What animal lives deepest into the earth?

A nematode species known colloquially as a "devil worm" has been found living 2.2 miles below the earth's surface, making it the deepest-living animal known to man as of June, 2011. Prior to this discovery, it was thought that nematode species only lived within a few dozen feet of the earth's surface.

This "devil worm" is able to withstand enormous amounts of pressure and heat, both of which are factors that far under the earth's surface. They survive by living on tiny microbes, which were previously thought to be the only living things that could survive at such a depth.