Biologists know that most species are not easily seen. In fact, based on the number of species we already know, scientists estimate that many more species remain to be discovered. New ones are being found as fast as scientists look for them. Most undescribed species are small and occur in soil, tropical rainforests and marine habitats. Extinction is probably already affecting these 'hidden' species. Many small organisms are important. For example, the living things in soil carry out all sorts of useful services such as decomposition, nutrient cycling and creation of good soil structure. Human activities – such as cultivation and the use of fertilisers, herbicides and pesticides – may all affect what lives in soil. For example, it is becoming clear that the increasing acidification that is a problem in several parts of the country is bad for the nitrogen-fixing bacteria that are so important to the growth of many crops and native plants. Many species still to be studied Below the soil, in regions of the Earth's crust once considered to be of interest only to geologists, life is also turning up. Bacteria have been discovered that thrive in near-boiling mineralised water or live immersed in hot oil hundreds of metres below the ground. Not much is known about the 'hidden' species in Australia. Biologists estimate that there must be at least 225,000 species of invertebrates here, but only half that number have even been described, let alone studied in detail. As life here has evolved in relative isolation for tens of millions of years, many of these invertebrates are not found anywhere else. Even less is known of our fungi and microbes. Other boxes Box 3. Australia's biodiversity Box 4. The mathematics of reserve systems Box 5. Survival of the cutest?
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Posted April 1997.
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