Rigged -Animated along a curve, with NLA strips used
You can drive the ants speed with the parent of the armature, the walkcycle will adapt to speed of this object, and thanks to the curve deform applied after armature modifier, the ant can stick to any surface.
-2 NLA strips - one is the walkcycle, second is tentacle and head movement
This ant was used in production of an animated movie, it is simple, but functioning well. Thanks to DOF + motion blur can look realistic when not really big in the shot.