Vibration reception is widespread in arthropods. Many animals use vibrations to detect approaching predators or for communication to each other.  Some of my recent work also suggests that web spiders can use the intrinsic vibration properties of silk to identify if and where prey may be located on their web (Mortimer, Gordon, Holland, Siviour, Vollrath, Windmill 2014).  NPR covered this publication in morning edition, creating an animation to help describe the principles.

However even ground spiders use vibrations.  In fact, in some case vibration reception may be used to identify airborne sounds, such as if the animal is standing on a substrate that conducts vibration, like leaves. For example, in one study, wolf spiders on granite did not respond to sound while on paper they were responsive (Lohrey, Clark, Gordon, Uetz 2009). Wolf spiders will actively choose to be on leaves, which vibrate to rocks (Gordon and Uetz 2011).   In the same study we also found that when on hard, attenuating substrates, spiders use more visual signaling during courtship.

To sense vibrations, spiders have slit sensilla.  Below shows many slit sensilla arranged together in a lyriform organ on its leg.