Many people think that dolphins are the most intelligent of all animals, including pigs. Some people have suggested that a dolphin may be just as smart as an average two year old human child.
Dolphins are social animals, and enjoy the company of other dolphins. This means that most often they live in little communities called pods or schools. Sometimes, when there is alot of food available to the dolphins, they join up into even larger groups, called superpods. Sometimes a superpod may have more than 1000 dolphins in it.
Dolphins in a pod can develop a great friendship for one another. Sometimes they just chatter away using a variety of clicks and whistles. Sometimes, if a dolphin is injured, it's fellow dolphins will group around it, and care for it. In fact, dolphins have been known to even protect injured people who are under attack from sharks!
Dolphins don't just like to be social to other dolphins! Sometimes they will swim with larger animals such as whales, or they will come and play with humans. Sometimes they will follow ships when they sail across the ocean. In ancient Greece, seeing dolphins swimming along with a ship was considered a good omen.