Researchers around the world consider dolphins as the most intelligent animal on the Earth, second only to humans. Because of their brain power, scientists study dolphins to better understand how they think, to learn more about how dolphins communicate with each other and to find ways that allow humans to communicate with them.

In the Bahamas at the Roatán Institute for Marine Sciences, researchers have studied over 300 individual dolphins over the course of 30 years, which is about three generations' worth of bottlenose dolphins, the most common of sea-going dolphins noted for their distinctive personalities and intelligence.

Besides being able to learn tricks, dolphins at the institute also understand complex commands that require them to think. When given an "innovate" hand signal in tandem, two institute dolphins can perform a dozen or more behaviors that require them to be spontaneous and not repeat anything they've previously done in the session. Researchers posit the dolphins know what researchers want: to exhibit new and different behaviors.

The National Geographic article, "It's Time for a Conversation," reports that video and audio recorders track the dolphins at the institute chirping and squawking among themselves before executing the hand-signal command that requires the two dolphins to work together to perform something new. Like synchronized swimmers, the dolphins comply, and when asked to do more, dolphins Hector and Han go on to complete at least eight different synchronized behaviors which includes blowing large circular rings, pirouetting side-by-side, tail walking and rolling over together.

One dolphin, Kelly, at the Institute for Marine Studies in Mississippi developed quite a reputation for being smart, future thinking and delayed gratification, a sign of intelligence. Trainers and researchers at the institute typically reward dolphins for keeping their pools clean of paper litter by feeding them fish for every piece of paper they turn in.

Kelly, a very smart female, caught on quickly. She realized that it didn't matter how big the piece of paper was to get a fish. When she found a paper, she stashed it at the bottom of the pool beneath a rock. She would tear off only a little piece of the paper each time she wanted fish.

One day, she caught a gull that flew into the pool. She gave it to the trainers in exchange for a lot of fish, which gave her a brand-new idea. Instead of cleaning up the litter, she saved her last fish and stuck it under that same rock in the pool. She used that fish, when no trainers were around to catch her, to lure more gulls to the pool to turn them in for a lot more fish. Once she mastered this tactic, she taught the same thing to her calf and to other dolphins in the pool.

A lot of the research on dolphins is to determine whether they communicate with each other. Scientists at the University of St. Andrews in Scotland discovered that dolphins do seem to communicate with others and use signature whistles when meeting up with new pods in the wild. Called vocal labeling, these dolphins use repeated specific acoustic signals and whistles as a form of identification. Essentially, each dolphin has a "name." When the signature whistle is played back from a recording, the dolphin responds to its own identity signal, something humans do as well when called by their names.

In Hawaii, researchers kept a mother and her calf separated but connected by an underwater "telephone," to see if they would communicate with each other. After the mother and calf squawked, whistled and chirped at each other, researchers were convinced each dolphin not only knew who they were talking too, but enjoyed a lengthy conversation. Besides communicating, researchers think that they share information about hunting grounds, have specific labels or names for fish and seaweed, warn others of nearby sharks and call for backup when they need it.

Multiple studies show that dolphins communicate with each other in multiple ways: chirps, squawks, squeals and whistles. Dolphins also use high frequency band clicks and click bursts called echolocation. Individual clicks last between 50 to 128 microseconds with the highest frequencies rated at about 300 kHz.

The sonar bounces off the fish or object, creating a picture in the dolphin's brain. Dolphin sonar is so precise that it can tell the difference between the makeup of objects such as plastic, metal and wood at 100 feet. Other dolphins can "listen in" to this echolocation to figure out what they see. Other cetaceans like whales also use echolocation and this type of mammalian sonar to echolocate humans, other dolphin pods, food and predators.

Scientists posit that dolphin "languages" resemble human communication, and as such, seek ways to enable human-dolphin communication, like the work done at the Rockefeller University using an underwater, optical-driven touchscreen display. Researchers outfitted the dolphin habitats that house the display with audio and visual equipment to record how the dolphins interact with each other when accessing the new technology. This work is ongoing. The University hopes its work with dolphins will inspire "global policies for their protection."

Dr. Denise Herzing, a scientist who has also studied dolphins for decades, has mobile technology that records the names or signature whistles of dolphins and even creates signature whistles or names for human divers to allow interaction between the species. Both the humans and dolphins can request specific entities to speak and interact with. In a Ted Talk on the subject, she says, "imagine what it would be like to really understand the mind of another intelligent species on the planet."