Just how smart are dolphins?

The intelligence of our dolphin friends continues to amaze us humans. From a neat article in the Guardian comes the below story:

At the Institute for Marine Mammal Studies in Mississippi, all of the dolphins are trained to hold onto any trash that falls into their pools until they see a trainer, when they can trade the trash for fish. In this way, the dolphins help to keep their pools clean.

A dolphin named “Kelly” has taken this one step further. When people drop paper into the water she hides it under a rock at the bottom of the pool. The next time a trainer passes, she goes down to the rock and tears off a piece of paper to give to the trainer. After a fish reward, she goes back down, tears off another piece of paper, gets another fish, and so on. This behavior shows that Kelly has a sense of the future and delays gratification. She has realized that a big piece of paper gets the same reward as a small piece and so delivers only small pieces to keep the extra food coming. She has trained the humans!

That’s not all Kelly has learned – one day she grabbed a sea gull that flew into her pool and waited to give it to the trainers, who in turn gave her lots of fish. This gave her an idea -- the next time she was fed, instead of eating the last fish, she took it to the bottom of the pool and hid it under the rock where she had been hiding the paper. When no trainers were present, she brought the fish to the surface and used it to lure the seagulls, which she would catch to get even more fish. She then taught her calf this stategy, who in turn taught other calves, and now baiting seagulls has become a pastime among the dolphins.

Amazing!