
Fact sheet about Australian insects

CSIRO Entomology

Western Australian Insect Study Society


 For further information on Parks and Wildlife invertebrate research, contact Dr Janet Farr