Adi Shesha or Ananta is the king of serpents in Hindu religion. The Mahabharata has an interesting story about Adishesha supporting the earth. He was born of Kadru, wife of Kashyapa Prajapati. Kashyapa had another wife named Vinita. One day the two wives quarreled over the color of the tail of Uchaishravas – a seven-headed flying horse of Indra, the king of devas or demigods, that was obtained during the churning of ocean or Samudra Manthan.
Kadru held that a part of the tail was black though knowing it
to be untrue. But in order to establish the truth of her statement, she asked
her serpent-children to cover the tail of white Uchaishravas so that it would
appear black.
Adi Shesha refused to do so and went on a long pilgrimage. At
the end of it, when he approached Brahma, the latter asked him to go to the
netherworld (Patala) and bear the earth. From that day, Adi Shesha started
supporting earth on his head.