Adi Sesha

Mahabharata Adiparva astika parva section-36

Sri Sadgurubhyoh Namah

Sesha is the eldest son of Kadru. On hearing the curse of his mother, he was saddened. He embarked on a severe penance for Brahma, the grandsire of all. Brahmaji grants him a boon. Sesha says, "My brothers are wicked, they are always jealous of each other, I dont want to live among them. I want to make better use of my life for the benefit of the world". Brahmaji is pleased with the resolve and commands him to support the earth on his thousand heads. Sesha passes through a crevice in earth through to other end and supports it on his thousand heads. Brahmaji praises Sesha as dharma personification.

Probable meaning :

Earth or infact universe is supported on the basis of dharma. It is the dharma of clouds to rain, seed to sprout, sun to give energy etc.

Sesha is the supporter of earth. From piercing the earth to supporting it on his sahasra(thousand) heads, it is deeply symbolical of kundalini yoga.