Rain puddles may look as if they contain only clear rainwater, but they also contain millions of tiny organisms. Most of these are too small to be seen with the naked eye. Microscopic plants and animals lie in the dust, where they are protected inside spores to stop them drying out. These organisms will resume their life within a few hours of rain falling, and if the puddle lasts, it will be teeming with life within one or two days.
Much of this microscopic life consists of algae and single-celled animals which are called protozoa. It also contains rotifers, which are very tiny animals with complicated feeding arms that eat the other, smaller organisms.
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