1. As a symbol, the dolphin represents safety, swiftness, sea-power, a guide to the souls in the Underworld. A dolphin can also be a symbol of joy, playfulness, happiness, and, sometimes, of unconditional love.
In shamanic tradition, the dolphin represents the heavenly manna, the breath of life. "Dolphin is the keeper of the breath of life and teaches us how to release emotions. If Dolphin has appeared to you today, you are to be a link to some solution for the Children of the Earth. This can be a time when you are to link with Great Spirit and bring answers to your own questions or to those of others. In addition, this can be a time of communication with the rhythms of nature. You are put on notice to be mindful of your body rhythms, and the patterns of energy being fed to you from the Creator. Imitate Dolphin and ride the waves of laughter, spreading joy in the world. Breathe and experience the manna so freely given. Break existing barriers and connect to the Dreamtime or Great Star Nation. Know that we are all whole in the eyes of the Everliving One." (Jamie Sams and David Carson, Medicine Cards).
2. There are many "alternative" theories about the dolphins and whales. A lot of people believe that they may have extraterrestrial origins, more specifically, from the Sirius System.