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Exalted status for the humble earthworm

August 28, 2002

In the week following the Earth Summit in Johannesburg, international attention will be focused on Cardiff and the ecological importance of earthworms in temperate and tropical ecosystems. Considered sacred by Cleopatra, earthworms undoubtedly promote the sustainability of soils.

The earthworm's status as one of the world's most crucial organisms is why scientists from 40 countries will congregate at Cardiff University next week for the International Symposium on Earthworm Ecology (1-6 September 2002).

More than 3,000 species of earthworm exist in the world - although only 25 species exist in Britain, and some 300 species in Europe. They all play an important role in forest or agricultural ecosystems and they play an increasing role in biomedical issues as, for example, a replacement for animals in medical experiments and chemical testing.

Subtitled "From Darwin to Microsatellites", the conference not only revisits Darwin's extraordinary monograph on earthworms, published in 1881, but it will also focus on new avenues of research and shed light on how worm biodiversity can be exploited to improve human and environmental health and create economic wealth. Themes to be covered at the symposium include: temperate and tropical biodiversity; organic-wasted treatment; applied molecular genetics; environmental toxicology; sustainable agriculture; and land reclamation.

"The ordinary earthworm may seem an unlikely candidate for one of the world's 'keystone organisms' but in reality it is a complex creature," said conference organiser Dr John Morgan, of Cardiff University's School of Biosciences. "Literally thousands of scientists worldwide consider the earthworm to be an important ally in advancing environmental and biomedical research."

Earthworms are critical to the environment because they consume huge quantities of decomposed litter, manure, and other organic matter deposited on soil - helping to convert it into rich topsoil. The casts excreted by earthworms form clumps of soil particles bound together by organic compounds that improve soil structure, retain nutrients that might otherwise be leached, and reduce the threat of erosion.

Earthworms can also help reduce soil compaction, improve permeability - thus providing channels for root growth, water infiltration, and gas exchange.

"These attributes will unquestionably be harnessed in the future for the sustainable management of organic wastes, yielding valuable composts and generating wealth in an environmentally friendly way," said Dr Morgan.

Earthworms are also important animals for the assessment of the toxicity of chemicals, such as herbicides and pesticides, which are deliberately released into the environment. All EC member states now use standard earthworm tests to evaluate the potential toxicities of all newly synthesised chemicals - whether they are intended for direct release into the environment or not. Current research focuses on the immunology and genetic makeup of earthworms in an effort to produce more sensitive and reliable diagnostic tests, which can be applied to worms in their native environments.

"We find that earthworms are superb 'barometers' or 'sentinels' providing an early warning of deterioration in soil quality. This is important for protecting the health of natural environments, and of increasing interest in the context of protecting human health," said Dr Morgan.

Apart from being very successful animals, earthworms are also very complex. They possess, for example, a centralised nervous system. They also have blood vessels and a blood pigment, haemoglobin, much like a human being.

"One could go on to mention the urine-producing tubes that resemble kidney tubules, the liver-like tissue with truly remarkable capabilities for storing and rendering harmless a number of toxic chemicals, and of course the well-recognised but poorly understood ability to repair wounds and replace damaged body parts," said Dr Morgan.

"All of these functions make earthworms excellent biological tools for studying fundamental aspects of human conditions, from development to ageing, and from blood disorders to inflammatory diseases, such as rheumatoid arthritis."

Amongst the countries represented at the International Symposium on Earthworm Ecology are: Cameroon, India, Poland, Belarus, China, Japan, Brazil, Nigeria, Australia and the USA. Full details about the symposium are on the web at: www.cardiff.ac.uk/biosi/worm2002.

Society of Chemical Industry