The term for an animal's innate response to environmental stimuli is called a "reflex." Reflexes are automatic, rapid responses that occur without conscious thought, allowing animals to react quickly to potentially harmful situations. For example, if a hand touches a hot surface, the reflex is to pull it back immediately. This response is crucial for survival, as it reduces the chances of injury. Reflexes can be classified into two main categories: simple reflexes (such as the knee-jerk reaction) and complex reflexes, which may involve more coordinated actions. These instinctual behaviors play a vital role in an animal's interaction with its environment.