Hydrostatic shock is a mechanical phenomenon caused by the incompressibility of a liquid and the velocity of the shockwave when a projectile strikes a fluid mass. Any fluid mass, whether it is an animal or an apple.
It is generally said that it occurs at about 2,000+ fps, but I have seen similar results when shooting jackrabbits with 125 g 357 Magnum ammo going about 1,580 fps.
When shooting animals, if the shock wave is larger than the animal shot, it will tear it to pieces. If the shock wave is contained within the animal's body, it will not.