No other animals are smart as people. But Some are very intelligent. Apes, monkeys, and dolphins are the smartest. They can learn to do many things. Some of them can even solve problems. For example, a dolphin in a tank was once playing catch with a feather. One time the feather stuck to the side of the tank, high above the water. The game seemed to be over. But the dolphin figured out how to get the feather back. It jumped up and brushed the feather loose with the side of its head. The dolphin had solved its problem, and the game could go on. Most animals are not nearly this smart. Animals such as clams, crabs, insects, and worms are the least intelligent of all. They can't learn to do very much. Some can't learn anything.