Protozoa is the name given to the whole group of single-celled animals. All protozoa are very tiny, and most are able to move about, usually by means of beating hairs which are called cilia. Protozoa do not have any organs, but regions inside their jelly-like body have special functions, such as feeding and catching prey. Some protozoans are parasites and can cause diseases such as dysentery and malaria.
Most protozoa are aquatic, because they do not have an outer coat to keep them from drying out. Protozoa can be found living in every puddle you see, feeding on bacteria and debris.
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