““13. DOLPHINS These playful and friendly creatures are said to be next to humans for being the smartest animals on earth. Dolphins use complex language consisting of whistle sounds. They can also understand instructions and plan their actions well. FUN FACT: In one mammal study, a dolphin was given a fish as reward for every piece of trash it removes from the swimming pool. The intelligent creature thought of a way to get as much fish as it can. It took pieces of trash and ripped them into smaller parts! ””
