Answer:
The jellyfish will move forward.
Explanation:
Newton's third law states that for every action there will be an equal and opposite reaction. As the jellyfish squeezes the side of their bodies, water is pushed out from the back of the jellyfish with a certain amount of force. According to Newton's third law, this action will move the jellyfish in the forward direction with the same force with which the water was squeezed backwards.