Newton's Third Law states that for every action, there is an equal and opposite reaction. This means that if one body exerts a force on a second body, the second body simultaneously exerts a force of equal magnitude and in the opposite direction on the first body. When the ant punches the finger, the finger exerts the same force on the ant. But because the ant has a much smaller mass compared to the finger, the ant's acceleration backwards is comparatively larger than the acceleration of the fin

Aawaz - Newton's third law.