Classical conditioning is very important to animal trainers, because it is difficult to supply an animal with one of the things it naturally likes (or dislikes) in time for it to be an important consequence of the behaviour. In other words, it’s hard to toss a fish to a dolphin while it’s in the middle of a jump or finding a piece of equipment on the ocean floor a hundred meters below. So trainers will associate something that’s easier to “deliver” with something the animal wants through classical conditioning. Some trainers call this a bridge (because it bridges the time between when the animal performs a desired behaviour and when it gets its reward). Marine mammal trainers use a whistle. Many other trainers use a clicker, a cricket-like box with a metal tongue that makes a click-click sound when you press it.