Sarasvata, or Sarasvan, is a male river god and sage. He is mentioned as a male river god in the Rig Veda. He is worshipped for peace, prosperity, protection, good spouse and offspring. The story of Sage Sarasvata as the son of Saraswati River is mentioned in the Shalya Parva of the Mahabharat.
Legend has it that Sage Dadichi was engaged in Tapas, or deep meditation, on the banks of Saraswati River. Indra, the king of Devas, was always insecure of Sages performing Tapas. He was worried that the intense mediation would threaten his powers. He feared that the Sage would replace him.
To alleviate his fears and to keep this throne safe, Indra deputed Alambusa, a celestial damsel, to seduce Sage Dadichi.
After several attempts, Alambusa succeeded in garnering the attention of the Sage. He was enamoured by her beauty and lost his self-control. He spilled his semen into Saraswati River.
As a result, Saraswati River became pregnant and in due course presented the Sage with a son who was named Sarasvata or Sarasvan.
It is said that later when there was severe drought all people abandoned the study of the Vedas. But Sarasvata continued the studies as he was nourished by Saraswati River with fishes. When the drought ended, people flocked to him for knowledge and he instructed the Vedas to them.
Those who acquired knowledge of Vedas from Saravata were the ancestors of present day Sarasvat Brahmin community.