At the Institute for Marine Mammal Research (Mississippi), scientists have taught dolphins to exchange any garbage in the pool for fish. This is how the animals helped to keep the pool clean. Dolphin Kelly began to use this system for her own purposes. Realizing that for any piece of paper, regardless of its size, she gets the same amount of fish, she began to hide the paper under the rock and tear off small pieces from it in exchange for fish.
Kelly didn’t stop there. One day she caught a seagull flying into the pool and got a lot of fish for it – the seagull was big. Then Kelly stopped immediately eating all the fish and began to make supplies with which she lured new seagulls. And then she taught the other dolphins this trick, and they all began to hunt seagulls too.