Like us, dolphins are masters of their habitats. Both humans and dolphins have "adapted almost perfectly to the world we live in," former "Flipper" trainer Ric O'Barry writes. Dolphins aren't just sleek, strong swimmers -- they've got hefty brains (when compared to body size, dolphin brains place second after ours) and are capable of complex thought, as these studies show.
Dolphins are great at communicating
The distinctive whistles and clicks of a dolphin helps the marine mammal locate food in murky water -- and they can make these calls for a staggering 15 days. But research suggests there's much more going on with these sounds than echolocation -- bottlenose dolphins use vocal labels to identify each other and can remember other dolphins' whistles for decades.
[Listen to a whistling dolphin here.]
Dolphins are also adept at communicating with another species: humans. Researchers at the University of Honolulu's Dolphin Institute, for example, trained a dolphin named Akeakami to understand approximately 40 words of a rough sign language, including grammar. If a scientist said, "Left basket right ball," Akeakami knew to carry a ball from her right to a basket on the left.