Training with the porpoise Freja at Fjord&Baelt. Her symbol is the green triangle
Some dolphinariums use different symbols when they train their dolphins. Each dolphin has its own symbol that it has learned to recognize. The symbols are mostly used to tell the dolphin which trainer it is supposed to be with during the training session. The trainer use to hold the symbol in the water and then the dolphin comes to its symbol and touches it with its nose. The dolphin is also often rewarded after that because it did the right thing.