How do you catch them?

To collect the types of bacteria we have been looking at, start by looking at a nearby body of water, preferrably natural. Look for a region with black coloured sand, or a region with black coloured sand just underneath some other type of sand. It's bad smell may help you find these spots, however the soil does not have to smell bad for it to be suitable. Experience tells us that the bacteria seem to prefer salty, undisturbed water. The presence of plants or photosynthetic algae or bacteria (as indicated by their green colour) is usually a bad sign, as these organisms produce oxygen. If the local oxygen level of the water is too high, it may kill the bacteria.

To collect the samples, it is best to use a small glass jar or glass fruit-juice bottle with a lid. A container that can hold 300 - 500 ml is ideal. Scoop soil and water into the container, ensuring the sample contains soil from all parts of the first inch or two of the sand. We are not entirely sure exactly where abouts the bacteria reside. You should aim to fill the bottle 1/3 to 2/3 with soil, with the remained being the water around the sample. When you take the container out of the water, fill it to the brim by using your lid to scoop more water into it. Place the lid on the jar loosely, to enable a small amount of oxygen to interact with the ecosystem. It is a good idea to label your sample and record some information about it- you may wish to return to a good site, or monitor the effect of seasonal or environmental changes on magnotactic bacteria populations.

See us on safari at Rottnest Island, September 2000 here .