All I know is that it's a really, really small organism, it looks terrifying (to me at least), and it can survive just about any environment. What do they do and should I have any reason to avoid/be afraid of them?
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They don't "do" anything. They're just microscopic animals that are strangely able to withstand the most extreme environmental conditions possible.
They can live in water well past the boiling point.
They can survive cold down to nearly absolute zero (the temp at which atoms stop moving).
They can withstand 1000x more radiation than any other animal.
It can survive a decade without water.
They were taken into orbit and left exposed to the anoxic vacuum of space, and not only survived, but reproduced.
They're harmless and very common. You've probably shared space with them without knowing it.
They can live in water well past the boiling point.
They can survive cold down to nearly absolute zero (the temp at which atoms stop moving).
They can withstand 1000x more radiation than any other animal.
It can survive a decade without water.
They were taken into orbit and left exposed to the anoxic vacuum of space, and not only survived, but reproduced.
They're harmless and very common. You've probably shared space with them without knowing it.
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Water bear is the common name for a diverse group of tiny animals - the tardigrades, indeed some species are candidates for the smallest animals of all. They are mainly herbivorous or feed on bacteria and do not present any real danger to humans, as far as I know, the are not pathogens either. This article gives good information about them.
http://en.wikipedia.org/wiki/Tardigrade
http://en.wikipedia.org/wiki/Tardigrade