Wrong. It is said that the Dragon King has 9 sons. The youngest of all is from the daughter of the turtle Prime Minister and Dragon King. Thus the Dragon Turtle was born. If you talking about Xuan Wu (Genbu in japanese folklore), it belongs to the group of water gods. Borned with the head of a serpent and turtle body. Its cries brings forth tsunami and storms. It also represent Sadness. In some western folklores it was also to replace Leviathan as the Guardian of Water after Leviathan was banished into the water of Abyss due to it’s crime of Jealousy.