|The Lernaean Hydra was a serpentine water monster in Greek and Roman mythology. Its lair was the lake of Lerna. Lerna was reputed to be an entrance to the Underworld. In myth, the monster is killed by Hercules, using sword and fire, as the second of his twelve labors.|
According to Hesiod, the Hydra was the offspring of Typhon and Echidna. It possessed many heads. Later versions of the Hydra story add a regeneration feature to the monster: for every head chopped off, the Hydra would regrow new heads. The Hydra had poisonous breath and blood so virulent that even its scent was deadly.
He then confronted the Hydra, wielding either a harvesting sickle, a sword, or his famed club.
|Eurystheus sent Hercules to slay the Hydra, which Hera had raised just to slay Hercules. Upon reaching the swamp near Lake Lerna, where the Hydra dwelt, Hercules covered his mouth and nose with a cloth to protect himself from the poisonous fumes. He shot flaming arrows into the Hydra's lair, a deep cave from which it emerged to terrorize neighboring villages.|
|The weakness of the Hydra was that it was invulnerable only if it retained at least one head. Realizing that he could not defeat the Hydra, Heracles called on his nephew Iolaus for help. His nephew then came upon the idea of using a firebrand to scorch the neck stumps after each decapitation. Heracles cut off each head and Iolaus cauterized the open stumps. Seeing that Heracles was winning the struggle, Hera sent a giant crab to distract him. He crushed it under his foot. The Hydra's one immortal head was cut off with a golden sword given to Heracles by Athena.|