Photo of a nematode - Psammomermis sp.

A nematode: Psammomermis sp.

Roundworm (Nematoda) research at CSIRO

Roundworm (Nematoda) research carried out at the Australian National Insect Collection (ANIC) has important implications for soil, plant and animal health.

  • 2 February 2009 | Updated 28 March 2013

Nematodes are mostly small, worm-like organisms that are not insects, but belong in a separate phylum, Nematoda. Most are between 1 and 2 mm long, although they range in length from 0.1 mm to nearly 10 m. They vary in thickness from about 5 µm to 2.5 cm.


Nematodes are the most abundant and ubiquitous multicellular organisms on earth. Estimates of the number of species range from 100 000 to over 1 000 000. In Australia about 1 000 named species are known, but this represents only a few per cent of the total. They may be small, but there are an awful lot of them. The total number of nematodes on earth is about 10 to the power 22 (10 thousand billion billion).

They are found everywhere, from the bottom of the oceans to near the tops of the highest mountains, from the tropics to polar regions, and in every other conceivable habitat.

By far the largest numbers of nematodes are in soil or sediments and are free-living. These nematodes eat microbes, other nematodes, microscopic animals or fungi. These nematodes are mostly beneficial, greatly enhancing nutrient cycling, assisting in degradation of wastes and able to be used as biological indicators.

Nematodes and other organisms

Some nematodes attack the roots, the stem, or the leaves of plants. Some transmit plant viruses, while others cause galls on the plant. Others burrow into the plant, and they often carry pathogenic fungi. 

Nematoda research is focused on taxonomy and classification of major groups of economic and environmental importance.

Nematodes are also found in or on most other types of organisms, from earthworms, insects, and molluscs, to fish, reptiles, birds and mammals, including humans. They can be:

  • parasites, living off the body of their host
  • commensals, sharing food with their host
  • phoretics, using their host for transport.

Some nematodes have only one host, while others have several during their life cycle.

Nematodes can also be vectors for bacteria or viruses.

Current projects

Interactive illustrated identification keys to nematodes of Australia
This project is producing keys to all nematodes in Australia at various taxonomic levels.

Curation & development of a national nematode collection
This project aims to develop and maintain collections of nematode pests of cereals in Australia.

Systematics of the nematode order Aphelenchida
This project has produced an annotated checklist to assist efforts to identify and differentiate local species from exotics.

Systematics of Australian nematodes
This project is describing and documenting nematode species from Australia which are of particular economic, ecological or quarantine interest.

Find out more about CSIRO's work in Biodiversity.