In Greek mythology, the Lernaean Hydra (Λερναῖα Ὕδρα / Lernaīa Hýdra) was an ancient and ruthless chthonic water monster in the form of a polycephalic serpent (whose number of heads ranges from three, five, seven or nine to a hundred, and even ten thousand depending on the source) and poisonous breath that Hercules killed in the second of his twelve labors.
The Hydra possessed the virtue of regenerating two heads for every one it lost or had amputated, and its lair was the lake of Lerna in the gulf of the Argolid (near Nauplia), although archaeologists have confirmed that this sacred place predates even the Mycenaean city of Argos, for Lerna was the site of the myth of the Danaids. Beneath its waters was an entrance to the Underworld that the Hydra guarded.
The Hydra was the daughter of Typhon and Echidna and in some traditions was the mother of Chimera. She was raised by Hera under a plane tree near the Amimone spring at Lerna. She was said to be the sister of the lion of Nemea and thus sought revenge for his death at the hands of Hercules. This is why she was said to have been chosen as a job for Hercules, so that Hercules would die.
The Hydra had many parallels in ancient Middle Eastern Religions. In particular, Sumerian, Babylonian and Assyrian mythology celebrated the deeds of war and the hunter-god Ninurta, whom the Angrim credited with slaying eleven monsters on an expedition into the mountains, including a seven-headed serpent (possibly identical to Mushmahhu) and Bashmu, whose constellation (despite having only one head) was later associated by the Greeks with the Hydra.
The constellation is also sometimes associated in Babylonian contexts with Marduk's dragon, the Mushhushshu.
After arriving at the swamp near Lake Lerna, Heracles and his nephew Yolaos began fishing for bass in the pool the reeds, they covered their mouths and noses with a cloth to protect themselves from the poisonous breath of the Hydra. Herakles shot flaming arrows into the monster's shelter (the fountain of Amimone) to force it out.
He then confronted it with his sword and began to cut off all nine of its heads. But every time one was cut off, another one was reborn in the same place stronger than the previous one. His nephew helped him by burning the neck of the severed head so that another would not be reborn.
In the end, the Hydra died headless and Heracles dipped the tips of his arrows in the blood of the Hydra so that they would be deadly to those he wounded (among them Nessus).
The details of the confrontation are explained by Apollodorus: Warning that he could not defeat the Hydra in this way, Herakles asked his nephew for help. The latter had the idea (possibly inspired by Athena) of using burning cloths to burn the stump of the neck after each decapitation, cauterizing the wound and thus preventing the two new heads from sprouting.
Heracles cut off all the heads and Yolaos burned the open necks, thus killing the Hydra. Herakles then took his one immortal head and buried it under a large rock on the sacred road between Lerna and Eleunte, dipping his arrows in the poisonous blood of the Hydra and thus completing his second work.
In an alternate version, Hera sent a crab to bite Heracles' feet and hinder him, hoping thus to provoke his death. However, Heracles crushed the crustacean and continued to fight the Hydra. Therefore, the queen of Olympus set the crab in the starry heavens as the constellation Cancer.
When Eurystheus, the king who assigned the labors to Herakles, learned that it had been his nephew who had given him the torch, he declared that he had not completed the work alone and therefore did not count toward the total of ten labors assigned to him. This mythical element is an ambiguous attempt to resolve the conflict between the ancient ten labors and the more recent twelve.
- The Spanish painter Francisco de Zurbarán painted ten canvases on the labors of Hercules, one of them being the death of the Hydra of Lerna at the hands of Hercules, which is in the Prado Museum.
- Romanesque capitals in the Church of Santa María de Bareyo (Cantabria)
- Film Jason and the Argonauts (1963), directed by Don Chaffey.
- Disney's Hercules movie (1997)
- Percy Jackson book: The Sea of Monsters
- Percy Jackson's Book: The Mark of Athena
- Percy Jackson Movie: Percy Jackson and the Lightning Thief
- Movie Hydra (2009)
- The video game God of War (2005)
- The video game Dark Souls (2011)
Mythographers tell that the Hydra of Lerna and the crab were put in the sky after Herakles killed them. Hera placed the crab in the Zodiac to follow the Lion, creating the constellation Cancer. When the sun is in the sign of Cancer, as the boreal summer and austral winter officially begin, the constellation Hydra has its heads nearby.
