The Hydra, in Greek mythology, was a huge serpent or dragon with nine heads that lived in the swamps near to the ancient city of Lerna.
The Hydra was a terrifying mythical monster that had the body of a serpent with nine vicious heads. If one head was cut off, two new ones grew in its place. This made the Hydra almost impossible to kill. One of the Hydra’s heads could never be harmed by any weapon. The breath of the hydra was so poisonous that it would kill any man who smelled it.
When it emerged from the swamp it would attack herds of cattle and local villagers, devouring them with its numerous heads. It terrorized the area for many years.
One of the twelve tasks of Hercules was to kill the Hydra. During the fight, Hercules kept chopping off the hydra’s heads but more and more new heads began to grow.
Hercules knew that if he continued like this, the Hydra would soon defeat him. So he asked his friend to burn the stump each time he cut off a head. This cauterized the wound and prevented any new heads from growing.
When all but one of the Hydra’s heads were chopped off, Hercules got a surprise. The Hydra’s last head was immortal and couldn’t be cut off. So Hercules buried the Hydra under a pile of boulders, and dipped his arrows into the monsters blood, making them poisonous.