If the startle response is strongly elicited through surprise then it will bring on the fight-or-flight response, which is a perceived harmful event, attack, or threat to survival that causes a release of adrenaline for a boost of energy as a means to escape or fight.
A strong startle response, caused by surprise, triggers the fight-or-flight response, which is interpreted as a dangerous situation requiring immediate action. This leads to the release of adrenaline to provide energy and enable either fleeing from danger or fighting back.