This old constellation was already known to the ancient Greek. There are various legends entwined around this constellation. Dolphins were considered messengers of Poseidon, god of the sea in the ancient Greek myth and religion. Poseidon sent a Dolphin to find Amphritrite and persuade her of marrying him. They also saved the life of his son Arion, a kitharode and poet of his time, when he was attacked on his boat while traveling back home from Sicily in Italy.
This constellation does not belong to the zodiac.